Book 9
6
For the subject or substrate is distinguishable into two kinds by either being or not being an individual thing. Take for example as the subject of the attributes man, or body or soul, and as an attribute cultured or white. Now the subject, when culture is induced in it, is called not culture but cultured, and the man is called not whiteness but white; nor is he called ambulation or motion, but walking or moving; just as we said that things are of a definite material.
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.
