              The sufficiency claim is exceptionless, though it may yet be misleading if one pertinent issue is left unremarked. In providing his illustration of the material cause Aristotle first cites the bronze of a statue and the silver of a bowl, and then mentions also ‘the genera of which the bronze and the silver are species’ (Phys. 194b25–27). By this he means the types of metal to which silver and bronze belong, or more generally still, simply metal. That is, one might specify the material cause of a statue more or less proximately, by specifying the character of the matter more or less precisely. Hence, when he implies that citing all four causes is sufficient for explanation, Aristotle does not intend to suggest that a citation at any level of generality suffices. He means to insist rather that there is no fifth kind of cause, that his preferred four cases subsume all kinds of cause. He does not argue for this conclusion fully, though he does challenge his readers to identify a kind of cause which qualifies as a sort distinct from the four mentioned (Phys. 195a4–5). 