The sixth season of ''The Shakespeare Plays'' is upon us, and this milestone series encompassing William Shakespeare's 37 dramatic works is celebrating the event by bringing to television audiences what may be one of the theater's greatest versions of Macbeth. (PBS, tonight, 9-11:30 p.m., check local listings for premiere and repeats.)
It would be hard to imagine a more savage and driven, a more naive and self-deceived, a more conscience-stricken and nearly understandable, Macbeth than Nicol Williamson's. He grasps one of the most fascinating Shakespearean roles like a dog with a bone in his mouth, growls menacingly as he munches on it , then buries it in the literature of theater - to be remembered for all time.
No matter that he alternately underplays and overplays, that he sometimes mumbles and sometimes speeds up his speech so much that he is almost incomprehensible. What matters is the overall character he creates indelibly in the viewers' mind and heart. His Macbeth voices meaningful words; the focus is on character and plot rather than lofty theatrical Shakespearean intonation.
The same is not always true of Jane Lapotaire's Lady Macbeth. Too often she is reciting Shakespeare rather than acting Shakespeare, and in several instances her exaggerated acting style borders on the ludicrous. I had the impression of a ''Saturday Night Live'' takeoff of Macbeth rather than the real thing. Perhaps, though, it is asking a bit too much for any Lady Macbeth to match the superb standards of Williamson's Macbeth.
Produced by Shaun Sutton and directed by Jack Gold, this production often cannot make up its mind if it wants to be a studio-stylized version or a naturalistic version, just as sometimes its actors' styles conflict with each other. But director Gold almost always solves his dilemma with close-ups, close-ups, close-ups. That's something TV can offer audiences that the theater cannot. And Gold makes almost too much use of close-ups, often disdaining the long shot which would have revealed a bit more of the body language of Shakespeare, as distinct from the vocal language.
So, it is not a perfect ''Macbeth,'' but it is an unforgettable Macbeth.
I will not impose upon you once again the familiar plot of Macbeth, a story of ambition, terror, corruption . . . and guilt. But even today, in our society, if one looks closely one can find evidence of the same kind of blind ambition which drives political figures to misjudge their own powers.
''Macbeth,'' like the other plays in the Shakespeare folio, is a co-production of BBC-TV and Time-Life Television, presented on PBS by WNET/NY.
The underwriters are also providing funds for an enormous outreach program that provides free classroom materials for classroom use.
According to ''The Shakespeare Quarterly,'' the school program has been ''quietly altering the landscape of the secondary schools in the US.''
Nicol Williamson's ''Macbeth'' almost alone quietly alters the landscape of Shakespeare on American television.