When the Persians had once yielded to the syncretic spirit so far as to unite the Magian tenets and practices with their primitive belief, they were naturally led on to adopt into their system such portions of the other religions, with which they were brought into close contact, as possessed an attraction for them.  Before the date of Herodotus they had borrowed from the Babylonians the worship of a Nature-Goddess, whom the Greeks identified at one time with Aphrodite, at another with Artemis, at another (probably) with Here, and had thus made a compromise with one of the grossest of the idolatries which, theoretically, they despised and detested.  The Babylonian Venus, called in the original dialect of her native country Nana, was taken into the Pantheon of the Persians, under the name of Nansea, Anaea, Anaitis, or Tanata, and became in a little while one of the principal objects of Persian worship.  At first idolatry, in the literal sense, was avoided; but Artaxerxes Mnemon, the conqueror of Cunaxa, an ardent devotee of the goddess, not content with the mutilated worship which he found established, resolved to show his zeal by introducing into all the chief cities of the Empire the image of his patroness.  At Susa, at Persepolis, at Babylon, at Ecbatana, at Damascus, at Sardis, at Bactra, images of Anaitis were set up by his authority for the adoration of worshippers.  It is to be feared that at this time, if not before, the lascivious rites were also adopted, which throughout the East constituted the chief attraction of the cult of Venus.

With the idolatry thus introduced, another came soon to be joined.  Mithra, so long an object of reverence, if not of actual worship, to the Zoroastrians, was in the reign of Artaxerxes Mnemon, honored, like Anaitis, with a statue, and advanced into the foremost rank of deities.  The exact form which the image took is uncertain; but probability is in favor of the well-known type of a human figure slaying a prostrate bull, which was to the Greeks and Romans the essential symbol of the Mithraic worship.  The intention of this oft-repeated group has been well explained by Hyde, who regards it as a representation of the Sun quitting the constellation of Taurus, the time when in the East his fructifying power is the greatest.  The specimens which we possess of this group belong to classical art and to times later than Alexander; but we can scarcely suppose the idea to have been Occidental.  The Western artists would naturally adopt the symbolism of those from whom they took the rites, merely modifying its expression in accordance with their own aesthetic notions.

Towards the close of the Empire two other gods emerged from the obscurity in which the lower deities of the Zoroastrian system were shrouded during the earlier and purer period.  Vohu-manu, or Bah-man, and Amerdat, or Amendat, two of the councillors of Ormazd, became the objects of a worship, which was clearly of an idolatrous character.  Shrines were built in their honor, and were frequented by companies of Magi, who chanted their incantations, and performed their rites of divination in these new edifices as willingly as in the old Fire-temples.  The image of Bah-man was of wood, and was borne in procession on certain occasions.