 The passage in the Metaphysics where Aristotle most obviously addresses this question is vii 11. He begins the chapter by asking “what sorts of thing are parts of the form, and which are not, but are parts of the compound” (1036a26–7). He first discusses the case of things which are realized in multiple different sorts of matter: a circle may be realized in bronze or stone; so it is clear that its matter, bronze or stone, is not part of the form of the circle, since it is separate from them (1036a33–4). We are then told that, in the case of things which are not seen to be separate, nothing prevents the same considerations from applying to them, “even if all the circles that had been seen were bronze” (1036b1).