The Romans set January as the first month of the year. Originally, March had been the start of the new year. But the early Roman kings, before the republic, moved it to coincide with Janus, a two-faced god who looked backward with an old face and forward with a young face. Julius Caesar realigned Roman governance around January being the start of a new year of governance.
The reality, however, is it is arbitrary and we have all given great psychological importance to it. The pagans of Rome...