Last night, David Letterman spent some time remembering his dear friend, Robin Williams, who died a week ago. Letterman reminisced about his early days as a struggling comic, working at the famous Comedy Store in L.A. with Jay Leno, Elayne Boosler and Jimmie Walker in the 1970s when they first encountered this new guy who was supposedly from Scotland.

Letterman revealed that they weren't worried about Williams because he'd just talk about haggis, but when he performed, "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 have to put an end to show business. What can happen after this?' We get to see this night after night after night... We didn't approach him because we were afraid of him… we were thinking, 'Holy crap, there goes my chance at show business' because of this guy from Scotland."

Then Williams got plucked to star on Happy Days and Mork and Mindy. And being a generous guy, Williams got Letterman a guest role on the show.

The talk show host said that Williams had been on the Late Show on CBS and Late Night on NBC nearly 50 times: "It wasn’t until then that I sort of got to really know Robin Williams. He would come on to promote movies, or concerts, or whatever he was talking about, and he was always so gracious and we would talk about the old times. It was just a pleasure to know the guy. He was a gentleman and delightful."

After showing clips of Williams on the show—including one of him wearing doctor's scrubs, right after Letterman had his heart surgery—Letterman said, "Beyond being a very talented man, and a good friend, and a gentleman, I’m sorry, like everybody else, I had no idea that the man was in pain, that the man was suffering. What a guy, Robin Williams."

Here's an early clip of Williams and Letterman on the NBC show—they talk about Oprah: