  According to Leibniz, if the only genuinely real beings are mind-like simple substances, then bodies, motion, and everything else must result from or be derivative of those simple substances and their perceptual states. In a typical statement of his idealism, Leibniz says, “I don't really eliminate body, but reduce [revoco] it to what it is. For I show that corporeal mass [massa], which is thought to have something over and above simple substances, is not a substance, but a phenomenon resulting from simple substances, which alone have unity and absolute reality” (G II 275/AG 181). Yet, this position, denying the reality of bodies and asserting that monads are the grounds of all corporeal phenomena, as well as its metaphysical corollaries has shocked many. Bertrand Russell, for example, famously remarked in the Preface to his book on Leibniz that he felt that “the Monadology was a kind of fantastic fairy tale, coherent perhaps, but wholly arbitrary.” And, in perhaps the wittiest and most biting rhetorical question asked of Leibniz, Voltaire gibes, “Can you really believe that a drop of urine is an infinity of monads, and that each of these has ideas, however obscure, of the universe as a whole?” (Oeuvres complètes, Vol. 22, p. 434) Well, if you are Leibniz, you can. But how so?