and such an example is found in the moral nature of man. We are capable of becoming either virtuous or vicious, and in the same circumstances too. And hence we have no capacity of virtue in the sense in which a stone has a capacity of falling downwards, or in which a man has a capacity of seeing. Of two seeds of the same kind, and placed in the same circumstances, the one cannot grow up an ear of corn and the other a useless weed; but of two men placed in the same circumstances, the one may grow up a virtuous and the other a vicious character. Hence the moral capacity of these two men, and we may say of man generally, is quite different from the physical capacity of things, and quite different from man's physical capacities, all of which are restricted to one issue, and are properly called δυνάμεις, because the acts (ἐνέργειαι) are determined by these capacities and arise out of them. But the others, the δύναμις τῶν ἐναντίων, being capable of issuing in two opposite acts or ἐνέργειαι, are not rightly regarded as δυνάμεις at all. At any rate you must keep in mind the broad distinction between them and the natural δυνάμεις. The δύναμις τῶν ἐναντίων being open indifferently to two issues, has obviously no power of determining its own issue. That issue is determined, not by the δύναμις, but by something else; that something else being, in the case of the moral virtues, the principle of free-will, of which I shall say a word immediately, and the power of custom.
