Metaphysics

​Substance is spoken of, if not in more ways, at least chiefly in four. For the essence, the universal, and the genus are thought to be the substance of each thing, and the fourth of these is the underlying subject. Now the underlying subject is that of which other things are predicated, while it itself is no longer predicated of anything else. Therefore, we must first determine about this; for the primary underlying subject is thought to be substance in the highest degree. And in one sense matter is said to be of this nature, in another sense form, and in a third that which is composed of these (by matter I mean, for instance, bronze; by form, the shape of its appearance; and by that which is composed of these, the statue as a whole). Therefore, if the form is prior to matter and more truly existing, it will also be prior to that which is composed of both, for the same reason. Now, then, it has been stated in outline what substance is: namely, that which is not predicated of an underlying subject, but that of which other things are predicated. But we must not state it only in this way, for it is not sufficient; for this itself is unclear, and, furthermore, matter becomes substance. For if this is not substance, what else is escapes us; for when other things are stripped away, nothing appears to remain. For the other things are affections, products, and potentialities of bodies, while length, breadth, and depth are certain quantities and not substances (for quantity is not substance); rather, that to which these first belong is substance. But indeed, when length, breadth, and depth are taken away, we see nothing remaining, unless there is something which is bounded by these, so that to those who consider it in this way, matter must appear to be the only substance. By matter I mean that which in itself is said to be neither a “what” nor a quantity nor any other of those things by which being is determined. For there is something of which each of these is predicated, whose being is different from that of each of the predications (for other things are predicated of substance, but this of matter), so that the ultimate thing in itself is neither a “what” nor a quantity nor anything else; nor indeed is it negations, for these also will belong to it only accidentally. For those who consider it from these premises, then, it follows that matter is substance; but this is impossible. For both separability and being a “this” are thought to belong most of all to substance, wherefore the form and that which is composed of both would seem to be substance more than matter. The substance composed of both, then—I mean that composed of matter and form—must be set aside, for it is posterior and obvious; and matter too is in a way clear. But we must consider the third, for this is the most difficult. And some of the sensible things are agreed to be substances, so that we must seek first among these. For it is advantageous to pass to that which is more knowable. For learning proceeds in this way for all, through things that are less knowable by nature to those that are more knowable; and this is the task, just as in practical conduct it is the task to make what is good as a whole good for each out of those things that are good for each, so to make what is knowable by nature knowable to oneself out of those things that are more knowable to oneself. But the things that are knowable to each and primary are often only slightly knowable, and have little or no being; yet we must try to know what is knowable as a whole from what is poorly known but known to oneself, passing, as has been said, through these very things.