If a frog can dream, a frog can mourn.

Kermit T. Frog, who is Robin Hood to the very merry men that are the Muppets, resurfaces after a long absence tonight to join that old gang of his for a tribute to their founder and former boss. "The Muppets Celebrate Jim Henson," a captivating CBS special, airs at 8 on Channel 9.

Henson died unexpectedly in May, and since he had always been the voice and personality of Kermit, his alter-ego, it was widely feared Kermit would vanish from the public eye. His return tonight is tentative. At the opening of the show, it's stated that Kermy is traveling, and by postcard he informs his distinguished colleagues, "I'm fine, and will be back with you soon."

Much later, he appears in the wings as the Muppets sing their finale. That should have been that, really -- Kermit quietly leaving the theater after paying silent respects. But the producers unwisely decided Kermit should speak, too, using the voice of an actor not identified in the credits.

"His name is not being released at this time," a spokesman for Henson Associates said from New York yesterday, because he may not turn out to be the performer who assumes the role permanently.

What we are perhaps really hearing out of Kermit's flannel mouth is the cold hard voice of commerce. The Walt Disney Co. is still negotiating to purchase the Henson characters (Disney number crunchers, notoriously coldblooded, began dickering the price down after Henson's death) and the corporation has a financial interest in keeping a living Kermit part of the package.

To be fair, Henson's widow, Jane, was quoted yesterday as saying Jim would have wanted Kermit to remain with the troupe. "Kermit won't come back so strong at first," she told an interviewer. "Then, little by little, he will get his whole personality back."

Well, okay ...

Such ado about the emotional health of a manufactured amphibian! But as the special tonight makes clear for the umpty-umpth time, the Muppets have earned a prominent place in American popular culture and, indeed, in the heart of the world. Letters from children written at the time of Henson's death testify to that. One little boy drew a frog under a rainbow and wrote in crayon, "We will miss you, Jim Henson."

For the most part, tonight's is an extremely antic memorial service, set backstage at the Muppet theater, with lots of clips from productions of the past, guest-star visits by Carol Burnett, John Denver, Ray Charles and Harry Belafonte, and a quick history of Henson's television career, back to the Wilkins coffee commercials he did in Washington decades ago.

Gushy memorializing is kept to a bare minimum. Frank Oz, who started as a Muppeteer and is now a Hollywood film director, calls Henson "a man who truly believed nothing was impossible." What's impressive is not only the imagination and inventiveness that went into Henson's art, but the fact that he was always striving to take it to another level, sometimes with great success, always with great devotion.

Included among the non-Muppet clips are scenes from one of Henson's most accomplished and artful television productions ever, the eight brilliant "Storyteller" specials he did for NBC (a ninth has yet to air). These deserve to be repeated in their entireties.

Some of the monsters Henson created for movies like "Dark Crystal" and "Labyrinth" may frighten little kids tonight, but then this is a special that children and their parents ought to watch together anyway.

Herewith another warning: In the last act, the Muppets confront the fact that their mentor and friend and guardian is no longer alive and that they will have to go on without him.

It isn't going to be easy for them.

It isn't going to be easy for any of us.