gradually forged the chief doctrines of his philosophy, and a peculiar set of terms in which they were embodied. When he came to write continuously, in his third period, he often assumed these doctrines and terms as already known, having doubtless given them considerable publicity in oral discourse, if not in essays and short treatises which have now been lost. And thus it frequently happens that we meet with terms and doctrines the meaning of which has to be gathered by implication, as it is never explicitly stated. This is the case with Aristotle’s celebrated doctrine of “the Categories,” to which he repeatedly refers, without ever telling us clearly what position in his system it is meant to hold. Perhaps the simplest account of this doctrine is to say that it sprang from an analysis and classification, made by Aristotle, of the things which men speak of. “Category,” in Greek, meant “speaking of” something. Now, when we speak of anything, we shall find (so Aristotle implies) that we are either speaking of “a substance,”—as, for instance, of a particular man; or else that we are asserting something to be the case about something else. And what we can assert about anything else must be either (1) some “quality” it possesses; (2) its “quantity;” (3) some “relation” in which it stands; (4) the “place” of its existence; (5) the “time” of its existence; (6) its “action,” or what it does; (7) its “passion,” or what is done to it; (8) its “attitude;” or (9) its “habit” or dress. “Substance,” and the above nine modes of speaking of it make up the list of the Ten Categories, as enumerated by Aristotle in his ‘Topics’ (I. 9), and also
