Amid the rising din of millennium-inspired commentary, a single remark floated free recently, then fluttered down to lodge quietly in the mind. It didn't come from a pundit looking to say something portentous. It came from the British pop-music composer turned classicist Joe Jackson, introducing his brand-new, evidently unconventional "Symphony No. 1" with the sensible remark that "on the eve of the 21st century, a piece that is symphonic in structure doesn't have to be written for a 19th-century orchestra to qualify as a symphony."

Mr. Jackson touched unwittingly here on the sensation everyone experiences faintly at the turning of a year, more strongly at the turn of a decade and overwhelmingly -- we imagine -- at the turn of a century, never mind a millennium: the sense of things falling into place, the feeling of having finished something and moved beyond it. It could be compared to the feeling one gets closing, successively, a page, a chapter, a book and a series (although a better metaphor for the end of the millennium might be walking out of the library, shutting the door and heading for the cybercafe).

With each act of closure, what before had loomed large enough to fill one's whole mental horizon retreats and diminishes, ranked by context. The mountain that blocked out the sky is suddenly just part of a range extending infinitely backward. What had seemed a given becomes an option -- like 19th-century orchestral styles or print media. What had seemed a bedrock part of the human condition -- the Great Chain of Being, the British Empire, the Emperor system -- is worn down by the flow of years until it is nothing but a quaint relic, a handful of splendid dust. Call it perspective or simply a sense of history, it is brought into focus whenever we celebrate one of these utterly artificial markers in the river of time. And now the biggest marker in a thousand years is just around the bend.