Book 7
5
Hence that which is primarily, not in a qualified sense but absolutely, will be substance.
5
Now primary has several meanings; but nevertheless substance is primary in all senses, both in definition and in knowledge and in time. For none of the other categories can exist separately, but substance alone;
6
and it is primary also in definition, because in the formula of each thing the formula of substance must be inherent; and we assume that we know each particular thing most truly when we know what man or fire is— rather than its quality or quantity or position; because we know each of these points too when we know what the quantity or quality is.
7
Indeed, the question which was raised long ago, is still and always will be, and which always baffles us—What is Being?—is in other words What is substance? Some say that it is oneThe Milesians and Eleatics.; others, more than one; some, finiteThe Pythagoreans and Empedocles.; others, infinite.Anaxagoras and the Atomists. And so for us too our chief and primary and practically our only concern is to investigate the nature of being in the sense of substance.
1
Substance is thought to be present most obviously in bodies. Hence we call animals and plants and their parts substances, and also natural bodies, such as fire, water, earth, etc., and all things which are parts of these or composed of these, either of parts or them or of their totality; e.g. the visible universe and its parts, the stars and moon and sun.
