The departure of David Letterman from the late night broadcast airwaves has generated much online comment and many nostalgia-driven puff pieces, and I’ll try not to add too much to that burgeoning heap. But a few points before the gap-toothed one rides off into the sunset: One, it’s easy to forget how big a deal Letterman’s move to CBS was, and how it was one of the bigger things to happen in television history — in a TV landscape where the big three networks were still the Big Three Networks. I mean, it was HUGE. Two, we should all thank Mr. Letterman for his contributions to the comic book medium, both his The Dark Knight Returns doppelganger, David Endocrine, and his Avengers-loving self. Three, twenty-two years sure goes fast. I don’t feel old, but I’m sure as hell not a teenager anymore, taping the first Late Show on my VCR. Time flies, folks.