To this theory it may naturally be objected that the divine consort of Jupiter was not Diana but Juno, and that if Diana had a mate at all he might be expected to bear the name not of Jupiter, but of Dianus or Janus, the latter of these forms being merely a corruption of the former. All this is true, but the objection may be parried by observing that the two pairs of deities, Jupiter and Juno on the one side, and Dianus and Diana, or Janus and Jana, on the other side, are merely duplicates of each other, their names and their functions being in substance and origin identical. With regard to their names, all four of them come from the same Aryan root _DI,_ meaning "bright," which occurs in the names of the corresponding Greek deities, Zeus and his old female consort Dione. In regard to their functions, Juno and Diana were both goddesses of fecundity and childbirth, and both were sooner or later identified with the moon. As to the true nature and functions of Janus the ancients themselves were puzzled; and where they hesitated, it is not for us confidently to decide. But the view mentioned by Varro that Janus was the god of the sky is supported not only by the etymological identity of his name with that of the sky-god Jupiter, but also by the relation in which he appears to have stood to Jupiter's two mates, Juno and Juturna. For the epithet Junonian bestowed on Janus points to a marriage union between the two deities; and according to one account Janus was the husband of the water-nymph Juturna, who according to others was beloved by Jupiter. Moreover, Janus, like Jove, was regularly invoked, and commonly spoken of under the title of Father. Indeed, he was identified with Jupiter not merely by the logic of the learned St. Augustine, but by the piety of a pagan worshipper who dedicated an offering to Jupiter Dianus. A trace of his relation to the oak may be found in the oakwoods of the Janiculum, the hill on the right bank of the Tiber, where Janus is said to have reigned as a king in the remotest ages of Italian history.