Kitap 5
8
Impotence is a privation of potency—a kind of abolition of the principle which has been described—either in general or in something which would naturally possess that principle, or even at a time when it would naturally already possess it (for we should not use impotence—in respect of begetting—in the same sense of a boy, a man and a eunuch). Again, there is an impotence corresponding to each kind of potency; both to the kinetic and to the successfully kinetic.
9
Some things are said to be impotent in accordance with this meaning of impotence, but others in a different sense, namely possible and impossible. Impossible means: (a) that whose contrary is necessarily true; e.g., it is impossible that the diagonal of a square should be commensurable with the sides, because such a thing is a lie, whose contrary is not only true but inevitable. Hence that it is commensurable is not only a lie but necessarily a lie.
10
And the contrary of the impossible, i.e. the possible, is when the contrary is not necessarily a lie; e.g., it is possible that a man should be seated, for it is not necessarily a lie that he should not be seated. Possible, then, means in one sense, as we have said, that which is not necessarily a lie; in another, that which is true; and in another, that which may be true.
11
(The power in geometryA square was called a δύναμις. Plat. Rep 587d; Plat. Tim. 31c. is so called by an extension of meaning.)
11
These are the senses of potent which do not correspond to potency. Those which do correspond to it all refer to the first meaning, i.e. a source of change which exists in something other than that in which the change takes place, or in the same thing qua other.
