Consequently principles and alleged truths are judged more and more by criteria of their origin in experience and their consequences of weal and woe in experience, and less by criteria of sublime origin from beyond everyday experience and independent of fruits in experience. It is no longer enough for a principle to be elevated, noble, universal and hallowed by time. It must present its birth certificate, it must show under just what conditions of human experience it was generated, and it must justify itself by its works, present and potential. Such is the inner meaning of the modern appeal to experience as an ultimate criterion of value and validity. In the third place, great store is set upon the idea of progress. The future rather than the past dominates the imagination. The Golden Age lies ahead of us not behind us. Everywhere new possibilities beckon and arouse courage and effort. The great French thinkers of the later eighteenth century borrowed this idea from Bacon and developed it into the doctrine of the indefinite perfectibility of mankind on earth. Man is capable, if he will but exercise the required courage, intelligence and effort, of shaping his own fate. Physical conditions offer no insurmountable barriers. In the fourth place, the patient and experimental study of nature, bearing fruit in inventions which control nature and subdue her forces to social uses, is the method by which progress is made. Knowledge is power and knowledge is achieved by sending the mind to school to nature to learn her processes of change. In this lecture as in the previous one, I can hardly close better than by reference to the new responsibilities imposed upon philosophy and the new opportunities opened to it. Upon the whole, the greatest effect of these changes up to date has been to substitute an Idealism based on epistemology, or the theory of knowledge, for the Idealism based on the metaphysics of classic antiquity.