Leibniz New Essay Preface

R.I. Raspe and A. G. Kästner had enjoyed several years of joint examination of Leibniz’s manuscripts when, in 1762, Raspe announced the impending publication of a volume of these hertofore suppressed works. The volume was dedicated to Baron Gerlach Adolf von Münchausen.


A. G. Kästner
Kästner’s Preface succinctly propounds the merit of Leibniz’s scientific method. In particular, Kästner took pains to address the thuggish assault on science by Leonhard Euler, which he had fought for two decades. In 1761, in his “Letter to a German Princess,” Euler had bragged about the 1747 “victory” over Leibniz’ Monads.


This is the first English translation of Kästner’s Preface. Its strategic significance is reported in “Leibniz to Franklin on ‘Happiness,’” in this issue. The author's footnotes are in superscript; editor's footnotes are bracketed; and are supplied by David Shavin. It was translated from the French by Nancy Shavin.




Preface to Leibniz's
New Essays on Human Understanding

That the real universe were something altogether different than the apparent one, is a truth that should no longer be in doubt since Descartes, who maintained, to the great astonishment of the philosophers of his time, that light and colors have no similarity to the ideas that we form of them.1 The metaphysics of Leibniz have always seemed to me to be based on this principle.

Those who accuse him of impenetrable obscurity [1] would find it quite clear, if only they would rid themselves of certain prejudices similar to the "intentional species" against which Descartes had to battle. [2] They maintain that the manner in which M. Leibniz has conceived the origin of extension is inexplicable. They prove by geometrical demonstrations, how absurd it is to look at a body as a sum of points. Can one blame for this absurdity, the person to whom the whole continent of Europe is indebted for the infinitesmal calculus? I say this continent—in order to let those rejoice in that liberty, of which they are so jealous—

Deeply divided from the whole world are the British.[3]

It is not body that M. Leibniz composes from simple beings,[4] but the phenomenon of extension, which he accounts for, by saying that we represent to ourselves, indistinctly, a great number of non-extended beings. The telescope shows us clusters of stars, where the naked eye sees only luminous spots. The spot is not composed of stars as the whole is composed of parts: it is an appearance which offers itself to eyes too weak to distinguish the stars. So, the Elements [5] of Leibniz.

G.W. Leibniz

For those who have fought against them [6] with geometrical arguments—which, without doubt, Leibniz could have done as well as they—have they not wasted their time? And those who have claimed that the events of the visible universe could be explained by simple beings—would they not have done better by asking at the outset, how the sensation, which is excited in us by the sun's light, is born of an infinity of sensations of color, which no one before Newton had been bright enough to look for in a ray of sunlight? How can it be that a lady who might not even know the rule of three, feels harmony with a sensitivity, at times more reliable than Euler's calculations of the ratios of vibrations? [7] Let us pursue these two examples, taken at random from an infinity of similar ones, to try to clarify the relationship between the phenomena and their causes [8]: this relationship must be infinitely simpler, than would be the relationship between the visible universe and its Elements.

The representative force, with which Mr. Leibniz has endowed his Elements, seemed dubious even to M. Wolff. Yet, this same Mr. Wolff had brought into the full light of day this truth—that the universe is a whole whose parts are so intimately connected, that one could not change the least thing, without changing the whole into a completely different universe; that it holds together the spider's thread with the same force that pushes or pulls the planets around the sun. This is how a French Philosopher and beautiful spirit2 understood what the German Metaphysician [9] had demonstrated by profound reasoning. Knowning this, could M. Wolff still doubt, that that which happens at each moment to each individual, so affects the universe as a whole, that the infinite mind sees in this, the universe that is, the only one to which an individual, such as he is, could be a part? [10]

If one were to say to someone who is not so well schooled in the science of numbers, that 23 is the 12th term of an arithmetic progression which starts with 1, he will find, first of all, that this progression is one of odd numbers. You need only put in place of the sequence and its given term, the universe and the individual. It is in this sense that I have always understood those "mirrors of the universe" of Leibniz [11], which seemed so ridiculous to many Philosophers, because these gentlemen had no idea how to find an entire sequence from one given term. M. Leibniz used the verb "to represent," as he explains it himself in his remarks on the book of M. Locke now being published.3 The relationship of the circular base of a cone and its section is such that, if you know one, you also know the other. It is thus, that we represent in mechanics, velocities and times by straight lines; thus, that a thermometer represents the warmth of the air, a barometer the weight of the atmosphere.

I had hoped that these reflections would not be altogether misplaced at the beginning of a collection of this great man's philosophical writings, extracted from his manuscripts, many of which are still kept at Hanover to this day. It is up to those who will benefit from it, to acknowledge the protection always so graciously accorded the sciences by the enlightened Ministers to whom the King has confided the happiness of his domains [12], in the care of enriching the republic of letters with these works.

One could not have chosen an editor more worthy than M. Raspe, who combines a solid knowledge with satisfying insights, and who has made every possible effort to make this choice agreeable to the general public. It is for him to instruct the readers concerning some historical circumstances pertinent to this edition. As for me, having had, among many other duties, only a few days to write this Preface, first in Latin as the editor had wished, and then after that to recast it into French, as he thought to ask a little while later, I would hope that I will be pardoned if this Preface is found to be less worthy than the place it holds.

If only I may be permitted to add yet some few more thoughts to which the reading of the following passages has given rise.

In Part II, there is a discussion of the law of continuity in respect to the collision of bodies. M. Euler is of the same mind as M. Leibniz and has, happily, made use of this to calculate the laws of motion.4 [13]

It is also known that M. Leibniz distinguished the species of Ideas more rigorously than anyone before him.5 Hence, one would expect to see him sometimes correct M. Locke, a far less rigorous writer on these matters. Thus, in the investigation of simple Ideas, p. 77 [14]

]. The English Philosopher is as much beneath the German, as the opticians from earlier times, who mistook a ray of sunlight for a simple phenomenon, were beneath Newton. If M. Leibniz had written the history of the human mind, his work would differ from that of M. Locke, as the history of an insect described by Roesel, would differ from a rough draft done by Frisch. [15]

M. Poley enriched his excellent translation of M. Locke's book [16] with observations drawn from the Philosophy of Leibniz and of Wolff. It is a shame that these observations were not written in another language. Perhaps they would have been useful for some minds, who were too superficial to understand M. Locke, and who, in order to pass as Philosophers at very little cost, became extreme admirers of his—imagining themselves as having seen all truths, as the pedants of barbarous ages imagined it with respect to Aristotle. [17]

After the time when the Philosophers were debating the question of the blind man, p. 92 [18], there was an experiment on this which was reported in the Philosophical Transactions.6 At first glance, it appeared to be more in opposition to M. Leibniz, than it was after a more thorough examination. The blind man, who wishes to recognize by sight the bodies that he had distinguished by touch, must, according to M. Leibniz, compare the effects that the surfaces of the bodies have on his two senses. This is what the blind man seemed to do after having been cured by Cheselden, when he took the cat into his hands, which he had not been able to distinguish well enough from the dog, when he was first beginning to see. The observers imagined that he was merely examing the cat with great intensity, whereas, in fact, he was examining it as much with his hands as with his eyes. No one thought of proposing to this young man an experiment with some surfaces as uniform as those of a sphere, or a cube; and it appears that this singular event lacked the presence of sufficiently philosophical observers. His judgement on the paintings was just as Leibniz had predicted. [19]

It is not only nowadays that we have begun to ask if all the rotations of the earth around its axis are equal,7 since M. Leibniz had the same doubt, p. 104. [20]

Are we to believe that, in the most immediately apprehended science [21], the first notion, that of figure, would yet be not well defined? This is nonetheless what is shown, p. 105. [22]

The reader will see by these examples, chosen randomly, whether these works by Leibniz merit the public's attention, and whether, as in the already known writings of the same author, they contain the seeds of truths, which will enrich the cultivation of the republic of letters.

Göttingen, September 1764

The Author's Footnotes

1. Rene Descartes's 1637 Dioptrics, Chapter 1.

2. M. de Maupertuis, Essay de Cosmologie, 1750.

3. Book II, chapter 8, section 12, p. 87.

4. Histoire de l'Academie Royale de Berlin, 1745, p. 37, 51.

5. Gottfried Leibniz's "De cognitione, veritate & Ideis," Acta Eruditorum, Leipzig, 1684.

6. Philosophical Transactions of the Royal Society of London, No. 402; Robert Smith's Compleat System of Optiks, Book 1, chapter 5. [Also, Smith's "On Distinct and Indistinct Vision" was the cause of some debate and notoriety.-N-ed.]

7. See the dissertation of M. Paul Frisius on the daily motion of the Earth, which has won the 1756 prize of the Royal Academy of Berlin.

Editor's Notes

 [1] In particular, Leonhard Euler's 1760/1 Letters to a German Princess and Voltaire's 1759 Candide.

 [2] Medieval, scholastic term. Kästner picks up on Leibniz's attack, that "modern" Newtonians were reviving occultist appeals to innate qualities.

 [3] Latin in text: "Penitus toto divisos orbe Brtiannos."

 [4] I.e., the "Monads."

 [5] I.e., “simple beings” or “Monads.”

 [6] Elements.

 [7] Euler's 1739 Tentamen musicae and 1760/1 Letters. Kästner judos Euler's patronizing, "dumbing-down" approach to ladies. The ear and mind of a woman, or man, can distinguish harmonies, without a supercomputer counting vibrations.

 [8] I.e., where both phenomena and cause are in the visible universe.

 [9] I.e., Leibniz.

[10] Christian Wolff's problem with "representation" included his sensitive theory on the relatedness of the universe, that would not allow him to explain why he himself existed, that is, what God's mission for Wolff was. (Or, to make a business of representing Leibniz, is not to know Leibniz.)

[11] The "Monads."

12] Such is Kästner's description of the role of Baron Gerlach Adolph von Münchausen, Minister to Hanover from the British Court, and leader of the faction for "happiness" for the body politic. (Pierre Beaudry has located a 1766 work by Kästner, in part on "happiness," entitled Nouvelle Theorie des Plaisirs by Sulzer and Kästner.) Münchausen was key in the liberating of the Leibniz documents they published.

13] Kästner alludes to one of the last works written by Euler prior to Maupertuis' arrival at the Berlin Academy in 1745, after which Euler was instructed by Maupertuis, effectively, that Leibniz was now to be treated as a public enemy. Hence, Kästner's reminder to Euler was likely a jab, not a compliment.

14] See "Of Simple Ideas," Book II, Chapter ii, in Leibniz's New Essays.

15] A.J. Roesel von Rosenhof's Historia naturalis ranarum, a massive work on the German frogs and toads, was noted for the vivid artwork, capturing, e.g., muscles in action. J.L. Frisch's Beschreibung von allerley Insecten in Teutschland, also voluminous, was evidently known for its "just the facts, ma'am" style of drawings.

16] Heinrich Eberhard Poley's 1757 German publication of the 1709 abstract of Locke's Essay.

17] Kästner effectively blasts as medievalists, the English followers of Locke, who had such great pretensions as modern defenders of liberty!

18] Found in Leibniz New Essays, Book II, Chapter ix, section 8.

19] William Molyneux, who was engaged in catty comments with Locke about Leibniz, proposed for public consideration: Would a blind adult, upon first being able to see, recognize by sight objects that he had learned by touch? In 1728, the British surgeon William Cheselden removed the cataracts from a 14-year old, who was observed as described above.

[20] Found in Leibniz New Essays, Book II, Chapter xiv, section 21.

[21]I.e, geometry.]

[22] Found in Leibniz New Essays, Book II, Chapter xv, section 4.


208 LETTERS IN CANADA 1996 G.W. Leibniz. New Essays on Human Understanding. Second edition. Edited and translated by Peter Remnant and Jonathan Bennett Cambridge Texts in the History of Philosophy. Cambridge University Press. cxix, 527. us $59.95 doth, us $21.95 paper One of the most useful distinctions by which we organize the history of philosophy is the one dividing rationalists from empiricists. It is remarkable that the seventeenth-century philosophers were so kind as to bisect themselves along lines of both doctrine and geography. The common-sense philosophers of the English world, basing their views on experimental science, the plain testimony of the senses, and the schooling of experience, stand in sturdy opposition to the effete Europeans, wandering in labyrinthinecoils ofpure thought, dreaming up the laws ofnature from armchairs. There is always a distressing amount oftruth in these caricatures ofhistory, but we know it cannot really be so neat; in fact the picture must in many ways be positively misleading. In 1690John Locke published the Essay ConcerningHuman Understanding, which is both the general manifesto and a detailed development of empiricist philosophy. Gottfried Wilhelm Leibniz's New Essays on Human Understanding is an extensive, detailed, but also very wide ranging commentary on Locke's work. It was explicitly intended to elicit a reply from Locke and perhaps could have begun a grand engagement between empiricism and rationalism; between Britain and the Continent. The death of Locke (in 1704, at the age of seventy-two) erased this fascinating historical possibility, and Leibniz shelved the New Essays. It was finally published in 1765 (almost fifty years after Leibniz's death) but not translated into English until 1896, by Alfred Gideon Langley (an edition thatwasnever very widely available). Remnantand Bennett'sversion is the sole alternative, and since its-original publication in 1981 it has entirely superseded Langley's (thoughthis is no measure ofits merit). Remnant and Bennett's original edition was greeted with enthusiasm, but also with the inevitable host of scholarly quibbles and caveats regarding niceties of the translation. The reviews have been read and heeded, and this edition (published in the new CambridgeTexts in the History of Philosophy series) is clearly improved by a number of critically prompted alterations. It is worth repeating, after sixteen years, that Remnant and Bennett have provided a wonderful resource to students of philosophy. Though aimed straight at the classroom, where the New Essays is perfect for illuminating the philosophy of either Locke or Leibniz, or both, it is surprisingly pleasant to read and is characteristically full of all sorts of ideas, fascinating observations, and speculations going far beyond the central disputes between empiricism and rationalism. The errors of the traditional historical divide are evident: Leibniz is the one who favours, understands, and engages in empirical research. Leibniz is the one who is HUMANITIES 209 ' at the forefront of the scientific revolution, reshaping both physics and mathematics in ways undreamt of by Locke. The range of agreement and disagreement, which bears scant similarity to the party lines, also gives the lie to the old dichotomy. The New Essays presupposes much of Leibniz's philosophy and cannot serve as an introduction, but it adds much to our appreciation of that philosophy and reveals how Leibniz could apply it to questions from another's philosophical agenda. It is also delightful to see the scope and freedom of Leibniz's thought. He even gives us hints of our world; of the health sciences he says: 'this aspect of public policy will become almost the chiefconcern of those who govern.' Buthis vision is perhaps inaccurate, for he goes on to qualify that the concern for health will be 'second only to the concern for virtue'! Finally, I raise a small question about Leibniz. Though he was always interested in the emergingmathematical theories of probability andindeed contributed to them, did he ever tmderstand probability? In the New Essays he manages to state correctly the odds fC?r rolling a seven versus rolling a nine, but he is merely lucky. Leibniz is counting I arrangements' of the dice and not their permutations, as revealed by a later remark (in a letter) that one is equally likely to roll a twelve...



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