Splitting the Atom

I wonder if anyone saw the significance in the passage from the Categories which I quoted the other yesterday:

Some are in a subject but are not said of any subject. (By 'in a subject' I mean what is in something, not as a part, and cannot exist separately from what it is in.) For example, the individual knowledge-of-grammar is in a subject, the soul, but is not said of any subject; and the individual white is in a subject, the body (for all color is in a body), but is not said of any subject. (Ackrill)

It's a common view that, in the Categories, Aristotle treats substances as unanalyzable 'atoms'. One finds this claim repeated again and again. S. Marc Cohen's statement, from his SEP article, also quoted already (in part), is representative:

The concepts of matter and form, as we noted, are absent from the Categories. Individual substances — this man or that horse — apart from their accidental characteristics — the qualities, etc., that inhere in them — are viewed in that work as essentially simple, unanalyzable atoms. Although there is metaphysical structure to the fact that, e.g., this horse is white (a certain quality inheres in a certain substance), the fact that this is a horse is a kind of brute fact, devoid of metaphysical structure. This horse is a primary substance, and horse, the species to which it belongs, is a secondary substance. But there is no predicative complex corresponding to the fact that this is a horse in the way that there is such a complex corresponding to the fact that this horse is white.

But this is false, isn't it?

Look again at that passage from the Categories. There we find, at the very beginning of the work--when Aristotle is setting down some fundamental distinctions, between substance and accidents, and between particulars and universals--he gives as examples, not "individual knowledge-of-grammar is in the individual man" or "individual whiteness is in the individual man", but rather "individual knowledge-of-grammar is in the soul", and "individual whiteness is in the body."

That is, from the start, Arisotle is prepared to analyze primary substances, when they are living things at least (and these are agreed to be paradigmatic primary substances, for Aristotle) into body and soul.

Cohen is simply incorrect that "this is a horse is a kind of brute fact, devoid of metaphysical structure." No, 'this is a horse' is analyzed into 'this is a soul and a body'.

Tell a story, if you wish, about how Aristotle's use of the form-matter distinction in analyzing substances is a development of the soul-body distinction. But that Aristotle recognizes the possibility and appropriateness of analysis, from the very start, is undeniable.