Paragraph II. Another division of the subject has yet to be considered: Why should the doctrine that knowledge is sensation, in ancient times, or of sensationalism or materialism in modern times, be allied to the lower rather than to the higher view of ethical philosophy? At first sight the nature and origin of knowledge appear to be wholly disconnected from ethics and religion, nor can we deny that the ancient Stoics were materialists, or that the materialist doctrines prevalent in modern times have been associated with great virtues, or that both religious and philosophical idealism have not unfrequently parted company with practice. Still upon the whole it must be admitted that the higher standard of duty has gone hand in hand with the higher conception of knowledge. It is Protagoras who is seeking to adapt himself to the opinions of the world; it is Plato who rises above them: the one maintaining that all knowledge is sensation; the other basing the virtues on the idea of good. The reason of this phenomenon has now to be examined. By those who rest knowledge immediately upon sense, that explanation of human action is deemed to be the truest which is nearest to sense. As knowledge is reduced to sensation, so virtue is reduced to feeling, happiness or good to pleasure. The different virtues--the various characters which exist in the world--are the disguises of self-interest. Human nature is dried up; there is no place left for imagination, or in any higher sense for religion. Ideals of a whole, or of a state, or of a law of duty, or of a divine perfection, are out of place in an Epicurean philosophy. The very terms in which they are expressed are suspected of having no meaning. Man is to bring himself back as far as he is able to the condition of a rational beast. He is to limit himself to the pursuit of pleasure, but of this he is to make a far-sighted calculation;--he is to be rationalized, secularized, animalized: or he is to be an amiable sceptic, better than his own philosophy, and not falling below the opinions of the world.