Book 9
7
Thus where subject has this sense, the ultimate substrate is substance; but where it has not this sense, and the predicate is a form or individuality, the ultimate substrate is matter or material substance. It is quite proper that both matter and attributes should be described by a derivative predicate, since they are both indefinite.
7
Thus it has now been stated when a thing should be said to exist potentially, and when it should not.
1
Now since we have distinguishedAristot. Met. 5.11. the several senses of priority, it is obvious that actuality is prior to potentiality. By potentiality I mean not that which we have defined as a principle of change which is in something other than the thing changed, or in that same thing qua other, but in general any principle of motion or of rest; for nature also is in the same genus as potentiality, because it is a principle of motion, although not in some other thing, but in the thing itself qua itself.Cf. Aristot. Met. 5.4.1.
2
To every potentiality of this kind actuality is prior, both in formula and in substance; in time it is sometimes prior and sometimes not.
2
That actuality is prior in formula is evident; for it is because it can be actualized that the potential, in the primary sense, is potential, I mean, e.g., that the potentially constructive is that which can construct, the potentially seeing that which can see, and the potentially visible that which can be seen.
