'Selavy's Magic Theatre' careens uproariously across the stage

Dr. Selavy's Magic Theatre (C'est La Vie). Conceived and directed by Richard Foreman. Music by Stanley Silverman. Lyrics by Tom Hendry.

Revivals are rare in the more exploratory crannies of theater. Experimenters must keep experimenting, after all, or we might forget how forward-looking they are. Still, bygone productions are restaged now and then, letting us see if the wave of the future has stood the test of time.

It's especially pleasing to have ''Dr. Selavy's Magic Theatre'' back on the boards (at St. Clement's) since many adventurous playgoers regard it as a classic - though a classic of what, it's hard to pin down. Suffice to say it's a lively, slippery, uproarious show full of songs, dances, jokes, visions, and collapsing scenery, all held together by a score that swings from operatic recitative to 1950s doo-wop, with stops at all stations between.

Though the Stanley Silverman music and Tom Hendry lyrics are essential to it, the show is clearly a product of Richard Foreman's teeming talent, from the punning title (Selavy is pronounced ''c'est la vie'') to the shadowy plot about a ''patient's progress'' through a bizarre ''five-day cure'' in a mad doctor's madhouse.

Antic all the way, the action pits this brave character against pirates, business, and various temptations - his third day's ''treatment,'' for example, is ''Letting him dream of love, but warning that it probably won't last.'' I suppose he gets cured, because everyone puts on party hats near the end. But it hardly matters, since the lunatics obviously took over this asylum long before we arrived, and very entertaining lunatics they are.

As in much Foreman work (including such Silverman collaborations as ''Madame Adare'' and the spectacular ''Elephant Steps'') there's a dark side to every joke and a bright side to every tragedy that careens across the stage during the show's hour-plus running time. The wildly eclectic music accompanies a nonstop barrage of songs with titles like ''Bankrupt Blues'' and ''Doesn't It Bug You.'' For all the bizarre flourishes that surround them, most are sung tunefully and fetchingly by a near-ideal cast including such Foremania experts as Jessica Harper and Roy Brocksmith. The offstage instrumentalists, led by Michael Ward, give them vigorous support.

If this highly energized ''magic theater'' has a persistent flaw, it's one that often crops up in Foreman's productions: The action is so vividly and persistently strange that both the eye and the mind start pleading for relief well before the final curtain. But Foreman's relentless brilliance makes the trip more than worthwhile, to be sure, and the musical dimension of ''Dr. Selavy'' lightens the load with a good deal of outright sprightliness.

There's a disturbing undercurrent - and deliberately so, I think - to this restless entertainment. It's not quite the musical comedy it seems to be. It's somebody's dream of one, on an unquiet and unsettled night.