three hypotheses possible about the book entitled ‘Categories.’ Either it was an early essay written by Aristotle himself, and preserved among his MSS; or it consists of notes from his school, made by some scholar during his lifetime; or else it is the work of some Peripatetic, drawn up after his death, when the making of such tracts had become a fashion. Style is not a sufficient guide in such a question, because the Peripatetics closely imitated the manner of their master. The chief reason for thinking that this book cannot have been his is on account of the extreme nominalism of its doctrine. Aristotle in the ‘Metaphysics’ (VI. vii. 4) asserts that the universal is the “first substance,” while the individual has a secondary and derivative existence; but it is asserted in the ‘Categories’ that the individual is the first substance, and that if individuals were swept away universals would cease to exist. Aristotle may have said this in the early days of his antagonism against Plato;—if so, he seems to have reverted in maturer life to something nearer approaching, though distinguishable from, Plato’s view. There are, however, unphilosophical and un-Aristotelian things in the book — as, for instance, the saying (‘Cat.’ vii. 21) that “if knowledge ceased to exist, the thing known might still remain.” All this looks like the work of a clever but somewhat materialistic follower of the Peripatetic school.
The book which we find standing second in the ‘Organon,’ is the little treatise ‘On Interpretation,’ or, as it might be called, ‘On Language as the interpreter of Thought.’ Its subject is that which in Logic is called
