The tradition of the New Year's Resolutions goes all the way back to 153 B.C. Janus, a mythical king of early Rome was placed at the head of the calendar.
With two faces, Janus could look back on past events and forward to the future. Janus became the ancient symbol for resolutions and many Romans looked for forgiveness from their enemies and also exchanged gifts before the beginning of each year.
The New Year has not always begun on January 1, and it doesn't begin on that date everywhere today. It begins on that date only for cultures that use a 365-day solar calendar. January 1 became the beginning of the New Year in 46 B.C., when Julius Caesar developed a calendar that would more accurately reflect the seasons than previous calendars had.
The Romans named the first month of the year after Janus, the god of beginnings and the guardian of doors and entrances. He was always depicted with two faces, one on the front of his head and one on the back. Thus he could look backward and forward at the same time. At midnight on December 31, the Romans imagined Janus looking back at the old year and forward to the new. The Romans began a tradition of exchanging gifts on New Year's Eve by giving one another branches from sacred trees for good fortune. Later, nuts or coins imprinted with the god Janus became more common New Year's gifts.
In the Middle Ages, Christians changed New Year's Day to December 25, the birth of Jesus. Then they changed it to March 25, a holiday called the Annunciation. In the sixteenth century, Pope Gregory XIII revised the Julian calendar, and the celebration of the New Year was returned to January 1.
The Julian and Gregorian calendars are solar calendars. Some cultures have lunar calendars, however. A year in a lunar calendar is less than 365 days because the months are based on the phases of the moon. The Chinese use a lunar calendar. Their new year begins at the time of the first full moon (over the Far East) after the sun enters Aquarius- sometime between January 19 and February 21.
Although the date for New Year's Day is not the same in every culture, it is always a time for celebration and for customs to ensure good luck in the coming year.
courtesy of Goals Guy, Painting, A Dance to the Music of Time by Nicholas Poussin