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 anindividual 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 andplants 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. Theirdifference 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 surgingof 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 thehighest 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?