Monadology is undoubtedly Gottfried Wilhelm Leibniz’s best-known work. Because it is a condensed statement of his main philosophical principles, written late in life, there is good reason for this popularity. On the other hand, its popularity is somewhat strange, because Leibniz himself gave no title to the manuscript and it was not published during his lifetime. Written in French in 1714, it was first published in German in 1720. Not until 1840 did the original French version appear, and the title La Monadologie, given to the work at that time, has remained. Although Essais de Théodicée sur la bonté de Dieu, la liberté de l’homme et l’origine du mal (1710; Theodicy: Essays on the Goodness of God, the Freedom of Man, and the Origin of Evil, 1951) represents Leibniz’s philosophical and theological interests more directly, and his Nouveaux essais sur l’entendement humain (wr. 1704, pb. 1765; New Essays Concerning Human Understanding, 1896) undoubtedly provoked more immediate interest, Monadology remains important as a brief metaphysical sketch.

Monadology has been called an “encyclopaedia of Leibniz’s philosophy,” and one of its drawbacks is that in a strict sense, the reader needs to know Leibniz’s other writings in order to understand its contents properly. Support can be found for considering Theodicy to be a more central work from the fact that Leibniz himself added references in the margin of his manuscript (later named Monadology) referring particularly to passages in Theodicy where the views were more fully expressed. Yet Monadology can be, and usually has been, read alone. As such, it stands in a tradition of brief yet comprehensive metaphysical expositions that have an influence out of proportion to their length.


Particularly in view of the fact that Leibniz did not himself title Monadology, the work could just as easily be called “on substance” or “on the modes of being.” In subject matter, Monadology follows the great tradition of metaphysics in trying to define what the ultimate substance of the world is and in trying to arrange a hierarchy to account for all the possible modes of existence. Monadology is divided into ninety brief paragraphs, each summarizing some fundamental point. The first paragraph opens with a description of a monad, thus introducing Leibniz’s most famous doctrine and the single principle in terms of which his entire metaphysics is developed.

Like Baruch Spinoza, whom he knew and admired, Leibniz was impressed with mathematical rigor, and he reflects this love of simplicity and brevity in his philosophical writing. Monadology is not an intricately structured work like Spinoza’s Ethica (1677; Ethics, 1870), but the same love of clarity and of a single First Principle is clearly evident in both. Leibniz, who was equally famous as a mathematician, is read by mathematically and logically inclined philosophers as well as by speculative metaphysicians and theologians.

A monad, Leibniz tells us, is a simple (indivisible) substance that enters into compounds, and a compound is an aggregation of simple things. Monads are the elements of all things, the atoms of all...

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Perception and Apperception

Having covered the basic questions concerning monads as such in eight brief paragraphs, Leibniz then sets forth more general metaphysical principles, built upon the doctrine of the monads as the ultimate simple components of all things. Every created being (and the monad itself is a created thing) is subject to change. All natural changes of the monad come from an internal principle, and the pattern of change that a group of monads characteristically exhibits is its nature. The nature of a thing is its pattern of activity. Perception and apperception (or consciousness) are the two chief types of activity of a monad or of a group of monads, and all activity may be categorized under these two headings. The activity that produces change from one perception to another is what Leibniz calls “appetition,” and nothing but perceptions and their changes can be found in a simple substance like a monad.

Monads have a kind of self-sufficiency, an internalized and purposeful plan of activity, which is what makes them their own source of their internal activities. Because they have this self-directive action as well as perceptions and desires, they may be called souls, although this title is to be reserved only for those whose perception is distinct and is accompanied by memory.

One perception comes only from another perception, as a motion comes only from another motion. Therefore, every present state of a monad is a consequence of its preceding state. So understood, any present moment has within it much more of the future than either the past or the present. Leibniz’s theory of monads, although in a sense deterministic, is a view that is directed primarily toward the future. Certainly all activity and perception have this orientation. However, humans are unique and are to be distinguished from animals, despite the basic similarity between our component parts and theirs. Such a distinction of humans from animals must be based on a distinction of degree; humans have knowledge of necessary and eternal truths, but animals do not.

Reason and Fact

Leibniz began in his theory of monads with a description of a common nature that all things share. Beginning with this separation of humans from animals in virtue of humanity’s knowledge of eternal truths, Leibniz concentrates primarily on humanity and God, and for this reason the common, shared substance receives less emphasis. For humans, knowledge of necessary and eternal truths raises them to a knowledge of themselves and of God. Reflective self-consciousness has been introduced. People have a knowledge of necessary truths, and they may think about God’s nature—all of which requires a unique type of reasoning.

People’s reasoning is founded on two great principles: the principle of contradiction, which separates the true from the false, and the principle of sufficient reason. The latter tells us that for every fact there is a reason sufficient to account for the fact regardless of whether the reason can be known. Truths in turn are to be divided into two kinds: those of reasoning and those of fact. Truths of reasoning are necessary, and their opposite is impossible; truths of fact are contingent, and their opposite is possible.

The Nature of God

Leibniz then offers his arguments for God’s existence. The sufficient or final reason for things must be outside the sequence or series of particular contingent things, however infinite the series may be. Thus, the final reason for all things must be a necessary substance, and this substance is called God. There needs to be only one God because this God is sufficient to account for the variety of particulars.

Such a God is absolutely perfect because perfection as Leibniz defines it is nothing but the presence of positive reality, and God, as an unlimited sequence of possible beings, must contain as much reality as possible. To separate humanity from God, Leibniz asserts that created beings derive their perfections from God but their imperfections from themselves because God is infinite but humanity must be limited. God’s infinity seems to be the chief source of his perfection and is the quality that separates him most radically from humanity because both are composed of basically similar monads.

Leibniz modifies Saint Anselm’s ontological argument for God’s existence. Instead of using Anselm’s phrase, “necessary existence,” Leibniz writes, “He must necessarily exist, if He is possible.” This changes Anselm’s point and shifts the question of God’s existence to one of demonstrating the possibility of a God. Nothing can interfere with the possibility of an infinite God’s existence (this part of the reasoning is traditional), but the possibility of a God must first be established (this is new).

One of Leibniz’s most famous, and disputed, doctrines is that of the creation of monads. He has asserted that none can be brought into being or destroyed by natural causes, but this leaves open the question of a divine origin. God, it turns out, is the only uncreated monad; all the rest are created or derivative. This process Leibniz calls “fulguration,” and it seems to be not a single act but an activity of God continued from moment to moment. Because no further explanation of this important doctrine of the origin of monads is given nor any further definition of the key term “fulguration” (except a reference to Theodicy), this theory of Leibniz has been the source of much discussion.

The Best of All Possible Worlds

Only through the mediation of God can one monad affect another; and one affects another only in the sense that, in predestinating things from the beginning, God may have considered one monad in determining the activity of another in relation to it. God is said to have a “will” that regulates things according to a principle of the best, but this does not allow him any alternatives in design. This is Leibniz’s most famous doctrine, that God has in fact created the best world which it was possible for him to devise.

God does have an infinite number of possible universes to choose from, it is true, but only one of them could become actual through his creative activity. Fitness, or degree of activity in perfection, determines him, so that in that sense his activity in creation is not really free. When all that must be considered and balanced is included, there are no alternatives to the world he did create. His goodness makes him choose it, and his power makes him produce it.

People are not at all cut off in this world. Each living thing is a perpetually living mirror of the universe. It sometimes seems as if people live in many different worlds, but these are in truth nothing but aspects of a single universe, viewed from the special point of view of each monad. Being joined in this way, people are not really independent. Everybody feels the effect of all that takes place in the universe. Each created monad thus represents the whole universe within itself. All nature shares in this interconnectedness, down to matter itself. There is nothing fallow, nothing sterile, nothing dead in the universe, no chaos, no confusion save in appearance.

Preestablished Harmony

God alone is completely without body, although this means merely to be a monad of a special type. The births and deaths of natural bodies are not abrupt transitions (no transition for Leibniz is abrupt). Birth and death are gradual changes. Body and soul both follow their own laws (no soul is without body except God). The body and soul of any entity agree, despite their variant laws, through the “preestablished harmony” of all substances that God has arranged. This is a modern metaphysical version of the traditional theological doctrine of foreordination. Souls act according to the laws of final causes through appetitions, ends, and means. Bodies act according to the laws of efficient causes or motions. Through God’s original...

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Monadology in Context

One thing that should be noted is that the famous doctrine of the monads occupied only the first part of the unnamed treatise, and in the later sections the traditional theological problems are taken up with less and less mention made of the theory of the monads. Monadology is not the tightly knit and interlocking statement of doctrine it is often thought to be. Within this brief treatise many important theories are merely mentioned; few are argued at all. More independence probably exists between the various theories here than is often recognized, and certainly other of Leibniz’s writings need to be studied (primarily Theodicy) before any appraisal at all can be made. What is to be found within the ninety brief...

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Additional Reading

Adams, Robert Merrihew. Leibniz: Determinist, Theist, Idealist. New York: Oxford University Press, 1994. An important philosopher of religion explores Gottfried Wilhelm Leibniz’s philosophical theology and its views regarding evil, goodness, and the nature of God.

Aiton, E. J. Leibniz: A Biography. Boston: A. Hilger, 1985. A worthwhile account of Leibniz’s life, including his place in the scientific, philosophical, and religious worlds of his time.

Copleston, Frederick. A History of Philosophy: Modern Philosophy. Garden City, N.Y.: Doubleday, 1964....

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