Aristotle invented the idea of the categories, which are not a classification of things but of predicates: and not a grammatical classification of the predicates of sentences but a classification of what we are predicating of things by means of sentences when we use them to make statements. To make this point, that the categories are categories of predicates not of things, Aquinas prefers to call them the praedicamenta. Whenever we seek to say what sort of thing this is, for Aquinas we are in the
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