Page:Mary Whiton Calkins - Kant's Conception of the Leibniz Space and Time Doctrine (The Philosophical Review, 1897-07-01).pdf/2

Rh monads.” An equally forcible statement is found in the twenty-ninth Epistle: “I believe that extension no more remains when monads are taken away than numbers when things are taken away.” And in the eighth letter occurs the emphatic assertion: “For, though simple substance does not have extension in itself, it nevertheless has position, which is the foundation of extension, since extension is the simultaneous, continuous repetition of position, as we say that a line is formed by the motion (fluctu) of a point.”

The most obvious meaning of these passages clearly is that extension presupposes the spatial, side-by-side existence of monads or simple substances,—or, at least, that extension is related to the monad as the mathematical figure to the point. This is certainly the sense in which Wolff formulated the Leibnizian space theory. It is absolutely impossible, however, to suppose that Leibniz ever entertained any such material view of his monads, however easily some of his unfortunate figurative expressions may be so interpreted. The Leibnizian monads are purely incorporeal, mere centres of spiritual force, never in spatial form or relation. Not merely the whole tenor of the monad doctrine, but definite statements, prove this. The twelfth letter to Des Bosses refers expressly to the assertion just quoted—that “simple substance has position … while extension is the simultaneous, continuous repetition of position”—and explains it by the words, “extension, indeed, has its source in situation (exsurgit ex situ), but adds to situation continuity”; that is, the essence of extension is continuity, though this, like every other phenomenal reality, presupposes the existence of monads. Therefore, Leibniz goes on to say, “I agree that the number of monads increases (augeri), but not as the extension increases.” In other words, the monads are the conditions (requisita), not the ingredients (ingredienta), of body and extension. “It is no more right to say that monads are parts of bodies or touch each other, than to make this assertion about points or about souls.”