Pergamos itself became part and parcel of the Roman empire, when Attalus III, the last of its kings, at his death, left by will all his dominions to the Roman people, BC 133. For some time after the kingdom of Pergamos was merged in the Roman dominions, there was no one who could set himself openly and advisedly to lay claim to all the dignity inherent in the old title of the kings of Pergamos. The original powers even of the Roman Pontiffs seem to have been by that time abridged, but when Julius Caesar, who had previously been elected Pontifex Maximus, became also, as Emperor, the supreme civil ruler of the Romans, then, as head of the Roman state, and head of the Roman religion, all the powers and functions of the true legitimate Babylonian Pontiff were supremely vested in him, and he found himself in a position to assert these powers. Then he seems to have laid claim to the divine dignity of Attalus, as well as the kingdom that Attalus had bequeathed to the Romans, as centering in himself; for his well-known watchword, "Venus Genetrix," which meant that Venus was the mother of the Julian race, appears to have been intended to make him "The Son" of the great goddess, even as the "Bull-horned" Attalus had been regarded. *
* The deification of the emperors that continued in succession from the days of Divus Julius, or the "Deified Julius," can be traced to no cause so likely as their representing the "Bull-horned" Attalus both as Pontiff and Sovereign. Then, on certain occasions, in the exercise of his high pontifical office, he appeared of course in all the pomp of the Babylonian costume, as Belshazzar himself might have done, in robes of scarlet, with the crosier of Nimrod in his hand, wearing the mitre of Dagon and bearing the keys of Janus and Cybele. *
* That the key was one of the symbols used in the Mysteries, the reader will find on consulting TAYLOR'S Note on Orphic Hymn to Pluto, where that divinity is spoken of as "keeper of the keys." Now the Pontifex, as "Hierophant," was "arrayed in the habit and adorned with the symbols of the great Creator of the world, of whom in these Mysteries he was supposed to be the substitute." (MAURICE'S Antiquities) The Primeval or Creative god was mystically represented as Androgyne, as combining in his own person both sexes (Ibid.), being therefore both Janus and Cybele at the same time. In opening up the Mysteries, therefore, of this mysterious divinity, it was natural that the Pontifex should bear the key of both these divinities. Janus himself, however, as well as Pluto, was often represented with more than one key.