It was only in early custom and cult, however, that the kidneys played this rôle. Indeed, as already indicated, it is not improbable that they owe their importance to the fact that their position led to the belief that they are a central organ governing particularly the sexual functions. That this is the case is corroborated by the fact that, in the further development of these ideas of a corporeal soul, the kidneys more and more became secondary to the external sexual organs, and that the latter long continued to retain the dominant importance. Thus, the _phallus cult_, which was prevalent in numerous Oriental countries and which penetrated from these into the Greek and Roman worlds, may doubtless be regarded as the last, as well as the most permanent, expression of those ideas of a central corporeal soul that were originally associated with the kidneys and their surrounding parts. At the outset, the representation of the phallus was held to be not a mere symbol, as it were, but the very vehicle of masculine power. As a productive, creative potency, it was regarded as very especially characteristic of the deity, and, just as the attributes of deities were supposed to be vested in their images, so also was this divine power thought to be communicated to the phallus. In addition to and anteceding these ideas relating to gods, the phallus was held to be the perfect embodiment of demons, particularly of field-demons, who cause the ripening and growth of the seed. The belief in phallus-bearing demons of fertility probably dates back to the totemic age. The cults, however, to which such ideas of the corporeal soul gave rise, reached their mature development only in the following period. It was then that deity belief was elaborated, and it was in connection with the latter that the phallus became a universal magic symbol of creative power. With the decline of these cults, the symbol, according to a law observable in the case of other phenomena also, was again relegated, for the most part, to the more restricted field of its origin.