We’re now less than a month away from David Letterman’s final bow on The Late Show, an event which will end a career in late night television that’s spanned more than three decades. Everyone agrees that this is a momentous event, a paradigm shift in late night programming, but few are able to articulate it as well as Conan O'Brien.

Once upon a time, O'Brien was the guy who succeeded Letterman at NBC’s Late Night desk, and many comedy fans felt he was the obvious choice for Letterman’s Late Show replacement. Alas, Stephen Colbert ultimately won that job, and O'Brien will go on with his own late night show on TBS, but that doesn’t mean he can’t weight in on just how important Letterman was to late night comedy.

In a new essay for Entertainment Weekly, O'Brien laid out just how, and why, Letterman became so important to the world of late night comedy, and comedy at large. You should definitely go and read the whole thing, but here’s a particularly poignant segment.

“Dave’s show was that rare phenomenon: a big, fat show business hit that seemingly despised show business. Dave didn’t belong, and he had no interest in belonging. He amused himself, skewered clueless celebrity guests, and did strange, ironic comedic bits that no one had seen on television before. Everything about that show was surreal and off-kilter. Where late night television had once provided comfort, this man reveled in awkwardness. Cher called him an asshole. Andy Kaufman ran screaming from the set. Chris Elliot lived under the stairs. Throughout one episode the entire show rotated a complete 360 degrees, for no reason whatsoever. By 1985, when I graduated from college and was ready to try my hand as a comedy writer, Late Night with David Letterman had been the Holy Grail for several miraculous years.”

Letterman’s final episode of The Late Show will air on May 20, and it’s sure to be a TV event for the ages.