Seven Things I Learned About David Letterman from Jason Zinoman's "Letterman: The Last Giant of Late Night."

Letterman felt that it was important to have guests who annoy the public because “it feels good to scream at the TV once in a while.”

Letterman thought that Ross Limbaugh was “very entertaining and also full of shit.”  

Before each episode of “Late Night,” Letterman snacked on pineapple and Hershey bars, carefully broken into small squares. (The chocolate was shipped to him directly from Hershey headquarters in Pennsylvania.)

Richard Nixon once asked his special counsel, Chuck Colson, about talk show host Dick Cavett, “is there any way we can screw him?”

Letterman was a “committed hypochondriac” with, among other supposed ailments,  a  “fragile” neck. He occasionally wore a neck brace. Everyone on the “Late Night” staff knew never to touch his neck.

According to longtime writer Steve Young, Letterman “was never truly comfortable unless he was seething with unhappiness at something.”

Johnny Carson preferred Letterman to Leno. After he left “The Tonight Show,” Carson periodically sent Letterman jokes for his show.

(Roz Warren is the author of Just Another Day At Your Local Public Library.)