So often the man with the questions, Letterman has been subject to a few recently, as he stepped onto the other side of the desk as a recent guest of Jimmy Kimmel's, and an upcoming guest of Oprah Winfrey's. However this time was the turn of Charlie Rose on CBS' This Morning to get to know the chat-show goliath. 

Choosing candour, Letterman talked about his battle with depression, saying, "[I was] always quite skeptical about it. My friend and doctor, Louis Aronne, 20 years ago, he said, 'You should take something for this,' and I said no, because I thought it would make me loopy or make me hallucinate or make me drowsy, and he said, 'I'm telling you, just try a 10 milligram [dose]." As is so often the case, a concoction of standard-issue drugs can have an adverse effect on one's mental health, and that's exactly what happened to Letterman. "So I had the shingles really bad," he explained, "and part of the concoction of drugs they give you to fight that pain are pretty serious, and I just got tired of taking them," Letterman continued. "So I stopped taking them.

"And then I was really screwed," Letterman said. "So that's when I said to Louis, 'OK, OK, I'll try anything just to get rid of this depression.' Because it's different than, 'Oh, I don't feel good today.' It's different than feeling sad. It's different than feeling blue. It's really, like a friend of mine says, it's the world with 20/20 vision."

Letterman continues to talk about his experience as a father, in an openly honest interview. We guess, if you've been on the other side of the questions, you know what makes a good guest, and Letterman delivers on both fronts.