The Enigma of Leibniz’s “Catholic” Writings of 1685

Abstract

The focus of this paper is a suite of Latin papers from 1685, some of which are still unpublished, in which Leibniz writes in the guise of a Catholic in order to defend Catholicism and counter Protestant objections, and this despite him being a lifelong Lutheran. After providing an overview of these writings (which I refer to as Leibniz’s “Catholic” writings) and the grounds for dating them to May–June 1685, I consider their purpose, arguing against the claim that they were intended to support Church reunion and suggesting instead that they were apologetic in nature, intended as a reactivation or reimagining of Leibniz’s earlier “Catholic Demonstrations” project. I identify the patron Leibniz had in mind for these writings as Landgrave Ernst von Hessen-Rheinfels and support this by a detailed comparison of the “Catholic” writings with the Leibniz-Landgrave correspondence and the Landgrave’s still-unpublished essays. This reveals that the Protestant arguments Leibniz uses in the “Catholic” writings are the very ones that he himself used when writing to the Landgrave, and that the responses Leibniz gives to these arguments are the very ones that the Landgrave used. I also consider the context of the writings, suggesting they were crafted during a period of personal uncertainty for Leibniz and possibly aimed at securing a position under the Landgrave.

1. Introduction

Little known to many scholars is a suite of Latin papers from 1685 in which Leibniz writes in the guise of a convinced Catholic with the aim of defending the reasonableness of the Catholic faith and rebutting Protestant arguments against joining the Catholic Church. These papers are henceforth referred to as his “Catholic” writings. That Leibniz would write such papers requires explanation, not least because he was himself a lifelong Lutheran who spurned every attempt to get him to convert to Catholicism. In light of Leibniz’s own religiosity, how are such writings to be explained? This is the central question of this paper, whose structure will be as follows:

In Section 2, I offer an overview of the “Catholic” writings published in the Academy edition of Leibniz’s work and present the grounds for dating the writings to February–October 1685, and then the grounds for narrowing this dating to May–June 1685. In Section 3, I consider a further writing missed by the Academy editors: a previously unpublished letter from the same timeframe as the “Catholic” writings, a letter in which Leibniz, in the guise of a Catholic, argues against the criticisms of an unnamed Protestant correspondent. I will argue that this text is a fictitious letter and that it should be treated as the first of the “Catholic” writings of 1685, with Leibniz quickly electing to abandon the fictitious letter format. In Section 4, I turn to the purpose of the “Catholic” writings and consider the case for viewing them as explorations for Church reunion, as some scholars have suggested. Against this, I will argue that the writings are more plausibly considered as apologetic in nature, as Leibniz himself presents them, and that they constitute a reimagining of his apologetic “Catholic Demonstrations” project, previously mooted when working for Catholic employers. In the case of the 1685 writings, I argue that the patron Leibniz had in mind was his Catholic correspondent Landgrave Ernst von Hessen-Rheinfels (1623–1693). This claim is secured by considering the “Catholic” writings alongside Leibniz’s correspondence with the Landgrave, which I do in Section 5. Here we will see that the arguments Leibniz attributes in the “Catholic” writings to Protestants reluctant to return to the Catholic Church are the very ones that he himself had used in his correspondence with the Landgrave when he felt the need to explain why he had not converted to Catholicism, while the responses to those arguments Leibniz gives in the “Catholic” writings are the ones that the Landgrave had used. In addition to such clear borrowings, I also show that in the “Catholic” writings Leibniz echoed a number of the Landgrave’s views. Lastly, in Section 6, I consider the circumstances of Leibniz’s life around the time of the “Catholic” writings and argue that these writings emerged during a time of great personal uncertainty about his position in Hannover and may have been intended to help him get a role or even a job under the Landgrave. In order to develop this account of Leibniz’s “Catholic” writings of 1685, I shall need to consider many still-unpublished texts, some by Leibniz, some by the Landgrave.

2. An Overview of Leibniz’s “Catholic” Writings of 1685

Let us start by listing the “Catholic” writings of 1685 as published in the Academy edition of Leibniz’s works:1

The Proper Starting Point of Our Faith

(LH 1, 7, 1 Bl. 3–4)

On the Unity of the Church

(A IV 7, 824–829)

Brief Preparatory Remarks in Relation to Apologetic Works

(A VI 4, 2298–2299)

Apology for the Catholic Faith Based on Right Reason

(A IV 3, 226–233)

Rationale of the Catholic Faith Against Sects of All Kinds

(A VI 4, 2302–2305)

Specimen of Catholic Demonstrations, or, Apology for the Faith Based on Reason

(A VI 4, 2323–2327)

Discussion about an Apology for Catholic Truths

(A VI 4, 2342–2345)

The Authority of the Church2

(A IV 3, 261–283)

On Attempting an Apology for Catholic Truth

(A VI 4, 2299–2301)

On the Catholic Church

(A VI 4, 2330–2332)

Thoughts about the Disagreement Between Protestants and Eastern Churches

(A IV 6, 714)

The One Catholic Church3

(A IV 3, 283–298)

On the Commandment of Love, Schism, and the Principles of the Church

(A IV 7, 830)

Apology for Catholic Truth

(A IV 6, 722–763)

On Schism, Catholic Faith, and the Catholic Church

(A IV 6, 716–719)

Rationale of the Catholic Faith4

(A VI 4, 2306–2323)

Although I include it here, “The Proper Starting Point of Our Faith” has actually not yet been published in full in the Academy edition, as it is treated there as an early draft of “Apology for the Catholic Faith Based on Right Reason” and so is presented piecemeal in the apparatus to that text (A IV 3, 226–228), requiring the reader to reconstruct it word-by-word. Aside from “The Proper Starting Point of Our Faith”, the remaining texts are unfortunately spread across no fewer than four separate volumes of the Academy edition, being found in one volume in the series of Leibniz’s philosophical writings (A VI 4), and in three volumes in the series of Leibniz’s political writings (A IV 3, A IV 6, and A IV 7), making it difficult to see the writings as forming a group and to appreciate the tight interconnections between them, of which there are many. Indeed, aside from overlapping themes and arguments, many of the writings borrow material from each other, sometimes verbatim, sometimes slightly modified, and this makes it possible to glean the probable sequence in which they were written, namely:

Figure 1. The sequence of the “Catholic” writings.

Figure 1. The sequence of the “Catholic” writings.

In Figure 1, the arrows indicate the borrowings of material. As is clear from the diagram, only one text (“Rationale of the Catholic Faith”) contains material that is neither borrowed from nor by another text.

Thematically, the “Catholic” writings seek to defend the reasonableness of the Catholic faith by rebutting both philosophical critics of Catholic dogmas and Protestant arguments against joining the Catholic Church.5 Some writings demonstrate both aims, others only one. In several of the writings, Leibniz writes in the guise of a Catholic, while in others the Catholic guise is implied. Since these writings have attracted little attention among scholars to date, it is worthwhile giving an overview of the contents of the principal ones.

“The Proper Starting Point of Our Faith” concerns the use of reason in religious matters. In this text, Leibniz argues that as scripture avoids philosophical questions, it may sometimes need to be interpreted in light of firm conclusions reached by reason, such that where a literal reading of certain passages of scripture conflicts with something established by reason, those passages should be interpreted in a non-literal way. He gives as an example the Copernican hypothesis, arguing that passages that appear to conflict with this (such as Joshua 10.12–13) should be interpreted figuratively, to ensure that those convinced of the heliocentric theory are not deterred from being part of the Church. Leibniz ends on a note of reassurance:

In fact, an English or Dutch astronomer who professed Copernicus today need not fear any opposition from Catholics, nor will the Church condemn anyone who perhaps thinks that the more probable opinion, which is self-evident, has the greatest appearance of truth in it; and hence no danger to the Catholic faith can arise in this light of our age since the fear of offence seems to have long since ceased.

(LH 1, 7, 1 Bl. 4v)

In a similar vein, in “Apology for the Catholic Faith Based on Right Reason”, Leibniz presents himself as someone who, despite having always thought that one should listen to authority more than reason, now seeks to defend the Catholic faith using reason. However, he does this only by providing a string of quotations from Augustine, with the aim of showing that, in Augustine’s opinion, the aim of scripture is to teach the truths necessary for salvation, not those of physics or cosmology. A broader approach to defending the faith using reason is taken in “Specimen of Catholic Demonstrations, or, Apology for the Faith Based on Reason”. Insisting that there is a consensus between religion and true philosophy, Leibniz laments that many people of his time abuse reason to reject incorporeal substances and providence, and to attack the doctrines of the Trinity, Incarnation, and other mysteries as impossible. Heeding the call of the fifth Lateran Council to defend the faith using reason, Leibniz then outlines some doctrines (recognizably those of Descartes and Spinoza), which he sees as poisoning minds against religion, before offering a brief sketch of some tenets of his own philosophy to serve as antidote.

The guiding concern of “On the Unity of the Church” is what is required to enable Protestants to join the Catholic Church now that doubts about doctrinal continuity are over: “it has been very clearly shown that nearly all of those things censured in the dogmas of today’s Church were already received at the time of Saint Augustine, and this is shown partly by clear testimonies, partly by not despising the argument of the perpetuity of the faith” (A IV 7, 824). Leibniz diagnoses two problems: the abuses of the Catholic Church (which are not specified but probably refer to the selling of indulgences and the worship or adoration of saints, images, and relics) and “some personal arguments drawn either from the new philosophy or elsewhere”, which give rise to the concern that the Church “demands not only that they [Protestants] do not condemn but also that they approve and believe things which, speaking from their hearts, seem manifestly either false or uncertain” (A IV 7, 825). To the first problem, Leibniz insists that Protestants should focus on the Church’s teachings rather than the improper practice of some of its members, and to the second, he maintains that the Church will welcome Protestants who do not approve some articles of faith, so long as they are not obstinate in their views, even advising Protestants to keep silent about their doubts when joining the Catholic Church if they are concerned about causing offense or getting themselves excluded.

In “The Authority of the Church”, Leibniz records the complaints of “moderate” Protestants: that the Catholic Church demands not only that they believe things (not specified) they are convinced are not true, but also that they condemn those with different views (again, not specified), his diagnosis being that such complaints stem from conflating the errant opinions and practices of some individual Catholics with the approved opinions and practices of the Church. Leibniz then identifies the aim of the piece, to advance general arguments and examine individual controversies to make it evident that Catholic dogmas are not absurd and inconsistent with reason, as some Protestants claim. After setting out this aim, which he makes no attempt to meet, Leibniz makes a case for the importance of being guided by reason even in theological matters, before turning to an extended discussion of Bible criticism, focusing in particular on the canonicity of certain books, textual variations in the New Testament, the authenticity of some of the epistles of the New Testament, and the correct interpretation of certain passages, stressing that only the authority of the Church can resolve such problems, not human authority, as Protestants claim. On a different tack, “The One Catholic Church” begins with Leibniz bemoaning the lack of love in those who have separated themselves from the Church and insisting that Protestant principles are inferior to Catholic ones. He considers Protestant complaints about abuses in the Church and the perceived requirement by the Church that Protestants believe things that are not true, responding that abuses should be attributed to the individuals who commit them rather than the Church itself, and that on matters not pertaining to salvation the Church “does not demand unanimity” (A IV 3, 297).

The target of “Discussion about an Apology for Catholic Truth” is those who “hate the teaching of the Roman Church ... because they imagine that a severe servitude is imposed on the minds of Catholics, and that books and letters are oppressed by the most vigorous inquisition, so that it is necessary for wise people to become hypocrites in front of others, while the rest, blinded by prejudices, live in a kind of barbarism” (A VI 4, 2343). Although the stated aim of the text is to defend Catholic dogmas against such charges, Leibniz instead opts to tackle the “worst opinions” (A VI 4, 2344), which he identifies as those of Spinoza, leading to a brief outline of some of Spinoza’s views along with Leibniz’s rebuttals. Before taking this philosophical turn, Leibniz touched upon the idea of writing an “Apology for Catholic Truth”, an idea he picks up again in “On Attempting an Apology for Catholic Truth”, which is clearly intended to be a preface or introduction to such a work. Leibniz explains that the aim of the “Apology” is to show that the Church’s doctrines are safe, reasonable, and do not conflict with history, true philosophy, or tradition, though in this text he gives no indication as to how he would show such things.

In addition to this prefatory piece, Leibniz also drafted “Apology for Catholic Truth”, which is by far the longest and most detailed of the “Catholic” writings. This text covers many topics familiar from previous ones, such as the concern that the Church imposes servitude on the minds of Catholics, Protestant complaints about Roman Catholic dogmas and practices, and the superiority of Roman Catholic principles to those of Protestants. However, “Apology for Catholic Truth” also contains much that is new, most notably a lengthy defense of the adoration of the Eucharist against objections made more than fifty years earlier by the Calvinist minister Jean Daillé (1594–1670). The text ends with a discussion of the use and misuse of reason in religious matters, with Leibniz briefly outlining and responding to various doctrines of Hobbes and Spinoza. In response to Hobbes’ claim that whatever exists is corporeal, Leibniz gives the very first statement of his so-called “mill argument” for the immateriality of perception and the mind, an argument he would later use with some frequency against materialist understandings of the mind and its operations:

Imagine a machine of any kind: what will you have besides something like a clock or a mill of some kind, however variable? From this, of course, no perception will ever arise, and since motion is homogenous to motion, shape to shape, and extension to extension, it will be readily apparent that one is no more suited than another to producing sense, no matter how they may be combined with each other in various ways. But if they establish something besides size, shape, and motion in body, they thereby introduce something incorporeal, for we understand as incorporeal that which does not arise from these.

(A IV 6, 761)

Written from the perspective of a Catholic who has engaged (successfully) with those who attack Catholic dogmas, “Rationale of the Catholic Faith Against Sects of All Kinds” is intended as an introduction or preface to an already-written longer work entitled “Rationale of the Catholic Faith”, in which Catholic dogmas are shown not to be absurd. As it happens, Leibniz produced two drafts of a text entitled “Rationale of the Catholic Faith”, the first of which bears the subtitle “in which it is shown, in a brief specimen, that Catholic dogmas are more agreeable to reason than those of any other sect”, though both drafts have a much narrower aim than defending distinctly Catholic dogmas, instead being largely concerned to outline Leibniz’s conception of God (as a being that exists, is eternal, unique, incorporeal, a mind, and omniscient, omnipotent, good, and just), which he concedes is orthodox not just among Catholics but also among Protestants, and defend it against heterodox ideas advanced by the Socinians and Remonstrants.

Although in several of the texts Leibniz refers or alludes to his intention to publish a little book, none of the “Catholic” writings can be considered polished or even, in some cases, finished. Indeed, some end abruptly mid-sentence, such as “Apology for Catholic Truth” and “Rationale of the Catholic Faith Against Sects of All Kinds”, while others do not contain treatments of topics that Leibniz promises to cover in them, such as “The Authority of the Church”, which ends before Leibniz has completed his plan of citing passages from St. Augustine about the importance of reason in theological matters, tackling the controversies, and ending with a discussion of Church anathemas. Nevertheless, as a group, the “Catholic” writings would easily make a small book of approximately 70,000 words in English translation, albeit with some overlaps, since, as noted, many of the writings share verbatim or near verbatim certain phrases, sentences, or even paragraphs.

As for when they were written, there are good grounds to think that the “Catholic” writings were all written between February and October 1685. While several of the manuscripts bear no watermark, and one (“The Authority of the Church”) bears a watermark so uncommon that it cannot be used for dating purposes, others bear one of three watermarks (nos. 1777, 1794, and 1816 in the watermark catalog of the Gottfried Wilhelm Leibniz Bibliothek) that are securely attested to February–October 1685, while the others without watermarks are so connected (both thematically and in terms of content) to those with watermarks that they must have been written in the same timeframe. It is unlikely that the “Catholic” writings were written across the whole of this period, however; it is more probable, given the tight interconnections between them, that they were all written within a relatively short timeframe of a matter of weeks or, at most, a couple of months. And indeed, it is possible to identify the months and thus narrow the dating, as external evidence suggests that Leibniz was working on the “Catholic” writings across May and June 1685. In a letter written at the end of May 1685 to Veit Ludwig von Seckendorff (1626–1692), Leibniz states that “neither war nor pestilence nor famine has harmed Europe as much as the dissensions of religion” (A I 4, 508), recalling similar remarks made near verbatim in “The One Catholic Church” (A IV 3, 286), “On Schism, Faith, and the Catholic Church” (A IV 6, 716–717), “Discussion about an Apology of Catholic Truth” (A VI 4, 2343), and “Apology for Catholic Truth” (A IV 6, 722). And in exchanges with Gerhard Wolter Molanus (1633–1722), probably from June 1685, about which works of Jean Daillé were available to him, Leibniz reports that Daillé’s Apologie des Eglises reformées [Apology for Reformed Churches] was one of the books in the ducal library in Hannover of which he was in charge (A I 4, 514). This was the very book from which he expounded and critiqued the key claims in his “Apology for Catholic Truth” (A IV 6, 749–754) and cited a lengthy passage in “On Schism, Catholic Faith, and the Catholic Church” (A IV 6, 717–718). The exchanges with Molanus indicate that he was studying Daillé’s writings in June 1685, with the only other evidence of his study of them to be found in the two aforementioned texts. Therefore, on the basis of the external evidence provided by the letters to von Seckendorff and Molanus, it is reasonable to suppose that Leibniz was working on his “Catholic” writings during May and June 1685 (and perhaps a little earlier or later than this, though there is no evidence for this). We shall explore the possible significance of this dating in Section 6. Now, however, we need to consider a further text that has clear connections to the “Catholic” writings detailed above, and indeed, as I shall argue, is probably the first of them.

3. The Letter to an Unnamed Protestant Correspondent

The text in question is a draft letter in Leibniz’s hand; it has yet to appear in the Academy edition and has not been published elsewhere. The draft letter is ostensibly a reply to a no-longer extant letter received from an unnamed Protestant correspondent who had given three reasons for not joining the Catholic Church. Leibniz summarizes these reasons at the start of his reply: (1) that Protestant theologians do not accept that Roman Catholic dogmas do not overturn the foundation of salvation; (2) that even if Catholic dogmas are consistent with the foundation of salvation or are tolerable, they are not true; indeed some, such as the dogma of transubstantiation, are absurd and impossible; (3) “that the Roman Church imposes servitude on minds, does not want to allow common folk to read Holy Scripture, seizes books and letters with intolerable inquisition, and forces everyone to follow its decrees even in matters not pertaining to salvation.” As a result of this,

people either become hypocrites by speaking against their conscience, or are blinded by prejudices, not daring to open their eyes to the light of truth. Hence, [you claim that] all true philosophers hate the Roman tyranny (as you like to call it) as contrary to the progress of the sciences and the good of humankind.

(LH 1, 12, 2 Bl. 144r)

As an example, the unnamed Protestant correspondent had put forward the Copernican hypothesis,

which now almost all excellent astronomers hold, or would willingly hold if it were within their discretion; and indeed, [you say that] those who live among Protestants freely profess this opinion, while Catholics are terrified by the example of Galileo, who suffered severe persecution for asserting the truth. Hence you conclude that an English or Dutch astronomer or a Cartesian philosopher from those nations will never sincerely become a Roman Catholic if they have to renounce the doctrines they consider most certain.

(LH 1, 12, 2 Bl. 144r)

Before we proceed, it is worth noting the clear connection between this letter and other of Leibniz’s “Catholic” writings. For one thing, the paper bears the same watermark (no. 1816 in the watermark catalog of the Gottfried Wilhelm Leibniz Bibliothek) as several of those writings, putting it within the same timeframe. Secondly, Leibniz reused the complaint about the Catholic Church imposing servitude on minds in “The Authority of the Church” (A IV 3, 265), “Discussion about an Apology for Catholic Truth” (A VI 4, 2342–2343), “On Attempting an Apology for Catholic Truth” (A VI 4, 2301), and “Apology for Catholic Truth” (A IV 6, 724), where he writes of Protestants:

Therefore, they complain that Rome engages in tyranny over minds and imposes servitude on intellects, while she orders everyone to believe whatever she has pleased herself to lay down as an undoubted article of faith, and pronounces anathema on dissenters who cannot act contrary to their own conscience... This is why some people, by a ridiculous but most unfortunate error, persuade themselves that the more intelligent among Catholics must become hypocrites, while the rest must pluck out the eyes of mind lest they see the light of truth.

Lastly, the unnamed Protestant correspondent’s example of the Copernican hypothesis was reused in “The Proper Starting Point of Our Faith”, with Leibniz even there referring to “an English or Dutch astronomer” (I refer the reader to the quotation in Section 2), as the unnamed correspondent had done. Indeed, the letter to the unnamed Protestant correspondent was probably written just before “The Proper Starting Point of our Faith” and was a key source for that and subsequent texts.

Returning, then, to the contents of Leibniz’s letter; having outlined the correspondent’s reasons for not joining the Catholic Church, Leibniz then addresses them one by one. Moreover, Leibniz responds in the guise of a Catholic, referring to Catholic dogmas as “our dogmas”. However, his responses have little substance and certainly offer little to win round a recalcitrant Protestant. To the reluctance of Protestants to concede that Catholic dogmas do not overturn the foundation of salvation, Leibniz simply expresses his wish that the unnamed Protestant correspondent had identified the offending dogmas, and then states:

I do not think you would still call the worship of saints or images idolatrous, nor would you assert that we trust in our own merit instead of Christ’s; you even acknowledge that we assert that in the sacrament of the Eucharist we adore not the bread, or its species, or the subject of the species, but God alone.

(LH 1, 12, 2 Bl. 144v)

Leibniz’s response to the second objection is equally uncompelling. On the matter of whether the Church’s doctrines are true, Leibniz insists that “one should believe the Church more than a private judgement” but should anyone think they have strong reasons for thinking otherwise, “they can seek a solution from the learned”, by which he presumably meant: learned Catholics. Leibniz continues: if all else fails, and “one cannot compel the intellect, one can still adhere to the faith of the Church with their will” (LH 1, 12, 2 Bl. 144v). It is worth noting in passing that this claim surely does not represent Leibniz’s own view. For example, in a letter to his Catholic correspondent Landgrave Ernst von Hessen Rheinfels of 7 April 1684, Leibniz insisted that a Protestant who held views divergent from those of the Catholic Church “cannot be of the Roman Church … unless he speaks against his conscience, since he cannot change his opinions at will” (LBrF 20 Bl. 2v), and in a letter from 4/14 March 1685, he informed the Landgrave that it is not in our power to change opinions we have reached on good reasons (A I 4, 355). Therefore, contrary to what he suggested to the unnamed Protestant correspondent, Leibniz did not believe that the will could operate independently of the intellect. Returning to the letter to the unnamed Protestant correspondent, Leibniz concludes his response to the second objection with the statement: “As for transubstantiation, it is certain that many distinguished philosophers sincerely hold it and fully profess that they can adequately address all objections” (LH 1, 12, 2 Bl. 144v). As responses go to concerns about the coherence of transubstantiation, this one is especially insubstantial, so to speak.

To the third objection, that the Church imposes servitude on minds, Leibniz offers the following response:

It is false that the Church defines anything distinctly in matters not pertaining to salvation. It has not condemned the opinion about the motion of the earth, but its rulers initially prohibited its teaching only to avoid scandal, and because at that time it seemed to many eminent people that it was contrary to holy scripture. Now, however, even prominent theologians declare that, when the doctrine is taught, no scandal should be feared from it, [and] it can be held without issue. If any astronomer from those you mention wanted to become Catholic while holding on to this opinion, no one would cause them trouble because of that.

(LH 1, 12, 2 Bl. 144v)

As we saw in Section 2, Leibniz made the same response in “The Proper Starting Point of Our Faith” and “On the Unity of the Church”. We shall see in Section 5 Leibniz’s source for this particular response.

While more might be said about the quality of Leibniz’s responses to the unnamed Protestant correspondent, it is the very existence of such a letter that raises the most pressing questions. Who was Leibniz writing to? How did Leibniz manage to get himself in a position where his correspondent believed he was writing to a Roman Catholic? Who else was involved in facilitating the deception? Did Leibniz send his letter? When and why did the correspondence end? How many more items in the correspondence were there? Unfortunately, there is no way to answer any of these questions, as the only extant item in the correspondence is Leibniz’s draft letter, which does not answer any of the questions it raises. As Leibniz’s Nachlaß is silent about the correspondent and the circumstances surrounding the correspondence, we should wonder whether we are asking the right questions. Indeed, we should be open to the possibility that there never was an unnamed Protestant correspondent and that the letter is fictitious, not in the sense that Leibniz did not write or author it (evidently he did, his handwriting is unmistakable, and the various deleted passages indicate that he took some care to get the letter how he wanted it), but that it was written to look like an item in an exchange between a Protestant and Catholic when there was no exchange and no recipient. This would certainly explain why the letter to which Leibniz supposedly responds is not extant in his Nachlaß and why there is no trace in his Nachlaß of any other items in the correspondence beyond the one draft letter nor any trace of how such a deceptive correspondence was set up and facilitated. Moreover, by 1685, Leibniz had a track record in composing fictitious letters. For example, in 1677 he composed two fictitious letters ostensibly to the same unidentified “friend”, both on theological matters (see A VI 4, 2189–2196 and 2197–2202), while in 1681 he composed a letter ostensibly from the Italian astronomer Giovanni Domenico Cassini (1625–1712) in which he (Leibniz, or pseudo-Cassini) reported some of Leibniz’s quadrature results, the plan being to publish it under Cassini’s name (LH 35, 15, 5 Bl. 6; for analysis and discussion, see Strickland 2023). It is not implausible, then, that the draft letter to the unnamed Protestant correspondent is another of Leibniz’s fictitious writings, in which he used the form of a fictitious letter to circulate ideas without attaching his name thereto. One finds the use of fictions in some of the other “Catholic” writings also. In “Rationale of the Catholic Faith Against Sects of All Kinds” (A VI 4, 2305), “Specimen of Catholic Demonstrations” (A VI 4, 2325), and “Apology for Catholic Truth” (A IV 6, 755), Leibniz claimed that on his travels and at court he had met many people who were intelligent but corrupted by the new philosophy, namely, that of Descartes and Spinoza, and that he had engaged these people in debate in order to show that Catholic doctrines were in harmony with true philosophy. In “Discussion about an Apology for Catholic Truth”, Leibniz developed this trope into a fictitious account of his encounters with freethinkers during a journey to Holland, in which he “demonstrated at length that Catholic doctrine is wonderfully in harmony with true philosophy and Catholic teaching with prudence” (A VI 4, 2343). And indeed, one might treat all his “Catholic” writings as fictitious inasmuch as they were designed to mislead the unsuspecting reader into thinking the author was Catholic rather than Lutheran, a deception that would have been maintained by Leibniz’s stated intention in “On Attempting an Apology for Catholic Truth” to publish the work anonymously (A VI 4, 2300). Bearing all of that in mind, it is not unreasonable to suppose that the draft letter to the unnamed Protestant correspondent is fictitious. Moreover, since the draft letter contains early formulations of ideas and arguments that would reappear, often in expanded or more polished form, in some of the other “Catholic” writings, as we have seen, it is probable that the draft letter was not so much the prelude to or catalyst for the “Catholic” writings but the very first of them, Leibniz initially experimenting with the fictitious letter format before abandoning it in favor of writing more traditional essays.

4. The Purpose of Leibniz’s “Catholic” Writings

Now that we have sketched some of the key ideas in Leibniz’s “Catholic” writings, we need to consider what they were for. As already noted, these writings have attracted little interest among contemporary scholars; the few who do discuss them describe them simply—and without further analysis—as attempts “to explore the possibility of reuniting Catholics and Protestants from the perspective of an irenically-minded Catholic” (Waldhoff 2015, p. 618; cf. 622) or as “sketches exploring the possibility of church reunification” (Antognazza 2018, p. 761). The Academy editors likewise present the various “Catholic” writings as contributions to his longstanding aim to bring about “reunion of the Christian denominations” (A IV 3, XVII). Such a suggestion has some superficial plausibility, but this is weakened upon scrutiny, as we shall see.

By 1685, there was a concerted attempt at uniting Catholics and Lutherans led on the Catholic side by Cristobal de Rojas y Spinola (c. 1626–1695), Bishop of Tina (later of Wiener-Neustadt), and on the Lutheran side by Gerhard Wolter Molanus (1633–1722), the abbot of Loccum, both of whom were known personally to Leibniz and were among his correspondents. The essence of the proposal that emerged from their negotiations in 1683 was for a preliminary reunion of the Lutheran and Catholic Churches, with doctrinal disagreements between the two sides to be settled at a future ecumenical council at which Lutherans would be properly represented (see Spinola’s “Regulae circa christianorum omnium Reunionem” of 1683, LH 1, 13 Bl. 135v–136v). Although Leibniz was not party to these negotiations, he was aware that they were happening, and by April 1683 he was aware of the proposal drawn up by Spinola (see A I 3, 568). He would also have been aware of the fierce criticisms that the proposal attracted from all sides, including a stinging attack from Pierre Bayle in his newly launched periodical Nouvelles de la republique des lettres (Bayle 1684), a copy of which is in Leibniz’s papers (see LH 1, 13 Bl. 338). Curiously, Leibniz’s “Catholic” writings do not mention the reunion negotiations per se, but several of them do make mention of “a remarkable document” (A IV 3, 263 and 296) or “an important document” (A IV 6, 725) prepared by the Protestant negotiators, in which it is noted that Protestant Churches following the principles of the Lutheran theologian Georg Calixt (1586–1656) “recognize that the foundation of salvation among Roman Catholics is sound”. Leibniz mentions this only to show that when Protestants are not driven by passions or an enthusiasm for controversy, they are capable of acknowledging that Catholic dogmas do not threaten salvation. He does not indicate that the document stemmed from reunion negotiations, about which he is silent.

It would be a stretch to see Leibniz’s “Catholic” writings as contributions to the reunion efforts spearheaded by Spinola and Molanus, as the focus of Leibniz’s writings differs markedly from anything in Spinola’s reunion proposal. This raises the question: if the “Catholic” writings were not intended as a contribution to that Church reunion effort, to what reunion effort could they have contributed? The only answer could be a sui generis reunion effort, independently devised by Leibniz and not sanctioned by anyone with the authority to do so. Accordingly, to see the “Catholic” writings as a contribution to Church reunion is to see Leibniz as a maverick operator, pursuing his own reunion strategy independently of the one negotiated by senior Catholics and Lutherans who could, unlike Leibniz, plausibly claim to speak for their respective Churches (even if opponents sometimes denied this). Moreover, it would have to be a negative sui generis reunion effort, designed to clear away some of the hurdles that some Protestants had to joining the Catholic Church, rather than a positive sui generis project that laid out a roadmap or proposal as to how reunion between entire Churches might be effected. This is because Leibniz’s “Catholic” writings are addressed to those individual Protestants who have a very specific set of concerns that prevent them from joining the Catholic Church, or to those who have separated themselves from the Church on the basis of being led astray by heterodox philosophies. In this, Leibniz’s “Catholic” writings are very narrow and idiosyncratic, as they do not attempt to address Protestant opposition to the office of the Pope, for example, or to assuage Protestants deterred by the Catholic doctrine of purgatory, or by the tone or content of the decrees of the Council of Trent, or by the Catholic reliance on tradition rather than just scripture alone; in fact, the “Catholic” writings do not even mention such issues, despite their being commonly identified at the time as huge stumbling blocks to Church reunion. Leibniz’s “Catholic” writings, then, were not a credible platform for Church reunion. However, with that said, it is doubtful that they were intended to be.

Rather than see Leibniz’s “Catholic” writings as constituting such a negative sui generis Church reunion effort, which would make them look quite shallow and incompetent, I suggest that they are better understood in light of his longstanding “Catholic Demonstrations” project, first conceived in the late 1660s while he was working under the Catholic convert Baron Christian von Boineburg (1622–1672) at the court of Mainz. The “Catholic Demonstrations” was intended as a systematic apology for the Christian faith as understood within a Catholic framework. In his original plan (from 1668–1669) for what would have been a book of considerable size, Leibniz indicated that the prolegomena would deal with the elements of philosophy (metaphysics, logic, mathematics, physics, and practical philosophy), part 1 with demonstrations of God’s existence, part 2 with demonstrations of the soul’s immortality, part 3 with demonstrations of the possibilities of the Christian mysteries, and part 4 with demonstrations of the authority of the Catholic Church and of the authority of scripture (see A VI 1, 494–500/Leibniz 2016, pp. 21–35). Of the 76 chapters mooted for the work, Leibniz managed to sketch only a handful of specimen essays before the project fell by the wayside (for some of the essays, see A VI 1, 508–513/Leibniz 2016, pp. 35–42, and A VI 1, 515–517/Leibniz 2016, pp. 42–46). Late in 1679, Leibniz attempted to revive the project, outlining it in a series of letters to his then-employer, the Catholic convert Duke Johann Friedrich of Hannover (1625–1679) (see A I 2, 224–229), to whom he described it as a work of three parts:

the first would contain demonstrations about God and the soul, since indeed I have some startling ones. The second would contain proofs of the Christian religion, and of the possibility of our principal mysteries, particularly of the Trinity, the Incarnation, the Eucharist, and the resurrection of bodies. The third part is about the Church and its authority, about the divine right of the Church hierarchy, and about the limits of secular and ecclesiastical power.

(A I 2, 225/Leibniz 2016, p. 48)

The duke died on 18 December 1679, without ever having seen Leibniz’s letters on the “Catholic Demonstrations” project, leading Leibniz to shelve the proposal for a second time (for further details of the project, see Dingel 2019).

It is worth noting that although the “Catholic Demonstrations” is sometimes described as a Church reunion project, Leibniz himself made no such claims for it. Indeed, in structure and content, the “Catholic Demonstrations” is much closer to apologetic works that begin with a “preamble to the faith”, in line with the long tradition which held that belief in God’s existence is a precondition or “preamble” to faith rather than an article of faith in its own right (see, for example, Diroys 1683; Abbadie 1684). According to this tradition, belief in God’s existence is logically prior to belief in his revelation (after all, the thinking goes, one must first have faith that there is a God before one can have faith in his Word), and since God’s existence was demonstrable by the natural light of reason while the content of his revelation was not, a program of apologetics had to begin by establishing the former before moving on to consideration of the latter (see Kors 1990, pp. 110–31).

Now, from the outline given in Section 2 it should be clear that many of the “Catholic” writings take up some of the topics of the “Catholic Demonstrations” project as Leibniz conceived it in both 1668–1669 and 1679, though none is anything like as systematic as Leibniz originally intended the “Catholic Demonstrations” project to be; some of the “Catholic” writings address the existence of God (for example, “Rationale of the Catholic Faith”), some address the authority of the Church (for example, “The Authority of the Church” and “Apology for Catholic Truth”), but none attempts to cover all of the topics mentioned in one or other of the plans for the “Catholic Demonstrations”. Nevertheless, the clear thematic links and the fact that Leibniz used “Catholic Demonstrations” in the title of one of the “Catholic” writings (“Specimen of Catholic Demonstrations, or, Apology for the Faith Based on Reason”) do suggest a connection between the “Catholic Demonstrations” project and the 1685 “Catholic” writings, even if only a loose or imperfect one. This might explain Leibniz’s willingness to concoct and consider different titles for the little book that his “Catholic” writings were intended to yield (namely, “Apology for the Catholic Faith”, “Apology for Catholic Truth”, and “Rationale of the Catholic Faith”), the alternative titles perhaps reflecting Leibniz’s realization that what he was working towards with his “Catholic” writings was different enough from the “Catholic Demonstration” project that it warranted a different name, though this is speculation.

Nevertheless, the “Catholic” writings do look to be the same kind of work as the “Catholic Demonstrations”, as between them they offer a preamble to the faith along with an apology for Catholicism. Indeed, several of the “Catholic” writings (such as “Specimen of Catholic Demonstrations, or, Apology for the Faith Based on Reason”, “Rationale of the Catholic Faith Against Sects of All Kinds”, “Discussion about an Apology for Catholic Truth”, and parts of “Apology for Catholic Truth”) are primarily concerned with addressing atheistic or heterodox currents of thought, especially as found in Hobbes, Descartes, and Spinoza. These writings might best be thought of as “preambles to the faith”, while the other “Catholic” writings have much more the style, tone, and content of traditional apologetic writings than those seeking to offer a platform for Church reunion. Moreover, this corresponds with how Leibniz himself saw them, with him often using “apology” in the title and describing his project not as promoting peace, reconciliation, or union but as “the defence of our faith” (A IV 6, 758). For all these reasons, then, I suggest the “Catholic” writings represent the reactivation, or rather the 1685 reimagining, of the “Catholic Demonstrations” project that was first conceived when Leibniz worked in Mainz.

Now, since both the original plan for the “Catholic Demonstrations” and the plan for the proposed 1679 version were conceived as being sponsored or supported by prominent Catholic nobles, namely, Baron Christian von Boineburg and Duke Johann Friedrich, respectively, who did Leibniz have in mind as sponsor or patron of the 1685 incarnation? The most likely candidate, in fact probably the only one, is Landgrave Ernst von Hessen-Rheinfels, as in 1685 Leibniz could not count any other Catholic nobles among his correspondents or acquaintances. As we look more deeply into the content of Leibniz’s “Catholic” writings, by placing them side-by-side with his correspondence with the Landgrave, we shall see that there is solid evidence for thinking that he did indeed have the Landgrave in mind as a patron, if not a collaborator. It is to this that we now turn.

5. Leibniz’s “Catholic” Writings and the Leibniz-Landgrave Correspondence

When Leibniz’s “Catholic” writings are read alongside his correspondence with the Landgrave, one thing that leaps out straightaway is that the reasons Leibniz puts in the mouth of Protestants reluctant to join the Catholic Church are the very reasons he himself identified to the Landgrave as the ones that prevented him from joining the Catholic Church. Recall from Section 2 that across the “Catholic” writings Leibniz consistently identifies two reasons Protestants give for remaining outside the Church: the abuses that prevail there and the Church’s condemnation of opinions that some Protestants sincerely believe to be true. These, we find, are the very same reasons Leibniz had consistently used in his correspondence with the Landgrave when he was pressed on his reluctance to convert. Regarding abuses prevalent in the Catholic Church, Leibniz informed the Landgrave on 23 October/3 November 1682 that “Most of the objections that can be made against Rome are against the practices of people rather than against dogmas, and if these practices were publicly disavowed, these objections would stop” (A I 3, 272). The concern is raised in many other letters; for example, in the first half of March 1684, Leibniz made reference to “…all the vices which are in vogue in the Church, and particularly the immoderate ambition of ecclesiastics, which has caused so many evils” (A I 4, 325); on 24 December 1684/8 January 1685 he claimed: “It is certain ... that the true ways to win over Protestants would have been and still will be the reform of domestic abuses” (A I 4, 341); and on 13/23 March 1685 he told the Landgrave: “It is undoubtedly easier to defend the dogmas rather than the practices accepted in the Roman Church. All the dogmas seem tolerable to me, but there are practices that are hardly so… It is very true that visible abuses most deter Protestants from seeking unity” (A I 4, 357). Thus, the concern about Church abuses that in his “Catholic” writings Leibniz attributes to Protestants was one that he himself shared.

The same is true of the second concern that deters (some) Protestants from entering the Church, namely that the Church condemns views they sincerely believe to be true. When writing to the Landgrave in January 1684, Leibniz gave this as his reason for not converting to Catholicism:

it can happen that in the Church, although infallible in the articles of faith necessary for salvation, some other errors or abuses creep into people’s minds, and by demanding the consent of those who wish to be its members and who believe they have a demonstration of the contrary, the Church places them in the impossibility of being in the external communion, so long as they want to be sincere. For example, when Jansenists were required to sign a proposition of fact, about which they believed they knew the contrary, it was not in their power to obey, even if they had been excluded from the external communion of the faithful. The same applies not only to matters of fact, which depend on the senses, but also to questions that depend upon reasoning. For example, if the Holy Fathers, who believed the roundness of the earth quite absurd and even contrary to the analogy of faith, had demanded the astronomers of their time disavow it, or if the Church of today had demanded from our astronomers the condemnation of the Copernican system. For it is certain that there would have been some excellent astronomers for whom it would have been impossible to comply without dissimulation, since opinion is not something that depends on the power of the will and that can be changed at one’s pleasure.

(A I 4, 320)

Leibniz then claimed to have some philosophical opinions (not specified) for which he believed he had demonstrations, and although he did not think these opinions were “opposed to holy scripture, tradition, or the definition of any council, they are nonetheless disapproved of and sometimes even censured by theologians of the school, who imagine that the contrary is a matter of the faith” (A I 4, 321). Were his opinions to be discovered, he claimed, it could cause a scandal and put him in civil danger. Writing to the Landgrave on 1/11 March 1684, Leibniz again expressed reluctance to convert to Catholicism on account of some of his philosophical opinions (not specified) that he believed would be censured by the Church (A I 4, 321), though in a letter of 7 April 1684 he denied that the opinions he feared would be censured by the Church were “purely philosophical” (LBrF 20, Bl. 2r). And in a letter to the Landgrave of 10/20 October 1684, Leibniz explained that one of the concerns that kept him from converting to Catholicism was that the Roman Church sometimes condemns views that some people sincerely believe to be true, giving the example of the heliocentric theory of Copernicus (A I 4, 336).

It is clear, then, that the arguments against joining the Church that in his “Catholic” writings Leibniz attributes to Protestants are the very arguments that he himself had previously used in letters to the Landgrave when he felt the need to explain why he would not join the Catholic Church. It is perhaps not surprising that, when deciding which Protestant complaints to tackle in his “Catholic” writings, Leibniz would opt for those he had made himself, though this does reinforce the point made in the previous section about his choice of anti-Catholic arguments being idiosyncratic and hardly representative of Protestants of his time. But what is surprising is that, in addition to the arguments that Leibniz attributes to recalcitrant Protestants being the very ones he routinely used when writing to the Landgrave, the responses he gives to these arguments in the “Catholic” writings are borrowed from the Landgrave’s side of the correspondence. Indeed, in one case, Leibniz’s response in the “Catholic” writings is the very response the Landgrave had given to Leibniz’s arguments.

To see this, recall Leibniz’s concern that the Roman Church sometimes condemns views that some people sincerely believe to be true, which Leibniz illustrated with the Copernican hypothesis. On 1/11 November 1684, the Landgrave responded, “have I not told you that I myself, although (as I hope) a good Catholic, hold many and diverse views (nevertheless, with all respect and charity) contrary to certain condemnations by the Inquisitors and the courtiers of Rome?” (A I 4, 337). The Landgrave developed the point in his letter of 10/20 January 1685, reassuring Leibniz that were he to convert and participate in the sacraments of the Church, “no one will bother you about the rest, whether you are for or against Copernicus and whether you have such or such a view on one thing or another. NB, in this matter [sc. Copernicus], not all Catholics are of the same opinion” (A I 4, 344). Needless to say, the Landgrave’s insistence that the Church would tolerate different views on matters of science and philosophy was not an official or received Catholic position, but rather his own personal view. Despite this, Leibniz appropriated it in several of his “Catholic” writings, such as the draft letter to an unnamed Protestant correspondent, “The Proper Starting Point of Our Faith” (both of which also used Copernicus’ heliocentric theory as an example), “On the Unity of the Church”, “On Attempting an Apology for Catholic Truth”, and “The One Catholic Church”, as we have already seen. In crafting these writings, then, Leibniz borrowed the Landgrave’s own response to the very objection Leibniz had himself raised with him in personal correspondence, making it his own.6 We shall shortly see that this is true also of Leibniz’s complaint about Church abuses, his response to that in the “Catholic” writings likewise being borrowed from the Landgrave.

But Leibniz’s explicit borrowing was not the only way in which his “Catholic” writings reflected the Landgrave’s views. To appreciate the links between the Landgrave’s views and those expressed in Leibniz’s “Catholic” writings, it is necessary to consider their correspondence in full. It is well known that the correspondence began on 21 April/1 May 1680 (see A I 3, 243) with a letter from Leibniz, and that it continued until the Landgrave’s death on 2 May 1693 (or rather, just afterwards, as Leibniz’s final letter was sent on 5/15 May 1693, before Leibniz had learned of the Landgrave’s passing; see A I 9, 104–106). Less well-known are the other materials the Landgrave enclosed with his letters to Leibniz. Some of these were copies of letters the Landgrave had sent to or received from others (or copies of letters between others that had otherwise come into his possession), while the rest were various essays of his own composition, either in French or German, usually on one or other of his two favorite subjects: the machinations of European politics and the divisions among Christians, both within and between its various branches and confessions. Only the Landgrave’s essays will concern us here. Many dozens of these are extant; none has yet been published, and to the best of my knowledge, none has yet been discussed in the literature. For this reason, a little more information on them would be useful.

The Landgrave was a prolific writer, and many of his letters to Leibniz were accompanied by several of his own essays, some filling just a few manuscript pages, others between 30 and 40 manuscript pages. What prompted the Landgrave to write all these essays is unclear, though we can probably rule out his correspondence with Leibniz as the proximate cause, for we do not find a close temporal connection between the topics treated in an essay and those treated in his exchanges with Leibniz.7 It is worth bearing in mind that Leibniz was just one of the Landgrave’s many correspondents, among whom were such figures as the Jansenists Antoine Arnauld (1612–1694), Pierre Nicole (1625–1695), and Louis Paul Du Vaucel (1641–1715), the Jesuits François de La Chaise (1624–1709), Cornelius Hazart (1617–1690), and Louis Jobert (d. 1719), and the Lutheran Philipp Jakob Spener (1635–1705), all of whom were much more publicly involved in Christian theology and its controversies than Leibniz was, making them more likely proximate causes for the Landgrave’s essays. Indeed, not only was Leibniz not the stimulus for the Landgrave’s essays, he was also not the only person with whom the Landgrave shared them, as sometimes the essays came to him via a mutual correspondent, such as Anton Ulrich, Duke of Wolfenbüttel (1633–1714) (see for example A I 4, 330).

In some cases, Leibniz had his amanuensis make a copy of an essay the Landgrave had sent before returning the original, while in others he returned the essay without having a copy made. In the former case, there are (at least) two extent copies of the essay: the original, stored with the Landgrave’s papers in the library of Kassel University, and Leibniz’s copy, stored with Leibniz’s papers in the Gottfried Wilhelm Leibniz Bibliothek in Hannover. Many of Leibniz’s letters to the Landgrave contain thanks for the various materials he had been sent and often some remarks on them, sometimes even on materials he did not request his amanuensis to copy. For example, on 31 May 1683, the Landgrave sent Leibniz a short essay entitled “Speculative Curiosity” (UB/LMB 4° Ms. Hass. 248[1a Bl. 357r–358r), in which he wondered what would happen if an ancient monument was discovered with a version of the Apostle’s Creed that was more favorable to Protestants,8 or one more favorable to Catholics.9 When responding to the Landgrave on 4/14 August 1683, Leibniz remarked: “I do not quite understand where the piece entitled ‘Speculative Curiosity’ is going, which supposes or pretends that we have found in the east some old monument favourable to Catholics or Protestants” (A I 3, 318). We may surmise that in the case of this essay, he did not think it worth having a copy made before sending the original back to the Landgrave, though it is uncertain whether this also holds in the other cases when Leibniz did not have a copy made of an essay or other piece the Landgrave had sent him.

Thematically, the Landgrave’s essays have many overlaps with Leibniz’s “Catholic” writings, as should be evident just from the titles of some of the essays the Landgrave wrote in less than one calendar month of 1685:

• “Summary of the Prejudices and Most Important Ideas that the Catholics and Protestants … Have Against Each Other” (10 February 1685, UB/LMB 4° Ms. Hass. 248[2b Bl. 266r–277v (first part) and 278r–284r (second part) [Landgrave’s original]; LBrF 20 Bl. 721–724 [Leibniz’s copy; NB. Leibniz did not have the second part copied]).
• “On the Crime of Schism of the Protestants” (15 February 1685, UB/LMB 4° Ms. Hass. 248[2b Bl. 308–326v [Landgrave’s original]; LH 1, 13 Bl. 13–20 [Leibniz’s copy]).10
• “Brief Discourse on the Question of Whether One Can and Should Always Consider as Damned All Those Who, Although They Are not Recognized as Catholics in the External Forum, Can Yet Nonetheless be Deemed so, According to Charity, in the Internal Forum” (25 February 1685, UB/LMB 4° Ms. Hass. 248[2b Bl. 328r–331v [Landgrave’s original]).
• “Discourse on the Lack of Capacity for Controversies” (3 March 1685, UB/LMB 4° Ms. Hass. 248[2b Bl. 334r–340v [Landgrave’s original]; LBrF 20 Bl. 725–726 [Leibniz’s copy]).

However, while Leibniz’s focus in his “Catholic” writings was what separated Catholics and Protestants, the Landgrave was equally interested in divergent views within Roman Catholicism, about which he wrote much, though often with one eye on the schism between Catholics and Protestants. For example, his “Discourse in the Form of a Dialogue Between Two Catholics on Different Points Which Concern the Church and the Way of Preserving People in its Unity, and on Reuniting Those Who Are Separated from it” (1685) begins like this:

Nothing is more capable of touching all those who have some sense of piety than to consider the evils which have befallen the Church by the division which took place in it around the middle of the last century, and which produced all these different sects which even today keep so many people outside its unity. This naturally leads to searching for the main causes of the great aversion that these people who have separated from the Church have always shown for peace and reunion, and at the same time, what is the best way to cure them of this aversion and bring them back to the unity of the Church, their common mother.

(UB/LMB 4° Ms. Hass. 248[2h Bl. 3r)

Such a passage could easily be inserted into any of Leibniz’s “Catholic” writings without being out of place; indeed, he echoes the same sentiment in many of them. It is not difficult to find other examples in the “Catholic” writings of Leibniz echoing points or claims made by the Landgrave in his essays. For example:

• In “To Be a Member of One of the Three Protestant Religions” (c.1680), the Landgrave wrote that, according to Protestants:

  for at least and almost more than twelve hundred years until the year 1517 the visible and orthodox church of Jesus Christ had perished from the whole earth, and conversely, that all idolatry, superstition, false doctrine, and tyranny, both spiritual and temporal, were in vogue, not only in the western or Roman Church but also in the eastern churches. This goes directly against our Lord’s promise that the gates of hell shall not prevail against His church.

  (LH 1, 7, 6 Bl. 7r [Leibniz’s copy])

  Leibniz echoed this claim in “On the Unity of the Church”, writing that the Protestant view entailed that dreadful corruptions reigned over the whole Church “for twelve and more centuries” (A IV 7, 825).11
• In “Summary of the Prejudices and Most Important Ideas that the Catholics and Protestants ... Have Against Each Other” (10 February 1685), the Landgrave describes as absurd the Protestant principle that simply by invoking the help of the Holy Spirit they will be able to read scripture and draw out the main things they need to believe, regardless of their talents or abilities or how ill-qualified they are for the task (UB/LMB 4° Ms. Hass. 248[2b Bl. 268r [Landgrave’s original]; LbrF 20 Bl. 722r [Leibniz’s copy]).12 Leibniz echoed this assessment in “The Authority of the Church”, describing the Protestant principle as a “paradox”, that is, contrary to accepted wisdom (A IV 3, 282), while in “Apology for Catholic Truth” he described it as “alien to reason” (A IV 6, 740).
• In “Discourse on the Lack of Capacity for Controversies” (3 March 1685), the Landgrave claims that, in order to engage in the controversies, one needs not only a knowledge of scripture, but knowledge of Hebrew, Greek, and Latin, as well as knowledge of the Holy Fathers, profane history, theology, and philosophy; in addition, one must be a good logician and have widely read the books of one’s adversaries (UB/LMB 4° Ms. Hass. 248[2b Bl. 295v [Landgrave’s original]; LBrF 20 Bl. 725r [Leibniz’s copy]). Leibniz echoed this claim in “Apology for Catholic Truth” (A IV 6, 728–729; cf. A IV 3, 282).13

Now, I am not suggesting that Leibniz borrowed these three points from the Landgrave’s essays, as the points are not idiosyncratic or original enough for the Landgrave to have been the only possible source for them. However, because he had read the Landgrave’s essays, Leibniz was aware of the Landgrave’s views and ideas and consequently also aware that he was echoing some of them in his “Catholic” writings.

But Leibniz did borrow at least one thing from the Landgrave’s essays, namely his response to the Protestant complaint about abuses in the Catholic Church. In his essay “Theme and Clarification on What a Fairly Learned Protestant14 Recently Wrote to the Author of the Book Entitled True, Sincere, and Discreet Catholic” (25 November 1682, (UB/LMB 4° Ms. Hass. 248[1b Bl. 623r–672r [Landgrave’s original]; LBrF 20 Bl. 141–160 [Leibniz’s copy]), and an untitled essay on not supporting what is unendurable in the Catholic Church (c. mid-1684, UB/LMB 4° Ms. Hass. 248[2b Bl. 31r–34r), the Landgrave conceded the prevalence of abuses in the Catholic Church but denied that they are grounds for escaping or breaking the unity of the Church (UB/LMB 4° Ms. Hass. 248[1b Bl. 629v and 639v [Landgrave’s original]; LBrF 20 Bl. 144 and 148v [Leibniz’s copy], and UB/LMB 4° Ms. Hass. 248[2b Bl. 31v–32r).15 In “Summary of the Prejudices and Most Important Ideas that the Catholics and Protestants ... Have Against Each Other” (10 February 1685), the Landgrave went further, arguing that the Church will defend only what it formally teaches, not the errant practices of some of its members (UB/LMB 4° Ms. Hass. 248[2b Bl. 274v [Landgrave’s original]; LBrF 20 Bl. 724r [Leibniz’s copy]). Leibniz borrowed these claims in “On the Unity of the Church”, acknowledging abuses but insisting that one should consider not what is done in the Church but its actual teachings (A IV 7, 826).

In pointing out these connections, I do not wish to overstate the similarities between the Landgrave’s essays and Leibniz’s “Catholic” writings. There are, to be sure, great differences between them, not least that the Landgrave’s essays eschew philosophy while many of Leibniz’s “Catholic” writings do not. The Landgrave’s essays also record many of his personal concerns with Catholicism, such as its refusal to allow the faithful to receive communion under both kinds,16 Catholic persecutions of heretics such as the Huguenots,17 and the doctrine of the infallibility of the Pope.18 Such matters do not, however, warrant even a mention in Leibniz’s “Catholic” writings, indicating that he did not intend these writings to fight the Landgrave’s battles, even if he did borrow and echo some of the Landgrave’s opinions when it suited him. This gives us some insight into the extent to which Leibniz felt beholden to the views of a potential patron, namely beholden enough for the patron to be able to see some of his own views reflected in Leibniz’s work, but not so beholden that Leibniz was willing to serve simply as a patron’s mouthpiece or to remove all traces of his own views.

6. The Context of Leibniz’s “Catholic” Writings

As we have seen, there is strong evidence that Leibniz’s “Catholic” writings of 1685 represent a reimagining of his older “Catholic Demonstrations” project, a reimagining for which he envisaged the Landgrave as patron or perhaps even collaborator. But what might have prompted Leibniz to undertake such a project at that time? There is no evidence that it was at the Landgrave’s behest or even with his knowledge. However, events around the probable date of composition—May and June 1685—may afford a clue. Let us, then, consider the context in which the “Catholic” writings were written.

Since 1679, under the auspices of his employer Duke Johann Friedrich and then Duke Ernst August (1629–1698), Leibniz had been engaged in a project to drain the silver mines of the Harz mountains using windmills of his own design. Had the project succeeded, he stood to be rewarded with a lifetime stipend of 1200 talers per year (see A I 2, 202), double his annual salary as court counselor. However, as success proved elusive and costs mounted, on 14 April 1685, Leibniz was advised of Duke Ernst August’s decision to cease work on the Harz project (see A I 4, 189), dashing Leibniz’s hopes of financial security. On 28 May 1685, the duke was informed by Otto Grote, the President of the Chamber of Finances in Hannover, that Leibniz was willing to write the history of the Welf house that would support Duke Ernst August’s dynastic ambitions, and on 22 June Leibniz was charged with the task (see Scheel 1966, pp. 243–45), an arrangement formalized in a resolution from the duke of 10 August 1685 (see A I 4, 205–206). Therefore, between mid-April and the end of June 1685, Leibniz was at something of a loose end in terms of his status in Hannover, having been relieved of one major role that had the potential to bring financial security and yet to be granted another that offered a similar opportunity. He filled some of that time by evaluating, at Duke Ernst August’s request, the genealogical research of the Welfs by Teodoro Damaideno (1655–1690) (see A I 4, 495–496), as well as writing book reviews of Paulus Casatus’ Mechanicorum libri octo (Leibniz 1685a) and Thomas Everard’s Stereometry Made Easie (Leibniz 1685b), the latter review based on Leibniz’s extensive reading notes (see LH 38 Bl. 106–119), as well as maintaining his various correspondences, including that with the Landgrave. Of particular note is that, when writing to the Landgrave on 8/18 May 1685, a few weeks after the collapse of the Harz project, Leibniz requested an incognito meeting. After a series of remarks on how people arrive at their faith and the reasons for thinking that “God established a society whose authority is capable of assuring us”, Leibniz admitted “that there are many reasons that make it probable that there is such a society, but when this society demands things that are not in our power, how can we satisfy it, and it thereby rejects itself and diminishes the probability that other reasons give it.” He then continued:

But I could speak more in-depth about these things and many others when I have the good fortune of paying my respects to Your Serene Highness, and I hope to have this honour soon. This is why I wish to know if you are in Schwalbach or at home, although it seems to me that one is not far from the other. But if I can make this trip, I wish it to be incognito and that Your Serene Highness kindly not say anything even to your people until I have had the pleasure of explaining the reason for it.

(A I 4, 367)

From Leibniz’s remarks, we can surmise that he wanted to discuss with the Landgrave the concern that Protestants wishing to enter the Catholic Church would be required to believe things that were not within their power, a topic treated at length in many of the “Catholic” writings. But we have no record of what Leibniz hoped to accomplish in the meeting, nor any evidence that the meeting ever took place. In fact, it did not, as on 8 August 1685, the Landgrave wrote to Leibniz to say that as he was about to embark on a journey to France, he despaired of seeing Leibniz that year, unless Leibniz came to Frankfurt around the time of the fair (though there is no indication that this happened) (see A I 4, 370).19 Now, of course, the fact that over the course of April–June 1685 Leibniz was relieved of his role at the mines, sought a clandestine meeting with his Catholic correspondent Landgrave Ernst, and wrote a slew of pro-Catholic pieces that borrowed and echoed ideas and arguments from the Landgrave’s writings may all be unrelated. However, it is possible to craft a narrative in which they are not, namely:

When Leibniz was informed that he was to cease his work in the Harz mines (14 April 1685), he cast his mind about for a new project, perhaps even one requiring a new patron or employer. As he was on good terms with the Landgrave, whose deep interest in matters of theological controversy was well known to him, he decided to draft a pro-Catholic piece featuring some of the Landgrave’s ideas alongside his own (May–June 1685). At the very least, Leibniz hoped the Landgrave would serve as patron or sponsor, and perhaps even as contributor or co-author, given the numerous cognate writings the Landgrave had penned in the years since their correspondence had started. Needing to proceed cautiously, lest the plan be discovered by his friends and employer in Hannover, Leibniz requested a secret meeting with the Landgrave in order to discuss it in person (8/18 May 1685). However, when he was charged with writing the Welf history by Duke Ernst August (22 June 1685), his position in Hannover was once again secure, and there was no need to proceed with his Catholic project, which was wound down.

A possible objection to this narrative, or hypothesis, is what we might call the objection from language discrepancy, that is, that the Landgrave wrote his works of theological controversy either in French or German, while all of Leibniz’s “Catholic” writings are in Latin. If Leibniz had envisaged his “Catholic” writings as a project for which the Landgrave would be the patron or even collaborator, one might suppose that he would have written them in French or German, in line with the Landgrave’s own choices when writing essays on a similar theme. And the fact that he did not do so might suggest that while the “Catholic” writings borrowed and echoed some of the Landgrave’s ideas, Leibniz did not intend them for him at all.

This objection has little weight. Leibniz no doubt chose to use Latin for his “Catholic” writings because it was at the time still the lingua franca in Europe, guaranteeing the widest reach. As for the Landgrave’s choice of languages, it is good to remember that his essays were aimed at a select group of correspondents, most of them either German or French nationals, and presumably when writing an essay, he chose which language to use on the basis of the essay’s intended recipients. The Landgrave may not have written much in Latin, but he was certainly versed in the language: he read books written in Latin, and his essays and letters are littered with Latin words, phrases, and sentences. That Leibniz chose Latin for his “Catholic” writings would not have caused any problems of comprehension for the Landgrave and would not have prevented him from patronizing them or even contributing to them, had he wished to do so.

7. Conclusions

Leibniz’s decision to write sometimes in a Catholic voice has often puzzled readers and commentators. The default assumption, given Leibniz’s interest in ecumenical matters and his closeness to some of the figures involved in Church reunion negotiations (namely, Molanus and Spinola), has often been that such writings are contributions to Church reunion, though I have suggested that this claim does not stand up to scrutiny in the case of Leibniz’s 1685 “Catholic” writings. By examining not just these writings but also various others, including many still unpublished, we have seen that the “Catholic” writings are most probably the fruits of a time of great personal uncertainty for Leibniz about his position in Hannover, leading him to reimagine his long-defunct “Catholic Demonstrations” project in a way that would have made it appealing to Landgrave Ernst von Hessen-Rheinfels, from whom Leibniz borrowed some ideas and echoed others, with Leibniz seeing the Landgrave as a potential patron, contributor, or possibly even employer.20 Like the “Catholic Demonstrations”, the successor project from 1685 was conceived first and foremost as an apologetic work rather than as something that would close or eliminate the confessional gap.21

Moreover, if Leibniz had intended the “Catholic” writings to serve Church reunion, it is unlikely that he would have looked to the Landgrave as patron or collaborator, given the Landgrave’s views on the matter. In “Theme and Clarification on What a Fairly Learned Protestant Recently Wrote to the Author of the Book Entitled True, Sincere, and Discreet Catholic” (25 November 1682), the Landgrave identified no fewer than twelve separate requirements he expected Protestants to fulfil for them to be welcomed by the Catholic Church, among which were: accept tradition (both written and unwritten), defer in the interpretation of scripture to the decisions of general councils, recognize and accept in practice the veneration, intercession, and invocation of saints, endorse the doctrine of purgatory, and recognize the primacy of the pope (UB/LMB 4° Ms. Hass. 248[1b Bl. 658v–662r [Landgrave’s original]; LBrF 20 Bl. 155r–158r [Leibniz’s copy]). For the Landgrave, then, Protestants could expect no compromise from Catholics. And consistent with this, he was frosty towards Spinola’s reunion plan: in “Short Memorandum on the Matter of Reunion between Catholics and Lutherans” (1684, UB/LMB 4° Ms. Hass. 248 [2a Bl. 204–207), the Landgrave noted the fierce opposition Spinola’s plan had received from Catholics and Lutherans alike and insisted it would not be welcomed in Rome:

For many reasons, I do not see how it [Spinola’s plan] could ever succeed, and especially how they will want to let it pass in Rome as they will want at least to maintain the formality that they [sc. Protestants] submit themselves absolutely to the Council of Trent, that they profess our faith, and that they pronounce anathema against their accursed reformer, as was done in the past on similar occasions with the Arians and other sectarians. Above all, they will not want to have such Catholics who do not want to accept all seven sacraments, do not hold mass and consecrate without it, and do not believe in transubstantiation at least until the decision of the general council.

(UB/LMB 4° Ms. Hass. 248 [2a Bl. 207v)

Leibniz would thus have been well aware that the Landgrave would have been entirely the wrong choice as patron of or collaborator on a Church reunion project, but a good choice as patron of or collaborator on an apologetic project.

Much is made of Leibniz’s ecumenical credentials, but in the second quarter of 1685, the time of the “Catholic” writings, as well as prior to that, his involvement in Church reunion was minimal, restricted to expressing his hope for Spinola’s proposal (see A I 4, 449 and 510), his concerns about the resistance it had encountered (see A I 4, 452–453), his suspicion that the time was not sufficiently ripe for reunion (see A I 4, 451), and—surprisingly—his private doubts about Spinola’s approach.22 Only in the 1690s would Leibniz become more active in pushing the reunion agenda (for details, see Rudolph 1999), and this principally via his correspondences with Paul Pellisson-Fontanier (1624–1693) and Jacques-Benigne Bossuet (1627–1704), in which he repeatedly made the case for a new ecumenical council, with Trent set aside. Prior to that, Leibniz was more concerned with undertaking apologies for Catholicism, none of which ever came to fruition.