 In Ζ.6, Aristotle goes on to argue that if something is “primary” and “spoken of in respect of itself (kath’ hauto legomenon)” it is one and the same as its essence. The precise meaning of this claim, as well as the nature and validity of the arguments offered in support of it, are matters of scholarly controversy. But it does seem safe to say that Aristotle thinks that an “accidental unity” such as a pale man is not a kath’ hauto legomenon (since pallor is an accidental characteristic of a man) and so is not the same as its essence. Pale man, that is to say, does not specify the “what it is” of any primary being, and so cannot be an essence of the primary kind. As Ζ.4 has already told us, essence, in the primary sense, “will belong to things that are species of a genus and to nothing else” (1030a11–12). Man is a species, and so there is an essence of man; but pale man is not a species and so, even if there is such a thing as the essence of pale man, it is not, at any rate, a primary essence.