"This is a show of substance and significance," comedian Jackie Mason said during his one-night stand at Strathmore Hall on Saturday night.

And he was right. His one-man show dealt with such substantive topics as Judaic studies, comparative religion, Shakespeare's plays, gay marriage, the legal travails of Martha Stewart and why plumbers are more important than actors.

But of course Mason returned over and over again to the anthropological topic that has obsessed him throughout his 40 years in showbiz -- the differences between Jews and gentiles.

"With one question I can tell if you're a Jew or not: Do you know your cholesterol number?" the rabbi-turned-comic said. "Every gentile knows the football scores. Every Jew knows his cholesterol number."

Jews are obsessed with their health because they're always sick -- or at least tired, Mason said. That's because Jews have trouble sleeping. "Gentiles sleep like a dead horse," he said. "Homeless gentiles sleep in the street. A Jew has a $9 million condo and he can't sleep."

But the great thing about gentiles is that they're so easy to entertain. "Gentiles enjoy everything," Mason said. "They even enjoy Niagara Falls -- water falling down, they can't get over it."

Not only that, but gentiles go ga-ga over the Grand Canyon. "The Grand Canyon -- it's a hole! That's it! Jews see a hole in the ground, they only ask one question -- You think we can sue these bastards?"

Of course, Mason's monologue was not just a dry anthropological lecture. He also weighed in on the pressing issues of the day -- such as President Bush's propensity for mangling the English language. The ability to speak glibly is not a reliable indicator of intelligence, he said: "Who's a better speaker -- a used car salesman or a scientist?"

Unlike Bush, Mason came out strongly in favor of gay marriage: "It's just an alternative lifestyle." He also came out in favor of marriage between men and horses: "It's not my business unless it's my horse. And then there's only one valid question: Is the horse happy or not?" (Do these jokes work on paper? Maybe not. But when he gets rolling onstage, he's as funny as anybody.)

Mason ambled around the stage and rambled on for about an hour. Then he announced that there would be an intermission. "The Jews are hungry," he explained.

That announcement was important, particularly to me. Back in 1999, I attended Mason's show at the Kennedy Center. When the lights came on and he left the stage, I ran out of the theater, hustled back to The Post and wrote a review for the next day's paper, praising the show but griping that it was too short. The next day, dozens of helpful readers called in with constructive criticism: "You idiot! You left at intermission!" The Post ran a correction identifying me, by name, as a "schlemiel." My career has been floundering ever since.

So this time, I stayed for the whole show. And I'm glad I did because I got to hear Mason's learned textual analysis of several of Shakespeare's most famous lines: "My kingdom for a horse?" Mason said. "I could see giving up your kingdom for a couple of broads. But for a horse?"

I also got to hear Mason's convincing critique of putting Martha Stewart on house arrest: "What's the worse she could do -- sneak into your house and redecorate it?"

He also explained why it's silly to get all excited about which actor wins an Academy Award: "Who's more important -- a plumber or an actor?" he asked. "Did you ever hear anybody driving down the highway say, 'Get off at the next exit, I gotta go to the movies?' "

On and on he went, a voice kvetching in the wilderness. Mason is 74 now, and so are many of his jokes. But he's still funny. I laughed so hard that tears rolled down my chin.

But I'm a gentile -- and you know how easy they are to entertain. I even like Niagara Falls and the Grand Canyon. In fact, I like the Grand Canyon better than Jackie Mason. But Mason beats out Niagara Falls. Falling water is nice, but laughing till it hurts is even better.

Shtick-to-it-iveness: The former rabbi's riffs on the Jewish experience still produce tears of laughter after 40 years.