Consider our friend the silent-film comedian Buster Keaton. Firstly, he is a human; that’s a predication in the category of substance, because it tells you what sort of thing he is. All his essential features will arise from his being this sort of substance, and the only way he can lose these essential features is to stop being a human, in other words, to die—which, I’m sad to report, Buster Keaton did do in 1966.
