Twenty-five years ago this week, I wrote my first column. I'm not much given to self-reflection — why do you think I quit psychiatry? — but I figure once every quarter-century is not excessive.

When Editorial Page Editor Meg Greenfield approached me to do a column for The Washington Post, I was somewhat daunted. The norm in those days was to write two or three a week, hence the old joke that being a columnist is like being married to a nymphomaniac — as soon as you're done, you've got to do it again.

So I proposed once a week. First, I explained, because I was enjoying the leisurely life of a magazine writer and, with a child on the way, I was looking forward to fatherhood. Second, because I don't have two ideas a week; I barely have one (as many of my critics no doubt agree).

The first objection she dismissed as mere sloth (Meg was always a good judge of character). The second reason she bought. On Dec. 14, 1984, my first column appeared.

Longevity for a columnist is a simple proposition: Once you start, you don't stop. You do it until you die or can no longer put a sentence together. It has always been my intention to die at my desk, although my most cherished ambition is to outlive the estate tax.

Looking back on the quarter-century, the most remarkable period, strangely enough, was the '90s. They began on Dec. 26, 1991 (just as the '60s, as many have observed, ended with Nixon's resignation on Aug. 9, 1974) with a deliverance of biblical proportions — the disappearance of the Soviet Union. It marked the end of 60 years of existential conflict, the collapse of a deeply evil empire, and the death of one of the most perverse political ideas in history. This miracle, in major part wrought by Ronald Reagan, bequeathed the ultimate peace dividend: a golden age of the most profound peace and prosperity.

"I recently told an assembly at my son's high school," I wrote in 1997, "that they were living through a time so blessed they would tell their grandchildren about it. They looked at me uncomprehendingly ... because it is hard for anyone to apprehend the sheer felicity of one's own time until it is gone."

I concluded with "golden ages never last." Throughout the decade, and most especially as it began to wane, I returned to this theme of the wondrous oddity, the sheer impossibility of an age of such post-historical tranquility.

And inevitable ennui. So profound was that tranquility, so trivial the history of that time, that George Will and I would muse that if this kept up — an era whose dominant issue was a president's zipper problem — he might as well go back to the academy and I to psychiatry.

Of course, it didn't keep up. It never does. History is tragic, not redemptive. Our holiday from history ended in fire, giving birth to a post-9/11 decade of turbulence and disorientation as we were faced with the unexpected resurgence of radical eschatological evil.

Which brings us to the age of Obama, perhaps — mirabile dictu — the most exhilarating time of all. There is nothing as bracing for democracy as the alternation of power, particularly when it yields as serious, determined and challenging an ideological agenda as Barack Obama's. This third wave of transformative liberalism — FDR, then LBJ, now Obama — is no time for triangulation. This is not incrementalism. We're not debating school uniforms. When Obama once declared Ronald Reagan historically consequential and Bill Clinton not, he meant it. Obama intends to be the Reagan of the new liberalism.

It's no secret that I oppose nearly everything Obama has proposed. But after the enervating '90s and the tragic 2000s, the prospect of combative and clarifying 2010s, of sharply defined and radically opposed visions, is both politically and intellectually invigorating.

For which I'm tanned, rested and ready. And grateful. To be doing every day what you enjoy doing is rare. Rarer still is to be doing what you were meant to do, particularly if you got there by sheer serendipity. Until near 30, I'd fully expected to spend my life as a doctor. My present life was never planned or even imagined. An intern at The New Republic once asked me how to become a nationally syndicated columnist. "Well," I replied, "first you go to medical school. ..."