Tonight is David Letterman's final "Late Show." Although, as with his mentor Johnny Carson, last night's penultimate show was the real last one, with the return of Bill Murray and a musical performance by Bob Dylan, while tonight's will be largely clips and remembrances by Dave and Paul Shaffer.

I've never been much of a late-night talk show fan in general, though Letterman was my preferred option (both at NBC and CBS) when I did find myself in the mood to watch one. So I won't try to contrive a What David Letterman Meant To Me piece, especially since our Kris Tapley — a Letterman fan of long standing — has written a genuine and lovely version of that for you to read.

Instead, I wanted to pay tribute to what is simultaneously the quintessential Letterman moment and the one that's the antithesis of the Letterman persona: his remarks about 9/11 in his first show back after the Twin Towers fell.

This was Dave at his most sincere and heartfelt, speaking candidly and with great vulnerability on behalf of his adopted city and the pain it was going through. It was the exact right note that the show and the city needed from him, and I get choked up just thinking about it. (I have not had the nerve this morning to actually watch the clip of it that I've embedded below.)

Though Dave idolized Johnny, he wasn't built to be a great uniter of the audience in the way that Carson was. His sense of humor was too idiosyncratic, his persona too ironic, for him to be that guy on a regular basis whom the whole country wanted to hear from before they went to bed. (He also ascended to the 11:30 timeslot just as the audience was beginning to fracture to the point where even a young Carson would have had a hard time being that guy.) But on that night — and on a few others, like his emotional return from heart surgery — Letterman was absolutely that guy. His greater legacy will be in the influence his brand of comedy had in the generations who grew up watching him, and who now dominate the comedy ranks in both TV and film. But if we're talking about the larger history of television, the Letterman moment that will go in the time capsule (alongside Johnny's reaction to Ed Ames' errant tomahawk throw) won't be Dave throwing watermelons off the 30 Rock roof, or wearing the Alka-Seltzer suit, or tearing Paris Hilton to shreds. It'll be this:

As it should be. Thanks for that, Dave. We really needed it.

Alan Sepinwall has been reviewing television since the mid-'90s, first for Tony Soprano's hometown paper, The Star-Ledger, and now for HitFix. His new book, "TV (The Book)" about the 100 greatest shows of all time, is available now. He can be reached at