Robert M. Adams claims that Leibniz's rehahilitation of the doctrine of incomplete entities is the most sustained etlort to integrate a theory of corporeal substances into the theory of simple substances. I discuss alternative interpretations of the theory of incomplete entities suggested by Marleen Rozemond and Pauline Phemister. Against Rozemond, I argue that the scholastic doctrine of incomplete entities is not dependent on a hylnmorphic analysis of corporeal suhstances, and therefore can be adapted by Leibniz. Against Phemister, I claim that Leibniz did not reduce the passivity of corporeal substances to modifications of passive aspects of simple substances. Against Adams, I argue that Leibniz's theory of the incompleteness of the mind cannot be understood adequately without understanding the reasons for his assertion that matter is incomplete without minds. Composite substances are seen as requisites for the reality of the material world, and therefore cannot be eliminated from Leibniz's metaphysics.P or Leibniz, a simple substance such as a soul or a mind is a "complete being" in the sense that it is the origin of its own actions, and that it represents in a confused way all its previous states.] Indeed, what could be more complete than a simple substance with its causal independence and autonomy in the production of its own states'! Nevel1heless, in the Addition a l' Explication du systeme nouveau (1698), written as a response to an extended review of the first edition of f イ 。 ョ セ ッ ゥ ウ @ Lamy's De la C0l10iSSallce de soi-mcme," Leibniz embraces the Scholastic view that soul and body, in some sense, are incomplete entities. 3 Although the passages in which Leibniz takes up this thought in subsequent years are not very numerous, Robet1 M. Adams has suggested that it most fully expresses Leibniz's attempt to integrate a Scholastic theory of corporeal substance into his philosophy.4 Marleen Rozemond and Pauline Phemister have proposed interpretations that diverge markedly from Adams'. Rozemond objtcts that Leibniz cannot reproduce basic features of the Scholastic view within the framework of his own metaphysics. According to her interpretation, it is essential for the Scholastic theory that mind and body are related to each other as matter and form, which supplement each other as act and potency -a structure that the relations of mutual representation