To be free from the passions and the finite things of the world we must understand their nature; for to understand a thing is to be delivered from it. An illusion is not an illusion when we know it to be such. To see that all the passions, sensations, imaginations, and all the other modes of thought are human limitations, is to dwell within the reason. Spinoza’s freedom is not, as will be seen, freedom in the ordinary psychological meaning of the term, but is the metaphysical freedom of being identical with the deity and determined by no finite thing. Freedom is rational knowledge. Nevertheless, freedom is ethical also, for it consists in overcoming the passions by reason. Freedom, therefore, has two sides: an escape from the emotions and an escape from obscure ideas—the goal in both cases being the life of reason. To attain freedom is to see the world as God sees it, which is the same as the reason sees it. This is to see each finite thing as eternal. Any concrete thing may be regarded by the human being as a finite and isolated thing out of all relation to other objects; or the same thing may be regarded as a detail of infinity. Looked at by itself, a thing is seen partially and falsely, for no finite thing has its explanation in itself. It is, however, seen truly when it is regarded, to use Spinoza’s own celebrated phrase, “under a certain form of eternity” (sub specie aeternitatis). This conception of eternity is one of the most admirable in Spinoza’s teaching. When man rises through the reason to the consciousness of the eternity of the truth of a thing, the thing itself is transformed, and the man himself has gained salvation. Any circle that I may draw is imperfect, every leaf upon the forest trees is defective, all moral activities are wanting, if regarded in their time-limitations. But below all the imperfections of the universe is its absolute mathematical perfectness. There is nothing so abortive and evil that it does not have its aspect of eternity. Side by side with Spinoza’s conception of infinity is his conception of eternity. Infinity is everlastingness, eternity is quality of being. Eternity has no reference to time. One minute may be eternal. The infinity of the substance is one aspect; the eternity of the substance is another. That eternity gained through the reason is salvation and immortality. God is reason, and by the act of the reason do we become one with Him. Our knowledge is, therefore, the measure of our morality. Knowledge and morality are the same; and whatever increases our understanding is morally good; whatever diminishes our understanding is morally wrong.

Nevertheless, from the point of view of the philosopher, there is nothing in the world that is morally good or bad,—nothing which merits his hatred, love, fear, contempt, or pity,—since all that occurs is necessary. The philosopher’s knowledge of the determinism of the world lifts him above the usually conceived world of finite things to this mystic world, reconstructed by his intellectual love of nature or God. Love for God will give to everything its proper value. It is the highest form of human activity. Love for God is an absolutely disinterested feeling, and is not therefore like human love, which is the passing from a less state to a greater. Love for God is peace, resignation, and contentment, for it is oneness with God. In fact, the love of man for God is the love of God for man; it is the love of God for Himself, since man cannot love God without becoming God. Thus man intellectually recognizes his oneness with God, and rejoices. Immortality is absorption in the eternal and necessary substance of the world. It is a common misconception that immortality is duration after death; immortality consists in looking at things under the aspect of eternity. The finite man perishes, but man’s real self, which is God, survives.

Summary of Spinoza’s Teaching. The rationalism of Spinoza is the final word of scholastic realism. It is a mathematical scholasticism in which the attempt is to make clear by the method of deduction all metaphysical problems. That the philosophical teaching of Spinoza is inspiring and ennobling, no one will gainsay. That his philosophy is not clear, is also true. In the beginning of his discussion, spirit is subordinated to nature; at the end, nature is subordinated to spirit. The result is that under the hands of Spinoza God has become a pure abstraction and without content, the world is an illusion, dualism is superseded by a monistic parallelism, individual activity gives way and becomes a pantheistic determinism. Yet amid all this a reconstructed world arises in which man is recompensed for all his losses by his participation in infinity and eternity.

Leibnitz33 as the Finisher of the Renaissance and the Forerunner of the Enlightenment. Leibnitz is the last of the remarkable group of Rationalists of the Renaissance, who so fully represent the spirit of its Natural Science epoch. But Leibnitz also carries us into the next period of modern philosophy—the Enlightenment. He is the transition philosopher. If the reader will examine the dates of his life, he will observe that Leibnitz lived until twenty-five years after the Enlightenment was ushered in by Locke’s Essay on the Human Understanding (1690). But as Leibnitz had already formed his own philosophy by the year 1686, even so versatile a mind as his could not then renounce the Rationalistic point of view for a new one. Some of his writings, such as his Correspondence with Clark and Bayle, his Theodicy, and his New Essays, show that he participated in the new movement of the next period. Yet the majority of his philosophical writings show him to be a Rationalist. Although he may be called the “father of the Enlightenment,” the body of his thought belongs to the Renaissance. His main motive was that which animated all Rationalists—of stating theology in scientific terms. The immediate occasion for his doing this was the political necessity of peace among the religious bodies of Germany.

The effort of Leibnitz to restore the individual to his central place in the universe was a secondary motive. It nevertheless makes him the forerunner of the Enlightenment. Of the Rationalists, Leibnitz speaks for the future, just as Spinoza for the past. Leibnitz unites the Renaissance and the Enlightenment, just as Spinoza joins the Renaissance and the Middle Ages. Spinoza is the Rationalist who utters the final word of scholastic realism, while Leibnitz presages the coming individualism. Spinoza’s philosophy is science buried in traditionalism; Leibnitz’s is science breaking through traditionalism. Spinoza harks back to universals and particulars, substance and forms; Leibnitz points forward to vortex rings, energy, and dynamics. From Leibnitz’s original purpose to rationalize theology, and to succeed where Descartes and Spinoza had failed, there emerges a new motive. He no longer lays the emphasis entirely upon the universal, but he shifts it in part to the particular. The pantheism of Spinoza had systematized the individual out of its reality. Leibnitz’s conception of the individual as dynamic and his conception of the importance of the infinitesimal redeem the individual and bring Leibnitz into more modern times. To classify Leibnitz as a Rationalist is, therefore, not to describe him fully.

The Life and Writings of Leibnitz (1646–1716). Compared with Descartes and Spinoza, Leibnitz had a life that was long in time and rich in experience. Descartes died at 54 and Spinoza at 45, while Leibnitz lived to be 70. In striking contrast with Spinoza’s career, there was no time in the life of Leibnitz after his graduation from the university that he was not in public service. He held the offices that would naturally go to the hanger-on of princes—some of them grandiose ones. While theoretically the interests of the three Rationalists were the same, Leibnitz differed from his predecessors in that his study of philosophical problems always grew out of some practical problem or political occasion. Leibnitz was not an academic thinker, and his “writings were called forth to estimate some recent book, to outline the system for the use of a friend, to meet some special difficulty, or to answer some definite criticism.” Philosophy was only one of the interests of Leibnitz. He was jurist, historian, diplomat, mathematician, physical scientist, theologian, and philologist. Leibnitz was as much at home with the theories of Plato and Aristotle of ancient time, with those of St. Thomas and Duns Scotus of mediæval time, as with the science of Descartes and Galileo. He was precocious, had a prodigious memory and a reactive mind. In the wealth of his information and the productiveness of his genius, he stands with Aristotle as unequaled. Descartes, Spinoza, and Leibnitz belonged to the inner circle of scholars of the time, but Leibnitz was also in personal touch with political affairs and in intimate acquaintance with many of the important rulers. He was in the service of the Elector of Mainz and later of George I of England when George was only Elector of Hanover. He was distinguished by Peter the Great of Russia and Ernst August, Emperor of Germany. He corresponded with Eugene of Savoy and he was ambassador to Louis XIV of France. Sophie Charlotte of Hanover, who married the King of Prussia, was especially interested in him, and he wrote for her his Theodicy. The three great Rationalists came from different strata of society. Descartes was a nobleman’s son, and he voluntarily relinquished the life that Leibnitz was ambitious to enjoy. Spinoza came from the lower class. Leibnitz was the son of a college professor and belonged to the upper middle class. The ambitions of Leibnitz reached for large ends, as often happens among educated people in the middle walks of life. Among other things, he tried to reconcile the Catholics and Protestants, and he tried to universalize language by getting universal characters for all languages.

The literary production of Leibnitz was enormous, consisting of some lengthy works, but mainly of correspondence (at one time with a thousand persons) and of dissertations to learned journals and societies. No one book contains his philosophy—the Monadology coming the nearest to doing so. His most considerable work is his Theodicy. He himself published in book form only two works: his university dissertation on Individuation and the Theodicy.34

In spite of his many successes, the life of Leibnitz was not happy. From death or other causes his noble patrons changed, until he was left without a patron. His life went from bad to worse, and his death occurred almost unnoticed.

The seventy years of Leibnitz’s life fall into four periods. That he passed through three of these periods by the time he was thirty shows the voracity and versatility of his mental powers during their formative and acquisitive state. It also reveals the unusual length of his productive period,—from his thirtieth to his seventieth year. Ten years after his productive period began, when he was forty, he had completed his philosophical theory, so that the last thirty years of his life were free for its elaboration and elucidation, and in part for his departure from it. The details of Leibnitz’s life are as follows:—

1. Leipsic and University Life (1646–1666).

Leibnitz was the son of a professor of the University of Leipsic. He entered the University at the age of fifteen; received his bachelor’s degree at seventeen, and his doctor’s degree at Altdorf at the age of twenty. He was offered a professorship on account of his thesis, but he declined. He published as his bachelor’s thesis, The Principle of Individuation (1663).

2. Mainz and Diplomacy (1666–1672).

Meeting Baron John of Boineburg, who became his patron, Leibnitz went with him to Mainz, and entered the service of the Elector of Mainz. At this time Leibnitz wrote many pamphlets at the Elector’s request, on the religious and political questions of the day. He wrote A New Physical Hypothesis in 1671.

3. Paris and Science (1672–1676).

Leibnitz began this period with a diplomatic mission to the court of Louis XIV in 1672; but during the year both Boineburg and the Elector died, and Mainz was no longer his home nor diplomacy his interest.

He remained in Paris (and London) three years longer, and spent the time in acquiring the “new science.” In Paris he met Arnauld the Cartesian, Tschirnhausen the German mathematician, logician, and most discriminating critic of Spinoza, and he studied with Huyghens the Dutch mathematician. In London he met Boyle, the chemist, Oldenburg, secretary of the Academy of Science, Collins, the mathematician, and he corresponded with Newton. On his return to Hanover he called on Spinoza, who showed him the manuscript of the Ethics.

4. Hanover and Philosophy (1676–1716).

Leibnitz became court councilor and librarian to the Duke of Hanover (Brunswick-Lüneburg). He was involved in a multitude of administrative, historical, and political tasks, and he carried on an enormous correspondence. Among other things he wrote the history of the reigning family, which necessitated his going to Rome and Vienna. In 1684 he published his discovery of the differential calculus, over which arose the celebrated controversy as to whether he or Newton made the prior discovery. In 1686, in his fortieth year, he constructed his philosophical system. However, he showed his affiliation to the coming age by introducing into his system in 1697 the term “monad.” Nearly all his important works were produced in this period. In 1700 he founded the Academy of Sciences in Berlin. He was instrumental in the founding of an academy at St. Petersburg, and he planned academies at Dresden and Vienna.

The Three Influences upon the Thought of Leibnitz.

(1) His Early Classical Studies. The father of Leibnitz, who was a professor of moral philosophy at Leipsic, died when his son was young. Left much to himself, the boy spent his time in his father’s library. At eight years he had acquired Latin; at twelve he had read Seneca, Pliny, Quintilian, Herodotus, Xenophon, Cicero, Plato, the Roman historians, the Greek and Latin fathers. He became so absorbed in scholastic studies that his friends feared that he would not leave them, “not knowing that my mind could not be satisfied with only one kind of thing.” There can be no question that this scholastic training gave him a first hand and sympathetic appreciation of scholastic philosophy. The Aristotelian conception of cosmic purpose, which he got at this time, never left him. Among the writers of the Natural Science Period he alone returned to Aristotle. He made Aristotle’s teleological cause an integral part of his doctrine. His motto finally became, in his Theodicy, “Everything is best in this best of possible worlds.” While for a time he turned from Aristotle to Descartes, in his final construction of his theory he borrowed more from Aristotle.

(2) The New Science and His Own Discoveries. Leibnitz was more fortunate than many of his contemporaries in that his university had already included in its curriculum the study of mathematics. At the age of fifteen he was devoting himself to mathematics at Jena, and he said that the study of Kepler, Galileo, and Descartes made him feel as though “transported into a different world.” Later in life he said of himself, that at fifteen he had decided to give up the scholastic theory of Forms for the mathematical explanation of the world. He became acquainted with the theories of Hobbes and Gassendi in 1670, when he was at Mainz. In 1672, at the age of twenty-six, when he was in Paris, he made himself possessor of all that the celebrated circle of Parisian scientists had to teach. He had gone to Paris a dualist; he returned to his native land with the Aristotelian teleology side by side in his mind with the Spinozistic conception of identity and necessity, the Spinozistic method, and the mathematical theory of the significance of infinitely small particles. The next ten years (1676–1686) were spent in overcoming his own dualism by systematizing these new theories acquired from so many sources. In 1680 he had universalized the concept of force so as to apply it to both souls and bodies. In 1684 he published his discovery of the differential calculus, in which he has had to share honors with Newton. In 1685 he asserted that the centres of force have individuality. He was led to this conclusion on account of the discovery of small organisms by the microscopes of Swammerdam and Leeuwenhoek. In 1686 he successfully organized his collected material into his final system, although it was not until eleven years later (1697) that he called these centres “monads.” Probably he got the term “monad” not from Bruno, but from the mystic chemist, Van Helmont.

Not only the content, but the form of his philosophy was determined by his mathematical studies. His philosophical diction is remarkably lucid. Mathematics reinforced his early resolve “in words to attain clearness and in matter usefulness.” His later discussions contain many terms that he had borrowed directly from mathematics.

(3) Political Pressure for Religious Reconciliation. When Frederick the Wise of Saxony in 1519 refused the crown of Emperor, Germany was thrown into internal strife that in one hundred and thirty years destroyed all its material wealth and depopulated the country. This terminated in the Thirty Years’ War (1618–1648) and the Peace of Westphalia. Leibnitz was born two years before peace was declared. He was the first German scientist in two hundred years. Both Catholics and Protestants were weary of strife, and there was a general movement toward religious reconciliation. Thus religious amity was the most urgent public question.

Pietism had been one of the movements in Germany during the recovery of the country from the Thirty Years’ War, and it represented the best side of German civilization at that time. It was a reaction on the one side against the mechanical theory of the scientists, and on the other against the destructive strife of the old and new confessions. The mother of Leibnitz was not only a Protestant, but also a Pietist, so that the subject of religion early formed an important part of her son’s training. When he entered the diplomatic service of the Elector of Mainz the question of religious reconciliation took practical form for him. No doubt his philosophy as a theory of reconciliation grew out of such practical issues, as they were presented to him at Mainz. Leibnitz had, therefore, a part in the religious reaction in Germany in the last of the seventeenth century, which aimed to reconcile the divergent interests of religion and science. He tried to effect this in no external way, by patching together irreconcilable elements, but in an internal way, by an examination of fundamental principles. With his early training, his theological reading, and his wide public experience, Leibnitz was fitted to take a prominent part in the movement for reconciliation.

The Method of Leibnitz. Although the philosophers who immediately followed Spinoza did not dare to accept his philosophical conclusions, they adopted his method. They united it with the syllogistic processes of formal logic for the deduction of all knowledge. This method became very prevalent, as is seen in the practices of the German Cartesians and in the preparation of academic text-books. Examples of this are Jung, Weigel, who was Leibnitz’s teacher, and Puffendorf, who tried to deduce by the geometrical method the entire system of natural right from a single principle of human need. In the next century Wolff used this method in writing his Latin text-books.

When this aspect of Spinoza’s teaching was gaining a foothold in Germany, Leibnitz came into sympathy with it through his teacher, Weigel, and at first was one of its most ardent supporters. In jest he showed by this geometrical, syllogistic method in sixty propositions that the Count Palatine of Neuberg must be elected King of the Poles. In seriousness he believed that all philosophical controversies would cease when philosophy should be stated like a mathematical calculation.

Hobbes’s theory of words as counters to be used in conceptual reckoning, the universal formulas of the Art of Lull and the pains which Bruno had taken for its improvement, the Cartesian belief that the geometrical method would prove to be an art of invention—all these were influences upon Leibnitz, that committed him to the method of Spinoza and made him pursue that method energetically. Leibnitz was part of the widespread movement of the time to form a Lingua Adamica—a universal language, which should discover fundamental philosophical conceptions and the logical operations of their combinations. In brief, Leibnitz hoped to form a philosophical calculus.

What, asked Leibnitz, are the highest truths which in their combination yield all knowledge? What are the truths, so immediately and intuitively certain, that they force themselves upon the mind as self-evident and thereby form the ground for the deduction of all knowledge? They are of two classes: (1) The universal truths of the reason, and (2) The facts of experience. The truths of the reason are forever true; the facts of experience have a truth for that single instance. But both are true in themselves and not from deduction from anything else. They are “first truths,” for a thing is true if it can be deduced from the reason or tested as an experienced fact. The two kinds of truth are the rational or a priori, and the empirical or a posteriori. The difference between the starting point of the Rationalism of Leibnitz and the Enlightenment of Locke appears here. Locke said, “There is nothing in the mind that does not come from the senses.” “Except the mind itself and its operations,” added Leibnitz in comment.

But there is a difference between these two kinds of truth. The truths of the reason are clear and distinct; the truths of experience are clear but not distinct. Leibnitz is, be it observed, making a distinction between the two terms of the pet phrase of the Rationalists—“clear and distinct ideas.” He means that rational truth is so transparent that it is impossible to conceive its opposite; that empirical truth is only clear, and its opposite is thinkable. It is impossible to think that the three angles of a triangle equal anything but two right angles, but it is possible to think that its side, which is now two inches, may be four inches. Thus emerge the two logical principles upon which Leibnitz founded his philosophy: rational truths depend upon the Principle of Contradiction; empirical truths depend upon the Principle of Sufficient Reason. At first Leibnitz conceived that this distinction between truths did not apply to God, but only to man. Man must rejoice in the few rational truths in his possession and be content with merely establishing the actuality of his experiences. The divine reason can, however, see the impossibility of the opposite both in rational and in empirical truth. Later on Leibnitz conceived the distinction between the two kinds of truth to be absolute. That is, in the nature of things the two truths differ. The rational truth has no opposite, but is a necessary truth; the empirical truth has an opposite, and is a contingent truth.

Leibnitz thus shows the fundamental principles upon which knowledge is based, but what does he say about the logical method of their combination? Nothing. No one would ever suspect from Leibnitz’s philosophical remains that he had planned a system of philosophy according to the method of Spinoza. The many pamphlets of Leibnitz on many scattered subjects show how far short he fell of his ideal of a universal philosophical calculus. He was too versatile, his interests were too diversified, to carry through so slow and plodding a task. He merely stated the principles upon which a systematic symbolic philosophy might rest, without developing these principles in a logical way. Like Bacon, Leibnitz conceived a method that was more of a hope than an accomplishment.

The Immediate Problem for Leibnitz. Perhaps Leibnitz was called away from this purely theoretical problem of method by the practical problem of reconciling science and religion, which problem in his day had become particularly acute. For science had made rapid strides since the days of Descartes, had drawn very far away from religion, and Leibnitz’s attempt to reconcile science and religion was much more difficult than that of the preceding Rationalists. Leibnitz had accepted the most radical results of science, but he saw that science had yielded only a mechanical view of the world. Politics demanded in the exigencies of that hour some principle of unity. He sought to find some philosophical principle for the living, religious character of the universe, and a principle that at the same time would preserve the results of science. He therefore sought to leave the conception of mechanical nature intact and go behind it for a teleological principle. He examined the mechanical principles of the science of his day and found them embedded in a deeper metaphysical principle.

The Result of Leibnitz’s Examination of the Principles of Science35—A Plurality of Metaphysical Substances. What was the developed scientific principle of Leibnitz’s time? And what was the result of his analysis of it? The principle was the mathematical principle of Galileo in more complex form, for there had been added to it since Galileo’s day the concept of the atom. That is to say, the fundamental scientific principle was that nature consists of the measurable movements of atoms. From his analysis of this, Leibnitz obtained as follows his conception of a plural number of substances, which he called monads.

1. Leibnitz first scrutinized the scientific conception of motion. His analysis of motion into infinitely small impulses by the method employed by Galileo, Huyghens, and Newton had already led him to one important discovery—the differential calculus. Now he scrutinizes it further and discovers that the fundamental ground of motion is force. While Leibnitz was in entire agreement with other scientists in their effort to reduce all phenomena to motion, he insisted that motion was not by any means the fundamental thing. He calls the Cartesian conception of motion the antechamber of true philosophy. There is no absolute motion nor absolute rest. Motion and rest are relative to each other. Descartes’ theory that there is conservation of motion is incorrect. Motion and rest are the phenomenal changes of force. Force alone is constant and conserved. Physics points beneath itself to metaphysics; motion points to force. Force is what is fundamental in nature. Force is “that which in the present state of things brings about a change in the future.” Therefore force as the substance of nature is super-spatial and immaterial, and therefore the basis of the new physics ought to be dynamic metaphysical substance.

2. Leibnitz next examined the scientific conception of the atom. Gassendi, one of that celebrated group of Parisian scientists, had been the author of the introduction of Greek atomism into modern thought. It had been generally accepted by scientists and combined with the mathematical hypothesis of Galileo. Leibnitz had known Gassendi in Paris, and he took the hard, inelastic atoms of Gassendi under examination. He agreed that the atomist was perfectly correct in saying that material bodies consist of simple parts or atoms. But Leibnitz insisted that the atomist erred in thinking such simple parts to be physical. However simple the parts might physically appear to be, they were not really simple. However small a bit of matter may be, it may be divided again, and the dividing process may go on to infinity. The atom is the extended, and the extended cannot be simple or real. Substance must be unextended, and the materialists were wrong in attributing substance to the extended. Is there anything simple that has a qualitative character? Is there anything real below the physical atoms? Yes, the metaphysical atoms. The indivisible, immaterial unit lies beneath the physical atom, and in order to reach it we must pass beneath the physical into the metaphysical. This immaterial or metaphysical atom is called by Leibnitz the monad; and thus is Leibnitz’s theory called monadology.

There are three kinds of points, or units, or “simples.” There is the mathematical point, which is simple enough, but it is only imaginary. There is the physical point, or atom, which is real but not simple. There is, lastly, the metaphysical point, or monad, which is both real and simple. The metaphysical point is the only true point. To call the material atoms real, only shows “the feebleness of the imagination, which is glad to rest, and is, therefore, in haste to make an end of division and analysis.”

3. Leibnitz then identified force, as the substance of motion, with the metaphysical atom, as the substance of the material atom. The result was the monad, as he conceived it. The monads are the principles of active working. They are the super-spatial and immaterial principles in which the mechanical principles of the universe have their roots and meaning. Nature is not dead; it is not merely extended. It is alive, resistant, and reproductive. If, as Spinoza taught, there were only one substance, nature would be non-resistant and passive. But as a matter of fact there are many substances acting for themselves, many bodies resisting other bodies. They are the centres of separate activity, and there are as many forces as there are things. There is no body without movement, no movement without force. Thus does Leibnitz reintroduce vitalism in a maturer form than is seen in neo-Platonism. Life becomes the principle of nature. Purpose is placed at the centre of things.

The Double Nature of the Monads. The student will find that the philosophy of Leibnitz is spoken of as a pluralism, but the student will also find that Leibnitz devoted nearly all his strength to prove that the world is after all a unity. Leibnitz analyzed the world into a plural number of parts, and the question then with him was, how to put these parts together again in an organic unity. This accomplishment would depend a good deal upon his conception of the nature of the parts.

The monads have a double character. Leibnitz conceived the monad (1) as a force centre and (2) as an immaterial soul. This makes an equivalence of psychical and physical attributes which reminds us of the Stoics’ “fiery reason” of God. The word “force,” as Leibnitz uses it, squints both toward physics and toward psychology. But such ambiguity about the monads, the cornerstones in Leibnitz’s philosophy, assists Leibnitz’s reconciliation at the start. Here, in a miniature, the physical and spiritual lie in unity. The monad is conceived as a soul-atom.

Leibnitz came to philosophy with a mind saturated with the mathematical ideas of the continuous, the infinitesimal, and the possible. He thought of the monads as potentialities or possibilities. He looked upon the world as essentially a developing world. Behind the facts that seem to us inflexible, lies the great world of generating force. Explanation of the actual can be made only in view of what the actual may be and has been. Let us enlarge the scope of man by so widening his conception of the actual that it will include the possible. Leibnitz also spoke of the monads as infinitesimal. He thereby lifted the conception of the infinitesimal from the realm of mathematics into that of metaphysics, just as Hobbes universalized the conception of mechanics by lifting it to metaphysics. Leibnitz, therefore, did not regard the limits of perception as the limits of nature: the reality of a nature object must be too small to be the object of perception. In the same way he made use of his mathematical conception of continuity. Leibnitz’s conception of nature-continuity is one of his contributions to philosophy. Within itself the world of nature consists of a continuous gradation from the lower to the higher forms; and also the world of nature is continuous with the world of the spirit. There are no leaps in the series from matter to God. Seeming differences in kind are only differences in degree; for example, evil is only the absence of good; matter is only an obscure idea of spirit.

But this Leibnitzian atomism consists of soul-atoms. These monads, these force-centres are souls, and the mathematical qualities have a place in Leibnitz’s description of the psychical powers of the monad. The monad is a soul, for soul is the only substance in the universe that may pass through many changes and it, itself, not change. The self is the only subject of which many predicates may be asserted, while it, itself, may not be the predicate of any other subject. The idea of myself underlies all my mental states. The monad is an entelechy, or an entity having its purpose within itself. All its attributes are contained within itself, and it is, therefore, by nature, sufficient unto itself. It is an individual which passes from one state to another, moved by its “constitutional appetition.”

Among the psychical powers none is more important in Leibnitz’s description of the monad than its power of representation. Representation is the general function of the monad—from the lowest to the highest monad. This means that each monad is the world force, yet in a particular form,—a world substance, but in some peculiar aspect. Every monad is a microcosm. Each represents the world so far as it is conscious of its own activity. But it is evident that all things in the universe are not conscious, and therefore all soul-monads are not conscious. In souls there are, therefore, more than conscious thoughts—there are thoughts that are unconscious. Among the Rationalists Leibnitz is the first to give significance to the so-called unconscious states that form so important a place in modern psychology. (But see Plotinus.) As a wave is composed of small particles of water, so the mind is made up of a myriad of unconscious states. The conscious state is the general effect of the whole. A soul-monad contains in itself at all times representations of the whole world, some obscure, some clear. This power of universal representation makes the monad a microcosm. What we call knowledge of the external world is our representation of it within ourselves. This representation is possible to us because we reproduce it in miniature. Since the monad directly perceives only itself and its own states, it follows that the more clearly and distinctly it is conscious of its own activities, the more adequately does it represent the cosmos. The converse is also true—that the more a monad represents the cosmos, the more truly does it represent itself.

In his development of his description of the monad, Leibnitz hits upon two catch-phrases, one of which presents his doctrine of the physical isolation of the monad, the other presents the doctrine of its ideal psychical unity. These phrases are: “the monads are windowless” and “the monads mirror the universe.” By “windowless” Leibnitz means that each monad is “like a separate world, self-sufficient, independent of every other creature.” “Having no windows by which anything can enter or depart,” the monad can perceive only its own states. Whatever happens to it comes from itself alone as a purely internal principle. The monad’s development is self-development and not the result of external changes. Nevertheless the monad is a “mirror of the universe.” In this psychical qualification of the nature of the monad, its physical isolation vanishes and the way is open for a unity of monads, which would have otherwise seemed to be physically hopelessly sundered. How is it possible for each of the numberless monads, all so different, to “mirror the universe”? The answer is found in their psychical power of representation.

The Two Forms of Leibnitz’s Conception of the Unity of the Substances. The principle of unity among the monads is called by Leibnitz a preëstablished harmony. He presented this principle of harmony in two ways. In part the harmony comes out of their constitution, as he conceived it to be. In part Leibnitz artificially superimposed it upon the monads for theological reasons. In either case it is preëstablished.

The Intrinsic Unity of the Monads—The Philosophical Unity. There is a family resemblance among the monads. The lowest reproduces the universe in obscure and elementary representations. Minerals and plants are sleeping monads with entirely unconscious ideas. Animals are dreaming monads. Man is a waking monad. The highest monad is God, who reproduces the universe in clear and distinct ideas. Between God and matter there is a series of monads, graded as to the clearness of their ideas. All contain the universe by representation. All are bound together according to the principle of continuity; plants are lower animals and animals are less perfect men. Man is a monad whose conscious activity has risen to the height of self-consciousness, with the cognate power of reason. There is no inert matter; no soul-less bodies nor body-less souls. The smallest portion of dust is the habiliment of animalculæ. Nothing is dead, and nature is a gradation of monads in differing degrees of activity.

Metaphysically the monads are isolated, yet in nature as we see them, they live in groups, and compose the things which we call plants, animals, and men. An organic thing is a combination of monads with a central ruling monad. This central monad is the soul of the group; the subordinate ones form the body of the organism. The influence of the soul or ruling monad upon the body-monads is purely ideal. They all strive for the same end, which the soul represents more clearly. The group acts spontaneously and together, not from any outside influence. An inanimate object differs from such a living organism, inasmuch as it is a group of monads without a soul or a ruling, central monad; and therefore such a monad is both soul and body. There is therefore no dualism between soul and body in any creatures, for body is only obscure or unconscious activity. The body consists of monads having a confused sense of their activity.

This continuity and unity within the world, as Leibnitz sees it, is only the logical development of the unity with which he originally endowed his monads. Although he starts the monads as “windowless,” he also says that “they mirror the universe.” They are so conceived as to be originally physically separated, but psychologically and ideally united. “Their natural harmony resides in an ideal of perfect activity, while in actual existence they are independent.” The ideal which unites them is God, the last term in the graded series of the monads. He is the monad of monads, because He is perfect, conscious activity. Just as the various groups of monads are ruled by a central soul-monad, so the world of these groups is an hierarchy, which derives its unitary and harmonious character from this dominating monad. The world may be likened to a pyramid with God at the apex. The world is like a machine which differs from other machines, in that its parts are little machines. Although the parts seem to operate separately, they are under the dominating control of God. God is their intrinsic unity and the universe is a preëstablished harmony.

A comparison with Spinoza’s conception of the world of nature brings out Leibnitz’s meaning effectively. Both philosophers conceive nature phenomena to be under the law of mechanical causation. To Spinoza, however, all phenomena are qualitatively alike; there are no grades or distinctions of value between them. All are modes of substance and all illusions in the sight of God. To Spinoza phenomena are homogeneous. Leibnitz’s estimate of the world of nature is quite different, and for him nature has a far richer endowment. The phenomena of nature are not homogeneous. Their difference does not consist in their content, but in the degree in which they represent the universe. The law of nature is a unifying principle that gives unitary individuality to the members under the law. The individuality of the terms of the nature-series is implied in the very nature of the law of necessity, and on the other hand, the individual terms, for their part, transform the law of necessity into a principle of unity that is higher than bare necessity. In a necessitated series, Leibnitz points out, each term is determined by the preceding, and in turn each term determines the events that follow. Thus, while nature phenomena are a series and a necessitated series, it is a series whose existence depends upon each event having not only its place, but its unique place. No other event can fill that place, and the conditions that give the event its place constitute its individuality. Every finite event has, so to speak, its formula, and this gives individuality to each term of the series, which appeared to Spinoza only as a homogeneous, mathematical, and characterless mode. Life is meaningful to Leibnitz, because each member of the necessitated series of events has its unique part to play. The changes of life are to Spinoza void of meaning, because he conceives them to be undifferentiated. The law of mechanical necessity became under Leibnitz’s hands a principle of harmony, a teleological principle. Even in the necessitated mathematical series, such as Spinoza conceived the world to be, Leibnitz believed that necessity implies individuality and individuality implies purpose.

How vital, therefore, does life now appear, with its mechanical members transformed into living units! Universal striving or force fills nature, and the surging of individual forces gives a new meaning to the unity of the whole. The mechanical series—the physiological changes of our bodies and the efficient causes in nature—are only the expression of the inner teleological development. Leibnitz points out several pregnant principles that are aspects of this preëstablished but intrinsic harmony. In the first place, nature has no breaks and abhors a vacuum; and the series is a continuous one,—the law of continuity. Member follows member in continuous and graded order. Their qualitative differences are differences of quality of activity. Rest and motion, good and evil, are differences of degree. In the second place, there is nothing superfluous; no two things in nature are alike. If they were alike, they would be identical—the law of the identity of indiscernibles. Although there is no absolute antithesis or contrast between things, there is no absolute likeness. Every monad must be differentiated from every other intrinsically, i. e. according to its perfected activity. Therefore, in the third place, every member has an excuse for being—the law of sufficient reason. Every member has its part to perform and no other can act as an understudy for it. However insignificant any member may appear to be, it is as unique as its bigger neighbor.

The Superimposed Unity of the Monads—The Theological Unity. The intrinsic unity of the monads is derived naturally from the monads themselves, but it is an unattained ideal for which they strive. When Leibnitz turns his philosophy into a theodicy, or justification of the nature of God, this unity of the world takes on a different form and assumes a theological importance. The unity is no longer an intrinsic unity, with no actual but only ideal existence depending upon the highest monad in the series, but is an actual personality who exists apart from the world. The world is his eternal purpose. Probably this conception was always in the background of Leibnitz’s thought, but it cannot be deduced from his philosophy. It is a conception afterwards superimposed upon his philosophy. Leibnitz now conceives God not as an ideal goal, but as a perfect and actual person, whose reason impelled Him to construct the best possible world. The world in which we live is the world He chose. It is perfectly conceivable that the world could be different. Why, among all the possible worlds, did God choose to construct this world? There is no reason in logic, but in fact. There was no necessity for its construction. The fact is the excellence of the world. Spinoza said that all possible worlds exist. Leibnitz said this best possible world exists. Look about you; is it not so?

The best possible world is a world of free agents, whose acts are rewarded or punished according to their deserts. If we discover what seems to be inexplicable evil, we must regard it as an incident in the harmony of the whole. The world would be less good without evil. There is no more evil than there ought to be. The world which God conceived to be the best possible—this world—is a world of lights and shades. Evil comes from the free agency of man, and God is not responsible for it. It is better to have evil and free agency than no evil and no free agency. Evil after all is not positive, and is only due to the indistinct ideas of man. It is the absence of good, as cold is the absence of heat.

Thus a preëstablished harmony was constructed by Leibnitz that does not come out of his original philosophical premises. Leibnitz used his celebrated figure of the two clocks to illustrate the harmony of the monads. Two clocks keep the same time, not because they influence one another (interaction), nor because the maker moves the hands of one (Occasionalism), but because they have been thus constructed by an intelligent Creator. Thus the harmony of the world implies a personal God. Leibnitz’s philosophical Rationalism here passed into theology, and his metaphysics became an ethics. Leibnitz began with a monadology, and by means of the conception of harmony passed to an optimism.