MONAD (Gr. µovas, unit, from µovos, alone)  , a philosophic term which now has currency solely in its connexion with the philosophy of Leibnitz . In the earlier Greek philosophy the term meant unity as opposed to duality or plurality; at a later time it meant an individual, or, with the Atomists, an atom . It was first used in a sense approximate to that of Leibnitz by Bruno, who meant by it a primary spiritual element as opposed to the material atom . Leibnitz, however, seems to haveborrowed the term not directly from Bruno, but from a con-temporary, Van Helmont the younger . Leibnitz's view of things is that the world consists of monads which are immaterial centres of force, each possessing a certain grade of mentality, self-contained and representing the whole universe in miniature, and all combined together by a pre-established harmony . Material things, according to Leibnitz, are in their ultimate nature composed of monads, each soul is a monad, and God is the monas monadum . Thus monadism, or monadology, is a kind of spiritual atomism . The theory has been revived in recent years by C . B . Renouvier .