Lewis Black tells Stephen Colbert why he's so angry: 'I wake up optimistic -- then I read the paper'
Lewis Black and Stephen Colbert (YouTube)

Stephen Colbert asked Lewis Black how he had remained bitter all these years.

The "Late Show" host said he'd met Black in 1997, when they both worked for "The Daily Show," and he'd been enraged the entire time.

"How do you keep the rage fresh?" Colbert asked.

Black said he didn't want to be angry and bitter, but it just happened naturally.

"I wake up in the morning, I'm severely optimistic -- more than anybody could imagine -- I believe that today is going to be the day that America figures it all out," Black said. "I'm convinced of it. We've made every mistake humanly possible, haven't we? So today, just by accident, we might stumble onto the answer. And then I pick up the paper and go, 'Son of a bitch!'"

Colbert showed Black a series of photos he'd found of him flipping his middle finger at the camera -- including at his own book signing, on a lovely spring day and after he'd won a Grammy Award.

"Nothing makes you happy," Colbert said. "If winning a Grammy doesn't make you happy, what will?"

Black said it made other people happy when he flipped them off, saying fans constantly ask him to do it whenever they saw him -- and Colbert asked if that ever made him angry.

"It just makes me wonder, I went to the Yale School of Drama for this?" Black said.

Watch the entire segment posted online by The Late Show With Stephen Colbert: