Such a point of view vividly realized enables us to appreciate the antagonism aroused by the positivistic point of view when it came into conflict with the traditional. The latter was deeply rooted in social habits and loyalties; it was surcharged with the moral aims for which men lived and the moral rules by which they lived. Hence it was as basic and as comprehensive as life itself, and palpitated with the warm glowing colors of the community life in which men realized their own being. In contrast, the positivistic knowledge was concerned with merely physical utilities, and lacked the ardent associations of belief hallowed by sacrifices of ancestors and worship of contemporaries. Because of its limited and concrete character it was dry, hard, cold. Yet the more acute and active minds, like that of Plato himself, could no longer be content to accept, along with the conservative citizen of the time, the old beliefs in the old way. The growth of positive knowledge and of the critical, inquiring spirit undermined these in their old form. The advantages in definiteness, in accuracy, in verifiability were all on the side of the new knowledge. Tradition was noble in aim and scope, but uncertain in foundation. The unquestioned life, said Socrates, was not one fit to be lived by man, who is a questioning being because he is a rational being. Hence he must search out the reason of things, and not accept them from custom and political authority. What was to be done? Develop a method of rational investigation and proof which should place the essential elements of traditional belief upon an unshakable basis; develop a method of thought and knowledge which while purifying tradition should preserve its moral and social values unimpaired; nay, by purifying them, add to their power and authority. To put it in a word, that which had rested upon custom was to be restored, resting no longer upon the habits of the past, but upon the very metaphysics of Being and the Universe. Metaphysics is a substitute for custom as the source and guarantor of higher moral and social values--that is the leading theme of the classic philosophy of Europe, as evolved by Plato and Aristotle--a philosophy, let us always recall, renewed and restated by the Christian philosophy of Medieval Europe.