 In the seventeen chapters that make up Book Ζ of the Metaphysics, Aristotle takes up the promised study of substance. He begins by reiterating and refining some of what he said in Γ: that ‘being’ is said in many ways, and that the primary sense of ‘being’ is the sense in which substances are beings. Here, however, he explicitly links the secondary senses of ‘being’ to the non-substance categories. The primacy of substance leads Aristotle to say that the age-old question ‘What is being?’ “is just the question ‘What is substance?’” (1028b4).