Janus is the nominal divinity for the parts of the world that follow the Roman calendar and start their years with "January." With delinquencies in my Bulfinch and Hamilton noted, I say Janus was one Roman god who was not copied from some Greek precedent. If the scholars are right, he was formed before much of the Greek influence came. He evolved from the native Latin spirit of doorways, ianua.
As you may have read in the volumes or heard in homilies of the more classical-thinking priests, Janus was remarkable for his head. It had two faces, one looking forward, another looking back. He was a god of new beginnings, new years. He also presides over ends. As the deity of the doorway, he is the god of both entry and departure. His immortal eyes stare down both things to come and things past.
Down on the mortal, local, and more culturally significant plane, we have our very own saying about people who do not acknowledge their origins:
"Ang hindi lumingon sa pinanggalingan,
di makararating sa paroroonan."
Despite the resonance of this theme in our contemporary literature and even in popular culture products such as films, somehow the still mechanistic world-view tells us that we don't have to look back. Where to and where from are two distinct points in any map. Alpha is irrelevant and Omega is entirely up to you. No need to confuse the two.
Well, that is one way of looking at it. Nevertheless, someone can always stand up and dare say, despite all the points and lines, it's still just one map. It's just one door.
Whatever. Happy new year.