Legendary funny man Robert Klein has a lot to laugh about these days. Jerry Seinfeld calls him nothing less than “the funniest, most intelligent, coolest comedian”; he’s just penned a new memoir, “The Amorous Busboy of Decatur Avenue” (Touchstone); and there’s a revival in Klein interest with the new DVD retrospective “Robert Klein: The HBO Specials 1975-2005” (Standing Room Only, $39.99). The collection packs eight HBO comedy shows onto four discs.

But in Klein’s mind, it’s a short hop, skip and jump back in time and across half a continent to Chicago in March 1965.

“It’s where everything started for me,” says Klein, who considers reporting for work at Second City “the first day of my career.” Back then, Klein made $150 a week and made fast friends with another rookie named Fred Willard – who would also go on to big things in the comedy realm.

“I drove my old Ford out to Chicago and got an apartment on Sedgwick Street, which is now a high-rise, and the Second City experience was fantastic,” Klein recalls. “I had to do a set show, and at the end was improvisation, and every memory was wonderful. I had a slow social start – and then I met a lot of girls. I went with a cellist from the Chicago Symphony Orchestra and was introduced to chamber music; I met interesting, creative people like (Second City pioneers) Sheldon Patinkin and Paul Sills. And I don’t think a year goes by when I don’t wind up back in Chicago.

“Especially now – it’s about time the Cubs won something.”

The reminiscence is pure Klein: sharp, observational, detailed and sealed with a kick. The man who turned the improvised blues wail “I Can’t Stop My Leg” into a staple of his act has come a long way. Klein made more than 80 appearances on Johnny Carson’s “Tonight” show and has a still-active acting career.

Then there are the HBO specials, which Klein delights in discussing. “All in all it’s a nice package, and HBO never, ever interfered creatively. I had so much creative freedom, and the only other experience I’ve had like that in my realm is my (memoir).”

Count Klein among those comedians who descended from the Lenny Bruce school, open to free association and game to tackle almost anything. His musings might seem tame in today’s world of “South Park,” “The Aristocrats” and a newly blue Bob Saget gone gonzo. But Klein has no regrets looking back at his old oeuvre.

“I am proud of the body of work,” he says. “It’s terrific, it’s tasteful, though I’m not a prude. There are a few (curse) words in there.” He still counts Bruce among his heroes and credits him with influencing his cable TV routines: “He was Christ-like, the sacrifice he made. Looking back, he was elegant; he was trying.”

As for today’s comics, the quick-thinking Klein isn’t so impressed. He says that though some stand-ups are fast on their feet, they rely too much on lewd language and shock value.

“On ‘New Joke City,’ I presented 50 new comedians, and every one of them got the job done, but not one of them was original – it was Alan King redux, Robert Klein redux, with a bit more profanity thrown in. Some of it is so dark – and I don’t see anyone reaching. … America has dumbed down to a certain degree. Computers are wonderful things and useful, but people are losing the heft of a book in their hands, and a well-lit place to read it. Everything is videos and action coming at you.”