Diana's fellow, Divus Janus, was sometimes called Dianus, but much more commonly Janus, and from being merely the sun, he became allegorical of the entire year, and had a statue with four faces, for the seasons, and hands pointing the one to 300, the other to 55, thus making up the amount of days then given to the year; and before him were twelve altars, one for each month.  He thus presided over the beginning of everything, and the first month of the year was from him called Januarius, as were all gates jani, and doors januæ; and above all, that gate between the Sabines and the Romans, which was open when they were friends, shut when they were foes.  When the two nations had become thoroughly fused together, the gate grew to a temple; but the ceremony of shutting the doors was still followed on the rare occasions when Rome was at peace, and of opening them when at war to let the god go out, as it was now said, to help the Romans.  This idea of peace, however, turned Janus into a legendary peaceful monarch, who only wore two heads that he might look both ways to see either side of a question, and keys were put into his hand as the guardian of each man's gate.  His own special gate continued to be called Janicula, his name passed from the door, janua, to the porter, janitor; and then in modern times to St. Peter, who, bearing the keys, was called by the Italians, il Janitore di Cielo, and thence the fish, which was thought to bear the mark of St. Peter's thumb, was il janitore, or, as we call it, the John Dory, if not from its gilded scales, dorée or dorado.  Its Spanish name of San Pedro would favour the janitor theory... (History of Christian Names, Yonge, 1884).