Abstract

"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.