New Year's Day is, in a way, a meta-holiday; it's a celebration of existence, of life, as such. That's why it can be seen as a taking stock of the past and a look to the future at once. The common theme here is one's own life: where one has been and where one wants to go. The holiday takes introspection and turns it outward in celebration.
The two main traditions that define the holiday, the singing of "Auld Lang Syne" and the establishment of New Year's resolutions, capture the backward and forward looking nature of New Year's Day. "Auld Lang Syne," a song everyone knows, yet almost no one knows the lyrics to, is concerned with fondly looking back. The title roughly translates to "days gone by."
Should old acquaintance be forgot,
and never brought to mind?
Should old acquaintance be forgot,
and days of old lang syne?
For auld lang syne, my dear,New Year's resolutions, on the other hand, are commitments to better oneself in the coming year. No matter how good or bad the prior year was, the tradition of making resolutions is still one of further improvement.
for auld lang syne,
we'll take a cup of kindness yet,
for auld lang syne.
There is a third tradition that unites both aspects of New Year's Day: the drinking of champagne. Champagne is traditionally brought out for the most important of celebrations, and it shows the import of the New Year's holiday. Here's where you raise a glass and toast; it's both a well done! and a here we go! in one clink of glass.
The underlying premise is that life is worth celebrating and is capable of being improved. It's a feeling few people express during the rest of the year. For some that feeling survives the afterglow of the holiday and is a permanent state of mind. But for a few hours before and after midnight on December 31, we can feel that life isn't only a series of disappointments and frustrations. For a few hours we can all agree on one thing: life is good.