Abstract: Leibniz often speaks of “corporeal substances.” According to many texts a monad and its organic body are both constituents of a single corporeal substance. This chapter explores the relations among them, and argues for an interpretation of Leibniz's corporeal substances as exhaustively constituted by relations of harmony among simple substances, and thus as consistent with his idealism. It argues also that after 1706, when it came to seem doubtful to both Leibniz and his contemporaries that such an interpretation could provide adequately for the strong unity that all agreed a corporeal substance must have, he tended to back away from the notion of corporeal substance rather than abandon his view of the world as composed ultimately of monads.

Keywords: corporeal substance, harmony, idealism, Leibniz, monad, organic body, simple substances, unity,