David Letterman was on hiatus last week when news of Robin Williams' apparent suicide broke - and he used his first show back to pay touching tribute to the late actor and comedian.

As has been noted in the days since his passing, Williams was one of the greatest of all talk show guests, and he appeared on "Letterman" a whopping 50 times - a legacy memorialized in a loving video tribute made up of clips from Williams' various appearances on the show. Letterman also talks about seeing him on stage for the first time as a young comedian at the Comedy Store in Los Angeles:

"It's like nothing we had ever seen before, nothing we had ever imagined before," Letterman describes. "This guy comes in, and we're like morning dew, he comes in like a hurricane. And now, the longer he was on stage, the worse we feel about ourselves because it's not stopping. And then he finishes, and I thought, 'oh, that's it, they're gonna have to put an end to showbusiness, because what can happen after this?'"

I think the most poignant and piercing moment comes at the end, when Letterman sums up his bewilderment over the tragic loss thusly: "I had no idea that the man was in pain, that the man was suffering."

You can check out the full segment below.

A former contributor to sites including MTV's The Backlot and Bloody-Disgusting, Chris Eggertsen worked in film development before indulging his love of pop culture writing full time. He specializes in horror, the intersection of social issues and entertainment and Howard Stern. He's on Twitter @HitFixChris.