"But if you ask a musician or a sculptor or any man of skill, any person, in fact, who has some special work and activity, what the chief good is for him, he will tell you that the chief good is in the work well done. If then man has any special work or function, we may assume that the chief good for man {194} will be in the well-doing of that function. What now is man's special function? It cannot be mere living, for that he has in common with plants, and we are seeking what is peculiar to him. The mere life of nurture and growth must therefore be put on one side. We come next to life as sensitive to pleasure and pain. But this man shares with the horse, the ox, and other animals. What remains is the life of action of a reasonable being. Now of reason as it is in man there are two parts, one obeying, one possessing and considering. And there are also two aspects in which the active or moral life may be taken, one potential, one actual. Clearly for our definition of the chief good we must take the moral life in its full actual realisation, since this is superior to the other. "If our view thus far be correct, it follows that the chief good for man consists in the full realisation and perfection of the life of man as man, in accordance with the specific excellence belonging to that life, and if there be more specific excellences than one, then in accordance with that excellence which is the best and the most rounded or complete. We must add, however, the qualification, 'in a rounded life.' For one swallow does not make a summer, nor yet one day. And so one day or some brief period of attainment is not sufficient to make a man happy and blest." {195} The close relation of this to the teaching of Socrates and Plato need hardly be insisted on, or the way in which he correlates their ideas with his own conception of an actualised perfection. [340] Aristotle then proceeds to a definition of the 'specific excellence' or virtue of man, which is to be the standard by which we decide how far he has fully and perfectly realised the possibilities of his being. To this end he distinguishes in man's nature three modes of existence: first, _feelings_ such as joy, pain, anger; second, _potentialities_ or capacities for such feelings; third, _habits_ which are built upon these potentialities, but with an element of reason or deliberation superadded. He has no difficulty in establishing that the virtue of man must be a habit. And the test of the excellence of that habit, as of every other developed capacity, will be twofold; it will make the worker good, it will cause him to produce good work.