power of doing the opposite. Its ἐνέργεια cannot issue either in a withholding of its increase or in the production of a noxious weed. So in regard to our senses. This is a case of δύναμις proper. The δύναμις of seeing or of hearing cannot issue in a result the opposite of hearing or of seeing. The capacities of seeing or of hearing terminate respectively in the acts of seeing or of hearing, and cannot terminate in blindness or in deafness, as alternatives equally open to them. These, then, are illustrations of δύναμις properly so called, that is, of δύναμις restricted, to one issue. And that issue follows or obeys the law of the δύναμις that is to say, nothing more than the δύναμις is required to bring about the resulting ἐνέργεια.
27. But suppose that a stone had a capacity for falling upwards as well as downwards. Suppose that wheat had a capacity, not only to grow but to refuse to grow, or that it had a capacity of growing into a noxious weed. Suppose that our eyes, when in their normal state, and when wide open, had a capacity of being blind as well as a capacity for seeing. Suppose that our ears, when their function was entire, had a capacity for being deaf as well as a capacity for hearing. In these cases we should have so many illustrations of what Aristotle calls the δύναμις τῶν ἐναντίων, which, properly speaking, is not a δύναμις at all. These cases are fictitious; but there are real cases of δύναμις τῶν ἐναντίων, the capacity of contraries;
