If purpose, then, is inherent in art, so is it in Nature also. The best illustration is the case of a man being his own physician, for Nature is like that - agent and patient at once.
The wise man does not expose himself needlessly to danger, since there are few things for which he cares sufficiently; but he is willing, in great crises, to give even his life - knowing that under certain conditions it is not worthwhile to live.
Since the whole city has one end, it is manifest that education should be one and the same for all, and that it should be public, and not private - not as at present, when every one looks after his own children separately, and gives them separate instruction of the sort which he thinks best; the training in things which are of common interest should be the same for all. Neither must we suppose that any one of the citizens belongs to himself, for they all belong to the state, and are each of them a part of the state, and the care of each part is inseparable from the care of the whole.
Conscientious and careful physicians allocate causes of disease to natural laws, while the ablest scientists go back to medicine for their first principles.
Phronimos, possessing practical wisdom . But the only virtue special to a ruler is practical wisdom; all the others must be possessed, so it seems, both by rulers and ruled. The virtue of a person being ruled is not practical wisdom but correct opinion; he is rather like a person who makes the pipes, while the ruler is the one who can play them.