Aristotle's Metaphysics Z as First Philosophy

Discussions of Aristotle's Metaphysics Z tend to treat it either as an independent treatise on substance and essence or as preliminary to the main conclusions of the Metaphysics. I argue instead that Z is central to Aristotle's project of first philosophy in the Metaphysics: the first philosopher seeks the first causes of being qua being, espe- cially substances, and in Z Aristotle establishes that essences or forms are the first causes of being of perceptible substances. I also argue that the centrality of Z to first philosophy is compatible with its status as theology.