The justification of a wholly non-Humean conceptual scheme, based upon the idea of enduring individuals with powers, rests in part on the success of such a scheme in resolving the problems bequeathed to us by the Humean tradition and in part must be achieved by a careful construction of the metaphysics of the new scheme itself. By this we mean a thorough exposition of the meaning and interrelations of the concepts of the new scheme. It is to the latter task (...) that we turn in this paper, being satisfied that the power of the scheme to give a rational account of science has been shown, and that its effectiveness in resolving the Humean problems and dilemmas has been amply demonstrated. (shrink)