’Tis the season to be jolly, but also the season for which an affective disorder is named — the winter blues known by the acronym SAD. December is the month of living intensely, when feelings run high and low, and moods swing from hurt to happiness. The period between Thanksgiving and New Year’s is generally understood in terms of particular religious and cultural observances. But the meaning of what we call “the holidays” goes deeper than any one tradition, as we humans plunge more fully into what makes us human in the first place.

Indeed, in December time itself moves to the center of our awareness. Humans swim in the flow of past, present, and future, but unlike fish, we know what we are swimming in — especially during these waning days of the year. Whether noting the date with the number 12, or compiling records for the accountant, or rushing to meet a deadline, we see the calendar winding down. This year in America, the so-called “fiscal cliff” makes the ticking of that clock louder than usual, but the approach of year’s end is always laden.