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April 10, 2026
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"When Sir A. Fountaine was at Berlin with Leibnitz in 1701, and at supper with the Queen of Prussia, she asked Leibnitz his opinion of Sir Isaac Newton. Leibnitz said that taking mathematicians from the beginning of the world to the time when Sir Isaac lived, what he had done was much the better half; and added that he had consulted all the learned in Europe upon some difficult points without having any satisfaction, and that when he applied to Sir Isaac, he wrote him in answer by the first post, to do so and so, and then he would find it."
"Il y a jusque dans les exercices des enfants ce qui pourrait arrêter le plus grand Mathématicien."
"Pour ce qui est des connaissances non-écrites qui se trouvent dispersées parmi les hommes de différents professions, je suis persuadé qu’ils passent de beaucoup tant à l'égard de la multitude que de l'importance, tout ce qui se trouve marqué dans les livres, et que la meilleure partie de notre trésor n'est pas encore enregistrée."
"TO LOVE is to find pleasure in the happiness of others. Thus the habit of loving someone is nothing other than BENEVOLENCE by which we want the good of others, not for the profit that we gain from it, but because it is agreeable to us in itself. CHARITY is a general benevolence. And JUSTICE is charity in accordance with wisdom. … so that one does not do harm to someone without necessity, and that one does as much good as one can, but especially where it is best employed."
"As regards the objection that possibles are independent of the decrees of God I grant it of actual decrees (although the Cartesians do not at all agree to this), but I maintain that the possible individual concepts involve certain possible free decrees; for example, if this world was only possible, the individual concept of a particular body in this world would involve certain movements as possible, it would also involve the laws of motion, which are the free decrees of God; but these, also, only as possibilities. Because, as there are an infinity of possible worlds, there are also an infinity of laws, certain ones appropriate to one; others, to another, and each possible individual of any world involves in its concept the laws of its world."
"Chaque substance est comme un monde à part, indépendant de toute autre chose, hors de Dieu..."
"Omne possibile exigit existere."
"To love is to be delighted by the happiness of someone, or to experience pleasure upon the happiness of another. I define this as true love."
"Nam filum labyrintho de compositione continui deque maximo et minimo ac indesignabili at que infinito non nisi geometria praebere potest, ad metaphysicam vero solidam nemo veniet, nisi qui illac transiverit."
"Theologus: Amare autem? Philosophus: Felicitate alterius delectari."
"Languages are the best mirror of the human mind [and] the most ancient monuments of peoples."
"quando orientur controversiae, non magis disputatione opus erit inter duos philosophos, quam inter duos computistas. Sufficiet enim calamos in manus sumere sedereque ad abacos, et sibi mutuo (accito si placet amico) dicere: calculemus"
"Musica est exercitium arithmeticae occultum nescientis se numerare animi."
"Plus un, moins un, plus un, moins un, etc. En ajoutant les deux premiers termes, les deux suivans, et ainsi du reste, on transforme la suite dans une autre dont chaque terme est zéro. Grandi, jésuite italien, en avait conclu la possibilité de la création; parce que la suite étant toujours égale à ½, il voyait cette fraction naìtre d'une infinité de zéros, ou du néant. Ce fut ainsi que Leibnitz crut voir l'image de la création, dans son arithmétique binaire ou il n'employait que les deux caractères zéro et l'unité. Il imagina que l'unité pouvait représenter Dieu, et zéro, lé néant; et que l'Être Suprême avait tiré du néant, tous les êtres; comme l'unité avec le zéro, exprime tous les nombres dans ce système. Cette idée plut tellement à Leibnitz, qu'il en fit part au jésuite Grimaldi, président du tribunal des mathématiques à la Chine, dans l'espérance que cet emblème de la création convertirait au christianisme, l'empereur d'alors qui aimait particulièrement le sciences. Je ne rapporte ce trait, que pour montrer jusqu'à quel point les préjugés de l'enfance peuvent égarer les plus grands hommes."
"When the Eleatic School denied the possibility of motion, Diogenes, as everybody knows, stepped forth as an opponent. He stepped forth literally, for he said not a word, but merely walked several times back and forth, thinking that thereby he had sufficiently refuted those philosophers. Inasmuch as for a long time I have been engaged, at least occasionally, with the problem whether a repetition is possible and what significance it has, whether a thing gains or loses by being repeated, it suddenly occurred to me, "Thou canst take a trip to Berlin, where thou hast been before, and convince thyself now whether a repetition is possible and what significance it may have." At home I had almost been brought to a standstill by the problem. Say what one will, it is sure to play a very important role in modem philosophy; for repetition is a decisive expression for what "recollection" was for the Greeks. Just as they taught that all knowledge is a recollection, so will modem philosophy teach that the whole of life is a repetition. The only modem philosopher who had an inkling of this was Leibnitz ."
"Of all the works of Leibnitz, the "Theodicee" is the one most spoken of in Germany. Yet it is his feeblest production. This book, like several other writings in which Leibnitz expresses his religious sentiments, has obtained for its author an evil reputation, and has caused him to be cruelly misunderstood. His enemies have accused him of maudlin sentimentality and weakness of intellect; his friends, in defending, have proved him an accomplished hypocrite. The character of Leibnitz was for long a subject of controversy amongst us : the most partial critics could not absolve him from the accusation of duplicity; his most eager detractors were the freethinkers and the men of enlightenment. How could they pardon in a philosopher defence of the Trinity, eternal punishment, and the divinity of Christ! Their tolerance did not extend so far as that. But Leibnitz was neither fool nor knave, and by the lofty harmony of his intellect he was well able to defend Christianity in its integrity. I say, in its integrity, for he defended it against semi-Christianity. He established the consistency of the orthodox as opposed to the inconsistency of their adversaries. More than this he never attempted. He thus stood at that point of indifference where diverse systems appear as merely different sides of the same truth."
"As to Leibnitz, he is certainly a good philosopher, but in his Theodicée he goes too far and would have all actions necessary. His foreordained harmony is not the least credible nor feasible. If you can get a book entitled: An Essay on the Origin of Evil, by Dr W. King, you will find a much better solution of the question: 'whence comes evil?' Leibnitz does indeed reconcile it all with the goodness of God, but not so reasonably as Dr King."
"As Leibniz was fond of saying, it is one and the same to be a thing and to be a thing. In other words the “really real” is free from otherness, because what we could ascribe to it as other than what it is would actually be “another being.” For the same reason, being as such is free from change. In a doctrine where to be is to be the same, otherness is the very negation of being. Thus in virtue of its self-identity, which forbids it to change unless indeed it ceased to be, true being is immutable in its own right. This permanency in self-identity is the chief mark of the “really real,” that is, of being."
"In the History of Mathematics it is generally stated that the higher analysis took its rise in the method of indivisibles of Cavalieri (1635). This assertion... is erroneous. ...Leibniz was led to his invention of the algorithm of the higher analysis by a study of the writings of Pascal, more than by anything else."
"The German idealist philosophical tradition from which Hayek emerged is usually held to begin with Gottfried Leibniz, who wrote mostly during the second half of the seventeenth century. Leibniz put forward the idea of “monads,” a starkly idealist conception. Essentially, “each monad is a soul,” in the words of Bertrand Russell. Leibniz reversed the traditional conception of mind and matter by applying attributes of matter (in terms of sensory experience) to mind. Mind is what it experiences. Every mind or soul becomes an independent attribute of the universe, divinely ordered or arranged. Leibniz’s focus truly was mind. […] Leibniz was born at the end of the Thirty Years’ War. Religious struggles, such as the Thirty Years’ War, are often protracted and intense because they concern fundamental individual beliefs and values to which compromise is not always applicable. Chaos and disorder reigned in the larger society from which Leibniz emerged. It is not surprising that his philosophy moved in the direction of mind from a strictly sociological perspective, for the world was too hard to bear."
"Perhaps never has a man read as much, studied as much, meditated more, and written more than Leibniz… What he has composed on the world, God, nature, and the soul is of the most sublime eloquence. If his ideas had been expressed with the flair of Plato, the philosopher of Leipzig would cede nothing to the philosopher of Athens."
"When one compares the talents one has with those of a Leibniz, one is tempted to throw away one's books and go die quietly in the dark of some forgotten corner."
"The manuscripts of Leibniz... show, perhaps more clearly than his published work, the great importance which Leibniz attached to suitable notation in mathematics and... in logic generally. He was perhaps the earliest to realize fully and correctly the important influence of a calculus [some mindless method of calculation] on discovery. ...There is a frivolous objection... to the effect that such economy of thought is an attempt to substitute unthinking mechanism for living thought. This contention fails... through the simple fact that this economy is only used in certain circumstances. In no science do we try to make subject to a mechanical calculus any trains of reasoning except such that have not been the object of careful thought many times previously. ...this reasoning has been universally recognized as valid, and we do not wish to waste energy of thought in repeating it when so much remains to be discovered by means of this energy. Since the time of Leibniz, this truth has been recognized, explicitly or implicitly, by all the greatest mathematical analysts."
"The main ideas of his philosophy are to be attributed to his mathematical work, and not vice versa."
"Leibniz was certainly not alone among great men in presenting in his early work almost all the important mathematical ideas contained in his mature work."
"In the interval of 200 years between Kepler and Gauss there arose no great mathematician in Germany excepting Leibniz."
"[T]he program which Immanuel Kant proposed back in the 1760s... was this: our knowledge of the outside world depends on our modes of perception... Unfortunately, a great revolution took place in or about the year 1768, when he read a paper by Euler which intended to show that space was indeed absolute as Newton had suggested and not relative as Leibnitz suggested. (...in the eighteenth century the question of whether Newton's... or Leibnitz's view of the world was right profoundly affected all philosophy.) After reading Euler's argument... Kant... for the first time proposed that... we must be conscious of [absolute space] a priori. ...Kant died in 1804, long before new ideas about space... had been published... And since one of the things that happened in [our] lifetime has been the substitution of... a Leibnitz universe, the universe of relativity, for Newton's universe... we should think that out again."
"Gottfried Leibniz is famous... for his slogan Calculemus, which means "Let us calculate." He envisioned a formal language to reduce reasoning to calculation, and he said that reasonable men, faced with a difficult question of philosophy or policy, would express the question in a precise language and use rules of calculation to carry out precise reasoning. This is the first reduction of reasoning to calculation ever envisioned. ...he actually designed and built a working calculating machine, the Stepped Reckoner ...inspired by the somewhat earlier work of Pascal, who built a machine that could add and subtract. Leibniz's machine could add, subtract, divide, and multiply, and was apparently the first machine with all four arithmetic capabilities."
"Ainsi on peut dire que non seulement l'âme, miroir d'un univers indestructible, est indestructible, mais encore l'animal même, quoique sa machine périsse souvent en partie, et quitte ou prenne des dépouilles organiques."
"Leibnitz, dominated by ideas of communication, is, in more than one way, the intellectual ancestor of the ideas of this book, for he was also interested in machine computation and in automata. My views in this book are very far from being Leibnitzian, but the problems with which I am concerned are most certainly Leibnitzian. Leibnitz's computing machines were only an offshoot of his interest in a computing language, a reasoning calculus which again was in his mind, merely an extention of his idea of a complete artificial language. Thus, even in his computing machine, Leibnitz's preoccupations were mostly linguistic and communicational."
"Leibnitz, though not propounding any full doctrine on evolution, gave it an impulse by suggesting a view contrary to the sacrosanct belief in the immutability of species... His punishment at the hands of the Church came a few years later, when in 1712, the Jesuits defeated his attempt to found an Academy of Science at Vienna."
"The lack of early practice in mathematics left its mark on Leibniz's later mathematical style, in which good ideas are sometimes inefficiently developed through lack of technical skill. Often he seemed to lack not only the technique but also the patience to develop the ideas conceived by his wide-ranging imagination."
"Leibniz's work lacked the depth and virtuosity of Newton's, but then Leibniz was a librarian, a philosopher, and a diplomat with only a part-time interest in mathematics."
"Leibniz's apparent corelessness stands for a fundamental philosophical problem, a quandary that reaches to the foundations of his system of philosophy. In the metaphysics he... presented to the world, Leibniz claimed that the one thing of which we can all be certain is the unity, permanence, immateriality, and absolute immunity to outside influence of the individual mind. In identifying the mind as a "monad"—the Greek word for "unity"—he positioned himself in direct opposition to Spinoza, whose allegedly materialist philosophy of mind he adamantly rejected. And yet the philosopher who made the unity of the individual the fundamental principle of the universe was himself incomparably fragmented, multiplicitous, exposed to the influence of others, and impossible to pin down. How could a monad be so multifarious, not to say nefarious?"
"Long before most of these facts were discovered, Leibnitz had conjectured that originally the earth in general, even in the north, enjoyed a much warmer temperature than in the present period of all-ruling and progressive frost; and Buffon and others have established on this idea their hypothesis of a vast central fire in the interior of the earth. The interior parts of the earth and its internal depths are a region totally impervious to the eye of mortal man, and can least of all be approached by those ordinary paths of hypothesis adopted by naturalists and geologists."
"In Leibniz, a vast edifice of deduction is pyramided upon a pin-point of logical principle. In Leibniz, if the principle is completely true and the deductions are entirely valid, all is well; but the structure in unstable, and the slightest flaw anywhere brings it down in ruins."
"In Locke's own day, his chief philosophical opponents were the Cartesians and Leibniz. ...Until the publication of Kant's Critique of Pure Reason in 1781, it might have seemed as if the older philosophical tradition of Descartes, Spinoza, and Leibniz were being definitely overcome by the newer empirical method. The newer method, however, had never prevailed in German universities, and after 1792 it was held responsible for the horrors of the Revolution."
"Plato, in the Theaetetus, had set to work to refute the identification of knowledge with perception, and from his time onwards almost all philosophers, down to and including Descartes and Leibniz, had taught that much of our most valuable knowledge is not derived from experience."
"[We] will discuss Soul and Body, the doctrine of God, and Ethics. ...We shall find that Leibniz no longer shows great originality, but tends, with slight alterations of phraseology, to adopt (without acknowledgment) the views of the decried Spinoza. We shall find also many more minor inconsistencies than in the earlier part of [Leibniz's] system, these being due chiefly to the desire to avoid the impieties of the Jewish Atheist, and the still greater impieties to which Leibniz's own logic should have led him."
"The principle premisses of Leibniz's philosophy appear to me to be five... : I. Every proposition has a subject and a predicate. II. A subject may have predicates which are qualities existing at various times. (Such a subject is called a substance.) III. True propositions not asserting existence at particular times are necessary and analytic, but such as assert existence at particular times are contingent and synthetic. The latter depend upon final causes. IV. The Ego is a substance. V. Perception yields knowledge of an external world, ie. of existents other than myself and my states. The fundamental objection to Leibniz's philosophy will be found to be the inconsistency of the first premiss with the fourth and fifth; and in this inconsistency we shall find a general objection to Monadism."
"As an interpreter of nature... Leibnitz stands in no comparison with Newton. His general views in physics were vague and unsatisfactory; he had no great value for inductive reasoning; it was not the way of arriving at truth which he was accustomed to take; and hence, to the greatest physical discovery of that age, and that which was established by the most ample induction, the existence of gravity as a fact in which all bodies agree, he was always incredulous, because no proof of it, a priori could be given."
"Substances do not interact. Every substance is eternal. Bodies are phenomena, not independently real. Choices are determined but free. This is the best possible world. I first encountered Leibniz in an introduction to Modern Philosophy and the image of him as a philosopher so enthralled with his reasoning as to deny the reality in front of him stuck with me for a long time. It wasn't that his arguments were bad, but that their conclusions seemed obviously false. Wouldn't a swift kick in the shin suffice to prove that substances do interact, that bodies are real, and perhaps even that this is not the best possible world? This image of Leibniz as naive and detached from reality was cemented by Voltaire's satirical character Dr Pangloss, who insists over and over again - in the face of the worst suffering and injustice - that this is the best possible world. There is some irony in this image of Leibniz, as Leibniz was the far opposite of an 'ivory tower' philosopher. He consistently pursued positions that would increase his political influence over positions that would increase his leisure for study and reflection. Leibniz claimed the progress of knowledge as his main goal, but he approached this goal from two sides, on one side through his own research and writing while on the other side promoting institutions that would better support, disseminate, and apply knowledge. Today, Leibniz is best known or at least most widely read for his philosophical writings, but philosophy represents only a small part of his life's work. Although this book will focus on explaining Leibniz's philosophy, that philosophy must be approached from within the broader context of his life and time."
"The statement is made with certainty: a festival that does not get its life from worship, even though the connection in human consciousness be ever so small, is not to be found. To be sure, since the French Revolution, people have tried over and over to create artificial festivals without any connection with religious worship, or even against such worship, such as the "Brutus Festival" or "Labor Day," but they all demonstrate, through the forced and narrow character of their festivity, what religious worship provides to a festival. […] Clearer than the light of day is the difference between the living, rooted trees of genuine cultic festival and our artificial festivals that resemble those "maypoles," cut at the roots, and carted here and there, to be planted for some definite purpose. Of course we may have to prepare ourselves for the possibility that we are only at the dawn of an age of artificial festivals. Were we [in Germany] prepared for the possibility that the official forces, and especially the bearers of political power, would artificially create the appearance of the festive with so huge an expense in external arrangements? And that this seductive, scarcely delectable appearance of artificial "holidays" would be so totally lacking in the essential quality, that true and ultimate harmony with the world? And that such holidays would in fact depend on the suppression of that harmony and derive their dangerous seduction from that very fact?"
"To experience and live out a harmony with the world, in a manner quite different from that of everyday life — this, we have said, is the meaning of "festival." But no more intense harmony with the world can be thought of than that of "Praise of God," the worship of the Creator of this world. Now, as I have often experienced, this statement is often received with a mixture of discomfort and various other feelings, but its truth cannot be denied. The most festive festival that can be celebrated is religious worship or "cult," and there is no festival that does not get its life from such worship or does not actually derive its origin from this. There is no worship "without the gods," whether it be mardi gras or a wedding."
"Let us now pose the question again: is recourse to the "human" really enough to preserve and firmly ground the reality of leisure? I intend to show that such recourse to mere Humanism is not enough. It could be said that the heart of leisure consists in "festival." In festival, or celebration, all three conceptual elements come together as one: the relaxation, the effortlessness, the ascendancy of "being at leisure" […] over mere function."
"In leisure — not only there, but certainly there, if anywhere — the truly human is rescued and preserved precisely because the area of the "just human" is left behind over and over again — and this is not brought about through the application of extreme efforts but rather as with a kind of "moving away" (and this "moving" is of course more difficult than the extreme, active effort; it is "more difficult" because it is less at one's own disposal; the condition of utmost exertion is more easily to be realized than the condition of relaxation and detachment, even though the latter is effortless: this is the paradox that reigns over the attainment of leisure, which is at once a human and superhuman condition). As Aristotle said of it: "man cannot live this way insofar as he is man, but only insofar as something divine dwells in him." [Nichomachean Ethics X, 7 (1177b27–28)]"
"Leisure stands in a perpendicular position with respect to the working process — in just the same way as the "simple gaze" of intellectus does not consist in the "duration" (so to speak) of ratios working-out process, but instead cuts through it at the perpendicular (the ancients compared the ratio with time, the intellectus with the "always now" of eternity)."
"Leisure lives on affirmation. It […] includes within itself a celebratory, approving, lingering gaze of the inner eye on the reality of creation. The highest form of affirmation is the festival; and according to Karl Kerenyi, the historian of religion, to festival belong "peace, intensity of life, and contemplation all at once." The holding of a festival means: an affirmation of the basic meaning of the world, and an agreement with it, and in fact it means to live out and fulfil one's inclusion in the world, in an extraordinary manner, different from the everyday. The festival is the origin of leisure, its inmost and ever-central source. And this festive character is what makes leisure not only "effortless" but the very opposite of effort or toil."
"Against the exclusiveness of the paradigm of work as activity, first of all, there is leisure as "non-activity" — an inner absence of preoccupation, a calm, an ability to let things go, to be quiet. Leisure is a form of that stillness that is the necessary preparation for accepting reality; only the person who is still can hear, and whoever is not still, cannot hear. […] Leisure is the disposition of receptive understanding, of contemplative beholding, and immersion — in the real."
"Now the code of life of the High Middle Ages said something entirely opposite to this: that it was precisely lack of leisure, an inability to be at leisure, that went together with idleness; that the restlessness of work-for-work's sake arose from nothing other than idleness. There is a curious connection in the fact that the restlessness of a self-destructive work-fanatacism should take its rise from the absence of a will to accomplish something."