This chapter introduces a novel interpretation of Aristotle's metaphysics of powers, drawing on various of his works, and putting it in dialogue with alternatives in contemporary metaphysics, thus assessing its relative strengths. The chapter argues that Aristotle held what is currently known as a "pure" power ontology, with no categorical properties at the fundamental level and no categorical base to the fundamental powers. In Aristotle's system, there are no relations relating a power with its manifestation, or with its manifestation partners. Power for Aristotle are relatives, that is, monadic properties of a special kind, whose nature is discussed in the chapter. Their manifestation is governed by conditional necessity. Instances of physical powers are for Aristotle all there is at the foundations of reality.