Aristotle - index for METAPHYSICA Book 5 Part 12

Potency

Paragraph 1	'Potency' means:
Paragraph 2	(1) a source of movement or change, which is in another thing than the thing moved or in the same thing qua other;
Paragraph 3	(2) the source of a thing's being moved by another thing or by itself qua other.
Paragraph 4	(3) The capacity of performing this well or according to intention;
Paragraph 5	(4) in the case of passivity
Paragraph 6	(5) The states in virtue of which things are absolutely impassive or unchangeable, or not easily changed for the worse, are called potencies;
Paragraph 7	'Potency' having this variety of meanings, so too the 'potent' or 'capable' in one sense will mean that which can begin a movement (or a change in general, for even that which can bring things to rest is a 'potent' thing) in another thing or in itself qua other;
Paragraph 8	Incapacity is privation of capacity - i.e. of such a principle as has been described either in general or in the case of something that would naturally have the capacity, or even at the time when it would naturally already have it;
Paragraph 9	Some things, then, are called adunata in virtue of this kind of incapacity, while others are so in another sense;