The belief in miracles has played a very important part in all the great historical religions. In primitive religions the intervention of powers supposed to be beyond ordinary human control and acting for purposes of their own did not assume the character of supernatural events, for natural and supernatural were not two distinct categories in the primitive religious experience of mankind. It was the process of moralization of religions and the growing knowledge of the consistent working of natural laws that gradually led to a classification of phenomena into the two great divisions of those which were natural and those above nature, a distinction that very soon became an opposition and gave rise to that dualistic conception of life and of the universe which we find at the basis of all the great historical religions.