Conflicts, conquests, and changes of dynasties seem to have made little difference in the life of the common people. [259] Religion was the thread by which any ruler could lead them; and after the brief destructive outbreak of Cambyses, [260] himself at first tolerant, the Persian conquerors allowed the old faiths to subsist, caring only, like their predecessors, to prevent strife between the cults which would not tolerate each other. [261] The Ptolemies are found adopting and using the native cults as the native kings had done ages before them; [262] and in the learned Greek-speaking society created by their dynasty at Alexandria there can have been at least as little concrete belief as prevailed in the priesthood of the older civilization. It developed a pantheistic philosophy which ultimately, in the hands of Plotinus, compares very well with that of the Upanishads and of later European systems. But this was a hot-house flower; and in the open world outside, where Roman rule had broken the power of the ancient priesthood and Greek immigration had overlaid the native element, Christianity found an easy entrance, and in a declining society flourished at its lowest level. [263] The ancient ferment, indeed, produced many stirrings of relative freethought in the form of Christian heresies to be noted hereafter; one of the most notable being that of Arius, who, like his antagonist Athanasius, was an Alexandrian. But the cast of mind which elaborated the dogma of the Trinity is as directly an outcome of Egyptian culture-history as that which sought to rationalize the dogma by making the popular deity a created person; [264] and the long and manifold internecine struggles of the sects were the due duplication of the older strifes between the worshippers of the various sacred animals in the several cities. [265] In the end the entire population was but so much clay to take the impress of the Arab conquerors, with their new fanatic monotheism standing for the minimum of rational thought.