LOS ANGELES - "Fifty years!" Bob Newhart marveled. "It's like where the hell did the time go?"

The comedian was ruminating recently as he relaxed between concert dates on a 14-city tour celebrating his golden anniversary in show business.

"I'll tell you how the world has changed," he said in the living room of his secluded Bel-Air home. "We were all called the sick comics. Time magazine did an article on all of us: Lenny Bruce, myself, Shelley Berman and Mike Nichols and Elaine May. Lenny was knocking over all kinds of sacred topics, and we all were called 'sick.' I was making people sick because I made fun of a president - Abe Lincoln. Compared to today, it's hard to believe."

Newhart's very first gig was at a night club in Houston. His act went north - but downhill - from there.

"I was in Windsor, Canada, and I died every night," Newhart recalled. "Not a snicker, not a laugh. I almost went back to accounting (his previous endeavor). I told myself, 'That's it.' Then I played Winnipeg, and it was fine. But there isn't a standup comedian who hasn't had just one but a bunch of bad performances."

Two weeks after his debut in Houston, he recorded "The Button-Down Mind of Bob Newhart." ''It then went crazy and went beyond anyone's expectations, especially mine."

At 81, Bob Newhart has reached the age when many performers call it quits.

"I've had time off and it drove me nuts," he claimed. "I was crawling up the wall.

"I know some people who say, 'I wanna quit making people laugh. I'm tired of making people laugh.' That doesn't make sense to me. Why would I want to stop doing it? When you do a show and it works and you come off stage and they've had a good time and you've had a good time. Why stop doing that?"

He explained his modus operandi: "I have an idea and I'll try it in Seattle and maybe refine it a little more in Calgary and refine it a little more in Vancouver. The art of it is doing it 10 million times and see what happens. That's a kick. The art of doing it 10 million times but make it seem like the first time. That's the art of it.

"About 6 p.m., I start pacing up and down getting ready for the show. You never take it for granted but when you do it will slap you in the face and make you wake up."

He was asked if he ever lost his place during a performance.

"Oh yeah," he responded. "In Las Vegas one time I was doing two shows a night, seven days a week. You start telling a joke, and it wasn't getting the reaction that I thought it usually did. I'd do it again and they're all starring at me and saying 'Why is he telling this joke again?'"

"I don't have any health problems," he commented, "but flying is a pain in the ass: lost luggage, canceled flights. But once you are there, it's easy."