knows--that, for Socrates, is the first principle of Ethics, the condition of all moral life. This view is obviously one-sided and essentially individualistic, excluding all those forms of morality which are pursued unconsciously, and are due more to the influence of intuitive perception and social habit than to clear and definite knowledge. The merit of Socrates, however, lies in his demand for ethical reflection, and his insistence upon man not only acting rightly, but acting from the right motive. 2. While Socrates was the first to direct attention to the nature of virtue, it received from _Plato_ a more systematic treatment. Platonic philosophy may be described as an extension to the universe of the principles which Socrates applied to the life of the individual. Plato attempts to define the end of man by his place in the cosmos; and by bringing Ethics into connection with Metaphysics he asks What is the idea of man as a part of universal reality? Two main influences combined to produce his conception of virtue. First, in opposition to the Heraclitean doctrine of perpetual change, he contended for something real and permanent. Second, in antagonism to the Sophistic theory of the conventional origin of the moral law, he maintained that man's chief end was the good which was fixed in the eternal nature of things, and did not consist in the pursuit of transient pleasures. Hence, in two respects, Plato goes beyond Socrates. He puts opinion, which is his name for ordinary consciousness, between ignorance and knowledge, ascribing to it a certain measure of truth, and making it the starting-point for reflection. And further, he transforms the Socratic idea of morality, rejecting the notion that its principle is to be found in a mere calculation of pleasures, {38} and maintaining that particular goods must be estimated by the good of life as a whole. Plato's philosophy rests upon his doctrine of ideas, which, as the types of permanent reality, represent the eternal nature of things; and the problem of life is to rise from opinion to truth, from appearance to reality, and attain to the ideal principle of unity. The highest good Plato identifies with God, and man's end is ultimately to be found in the knowledge of, and communion with, the eternal.