 In Ζ.11, Aristotle addresses just such a case (although the passage is difficult and there is disagreement over its interpretation). “The form of the human is always found in flesh and bones and parts of this sort,” Aristotle writes (1036b4). The point is not just that each particular man must be made of matter, but that each one must be made of matter of a particular kind—flesh and bones, etc. “Some things,” he continues, “presumably are this in this” (1036b23), i.e., a particular form in a particular kind of matter, so that it is not possible to define them without reference to their material parts (1036b28). Nevertheless, Aristotle ends Ζ.11 as if he has defended the claim that definition is of the form alone. Perhaps his point is that whenever it is essential to a substance that it be made of a certain kind of matter (e.g., that man be made of flesh and bones, and that one “could not make a saw of wool or wood,” Η.4, 1044a28) this is in some sense a formal or structural requirement. A kind of matter, after all, can itself be analyzed hylomorphically—bronze, for example, is a mixture of copper and tin according to a certain ratio or formula (logos), which is in turn predicated of some more generic underlying subject. The reference to matter in a definition will thus always be to a certain kind of matter, and hence to a predicate, rather than a subject. At any rate, if by ‘matter’ one has in mind the ultimate subject alluded to in Ζ.3 (so-called ‘prime matter’), there will be no reference to it in any definition, “for it is indefinite” (1037a27).