have mentioned, sometimes mean being potentially, and sometimes being actually. For we say both of that which sees potentially and of that which sees actually, that it is 'seeing', and both of that which can use knowledge and of that which is using it, that it knows, and both of that to which rest is already present and of that which can rest, that it rests. And similarly in the case of substances we say the Hermes is in the stone, and the half of the line is in the line, and we say of that which is not yet ripe that it is corn. When a thing is potential and when it is not yet potential must be explained, elsewhere.[1]
Chapter 8
'Substance' means (1) the simple bodies, i.e. earth and fire and water and everything of the sort, and in general bodies and the things composed of them, both animals and divine beings, and the parts of these. All these are called substance because they are not predicated of a subject but everything else is predicated of them. — (2) That which, being present in such things as are not predicated of a subject, is the cause of their being, as the soul is of the being of animals.[2] — (3) The parts which are present in such things, limiting them and marking them as individuals, and by whose destruction the whole is destroyed, as the body is by the destruction of the plane, as some say, and the plane by the destruction of the line; and in general number is thought by some to be of this nature; for if it is destroyed, they say, nothing exists, and it limits all things. — (4) The essence, the formula of which is a definition, is also called the substance of each thing.
It follows, then, that substance has two senses, (a) the ultimate substratum, which is no longer predicated of anything else, and (b) that which is a 'this' and separable[3] — and of this nature is the shape or form of each thing.
