Of all the gods worshiped by the Romans, few are as interesting – both in appearance and in purpose – as Janus, the god from which we derive the name of the month January. Janus was unique to the Romans, and no parallel can be found in the religion of the ancient Greeks. He had several functions, but his most important was as the god responsible for beginnings of new enterprises – hence the reason for the adoption of his name for the first month of the year. Because of his ‘Janiform’ head (two heads conjoined at the back); he is also associated with the wisdom of surveying both the past and the future simultaneously.
During the Roman Republic when the coin was struck, Janus appears as the standard god on the front of bronze coinage, although only occasionally on silver coins. When the Roman Empire was created in 27 BC, he was seldom shown on coins. His temple in Rome was of great importance, and when it’s doors were open, the empire was at war somewhere, whereas on rare occasion when peace reigned, the doors were closed.