In ancient Roman mythology, Janus, a very old Italian deity, is the god of beginnings and transitions. Thus he is a gatekeeper deity, often seen depicted on doorways and entrances. Moreover, he is also shown with two heads – one looking forward (to the future) and one looking backwards (to the past). Not only is he a god of physical transitions but also of spiritual ones too. Also a god of rites of passage such as from youth to adulthood. In Roman religion he was worshipped at any event or situation that involved transition or change – births, deaths, marriages, harvest time etc. He is also seen as a god mediating between the states of barbarism and civilisation. As well as a god of transitions he is also seen as a solar deity.
As for Janus’s beginnings, one tradition says that he originally came from Thessaly and that he was welcomed by Camese into Latium, where they shared the kingdom. They were married and had several children, oner of whom was the river-god Tiberinus (after whom the River Tiber is named). After his wife died Janus became the sole ruler of Latium. He gave shelter to Saturn when he was fleeing from Jupiter. Janus provided peace and welfare for his people and after his death he was deified and became protector of Rome. The gates of his temple were always kept open during times of war so the god could intervene if necessary. During times of peace they were closed.
However, Janus may possibly go back much further in time than the ancient Romans. Various scholars have drawn similarities between Janus and the Indian Goddess Aditi and the Scandinavian God Heimdallr. Gods with two heads have also been found in Babylonian art and ancient Syro-Hittite.