it is only when the whole is dissolved that they will exist in actuality. In a sense, therefore, all things that are called prior and posterior are so called according to this fourth sense; for some things can exist without others in respect of generation, e.g. the whole without the parts, and others in respect of dissolution, e.g. the part without the whole. And the same is true in all other cases.
Chapter 12
'Potency' means (1) a source of movement or change, which is in another thing than the thing moved or in the same thing qua other, e.g. the art of building is a potency which is not in the thing built, while the art of healing, which is a potency, might be in the man healed, but not in him qua healed. 'Potency ' then means the source, in general, of change or movement in another thing or in the same thing qua other, and also the source of a thing's being moved by another thing or by itself qua other. For in virtue of that principle, in virtue of which the patient suffers anything, we call it 'capable' of suffering; and this we do sometimes if it suffers anything at all, sometimes not in respect of everything it suffers, but only if it suffers a change for the better. — (2) The capacity of performing this well or according to intention; for sometimes we say of those who merely can walk or speak but not well or not as they intend, that they cannot speak or walk. The case of passivity is similar. — (3) The states in virtue of which things are absolutely impassive or unchangeable, or not easily changed for the worse, are called potencies; for things are broken and crushed and bent and in general destroyed not by having a potency but by not having one and by lacking something, and things are impassive with respect to such processes if they are scarcely and slightly affected by them, because of a 'potency' and because they 'can' do something land are in some positive state.
As 'potency ' has so many meanings, 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
