"Wherein can consist the unity of that, the formula of which we call a definition, as for instance in the case of man, 'two-footed animal'; for let this be the formula of man. Why, then, is this one, and not many, viz. 'animal' and 'two-footed'? This is how the problem is stated. 'Animal' and 'two-footed' do make a unity, and they should, since: "The definition is a single formula and a formula of substance, so that it must be a formula (...) of some one thing; for substance means a 'one' and a 'this', as we maintain." All the same, there is a need to trace the unity of genus and difference back to its origin, and to see just how this unity differs from others. (shrink)

Aristotle's reasoning in Z, 10-11 has three stages. In the first, Aristotle proposes two different definitions for our consideration. The definitions contrast, at least superficially, for one appears to elucidate a whole by reference to its material parts, while the other does not appear to do so. Aristotle then in effect shows that the form of a whole can be taken in three somewhat different ways: We may be concerned with form by itself, or with the essential determinacy which is (...) form-having- its-formal-effect-in-a-milieu; in the latter alternative, the essential determinacy may be so taken as to be particular or as to be typical. In each of the three cases, form as the primary intelligible is the governing factor. On this basis, it is possible to clarify the character of the two definitions originally proposed as suggestive of a difficulty. (shrink)

Substantial form is a pivotal topic in the Metaphysics. While being is the subject of the entire work, ousiai are the primary cases of being. Among ousiai, individual material things are the ones directly available for examination. Substantial form is the chief determinant of such things. Aristotle assures us, moreover, that an understanding of this type of form will carry us forward, eventually, to an understanding of the formal being which exists totally apart from matter and change--the necessary reality somewhat (...) inadequately discerned by Plato. (shrink)