that no man does evil knowingly but only because of ignorance of the good. This doctrine is commonly attacked on the ground that nothing is more common than for a man to know the good and yet do the bad: not knowledge, but habituation or practice, and motive are what is required. Aristotle, in fact, at once attacked the Platonic teaching on the ground that moral virtue is like an art, such as medicine; the experienced practitioner is better than a man who has theoretical knowledge but no practical experience of disease and remedies. The issue turns, however, upon what is meant by knowledge. Aristotle's objection ignored the gist of Plato's teaching to the effect that man could not attain a theoretical insight into the good except as he had passed through years of practical habituation and strenuous discipline. Knowledge of the good was not a thing to be got either from books or from others, but was achieved through a prolonged education. It was the final and culminating grace of a mature experience of life. Irrespective of Plato's position, it is easy to perceive that the term knowledge is used to denote things as far apart as intimate and vital personal realization,—a conviction gained and tested in experience,—and a second-handed, largely symbolic, recognition that persons in general believe so and so—a devitalized remote information. That the latter does not guarantee conduct, that it does not profoundly affect character, goes without saying. But if knowledge means something of the same sort as our conviction gained by trying and testing that sugar is sweet and quinine bitter, the case stands otherwise. Every time a man sits on a chair rather than on a stove, carries an umbrella when it rains, consults a doctor when ill—or in short performs any of the thousand acts which make up his daily life, he proves that knowledge of a certain kind finds direct issue in conduct. There is every reason to suppose that the same sort of knowledge of good has a like expression; in fact 'good' is an empty term unless it includes the satisfactions experienced in
