myth of Isis and Osiris, which explained the fertility of the Nile and all other fertility. Greece contributed rites that from time immemorial had been celebrated near Athens. The cult of Mithra, a god of Indo-Iranian origin, was very popular in the army. Others worshiped the Great Mother, of Semitic origin. Given the syncretism of all these religions, soon they were so intermingled that today it is exceedingly difficult for historians to determine which doctrine or practice arose in which context.
