WALTER SLEZAK once saved my sanity over the course of a year, a long time ago, and I have never forgotten it. I never met him, but his death grieves me as though I had.

He was a B-plus actor in a world that settles for no less than A's in its entertainers, but he was certainly an A-plus person. He was a classical wit--cultured, knowledgeable, ironic, with the natural timing of a tightrope walker.

Where did I learn this? On daytime TV.

Back during my firstborn's colicky infancy, when he and I were pretty much trapped at home together, I discovered something called the "Jack Paar Show," which came on at midday. Heaven (and I suppose a long-gone network executive) only knows how it got there or why, but there it was, a shining little jewel of sophistication and intelligence stuck in between the giant giveaway shows--in vogue at that time--and the soaps.

Walter Slezak was what really gave that show its depth. He was a "guest," but appeared with great regularity. He got off double, triple, quadruple entendres that would be bawdy even on today's "Saturday Night Live," but day after day they went unchallenged--clearly not understood--by Victorian censors of less wit than stuffiness.

He seemed always to be saying "look at us--you out there who get this joke, and me--we really put one over on them this time, didn't we? . . ." I never presumed to think I was the only one "out there," but I have to say I never met anyone else who even remembers the show. Between bottles and formula and asthma attacks and not being able to drive, that little daily shot of dry wit did a lot to keep me going until the life style could be slightly revised.

Not too many people remember Slezak. Or that his father, the opera star Leo Slezak, was the Lohengrin who, when the Swanboat once was pulled offstage too soon, turned to the Metropolitan Opera audience and asked, "When does the next swan leave?"

(It was always a delight to me--like encountering an old friend--when Walter Slezak would turn up on the Met's Saturday Matinee entr'acte features like Opera Quiz.)

And how many know that there is still a Slezak on daytime TV--Erica Slezak, his daughter, as the long-suffering heroine Vicki, on the ABC soap "One Life to Live."

Walter Slezak wasn't the kind of actor who attracted fans who wrote fan letters. Nor was I the kind of fan who wrote them.

Now, I think, I'm sorry I didn't.