IT IS ALWAYS a cliche, most always a lie, to say that a director has somehow emancipated a play by taking liberties. So I won't say that, not exactly. What Timothy Mayer has done for The Bacchae is put it out of harmony with the stage conventions according to which it was written. He has emancipated it only from a narrow theatrical orthodoxy which insists on treating all plays of a given place and period alike, whose loyalty is to a set of rules empirically drawn from history rather than to the will of an author as unfolded in his work. Above and beyond this considerable accomplishment, Mayer's modern-dress treatment of Euripedes' classic is all-told the most intoxicating thing launched these last few years on a Boston stage.

An uncritical director could, I guess, go too far excavating hints of one writer's insurrection against contemporary dogma. But in Euripedes the hints are powerful, and the greater danger probably that of underinterpretation. There is no avoiding, for example, his irregular attitude toward the divinity, which seems to have ranged from outright negation to the most grudging and unsettling sort of affirmation. In The Bacchae, the gods are gods indeed, but their order is--besides whimsical--cruel and misguided. And Mayer's willingness to portray Dionysus as an effeminate, self-absorbed individual, worthy of nearly every label the unbelieving Pentheus attaches to him, brings this side of Euripedes out into the open. The modern costumes, particularly the policemen's garbs in which Pentheus's men are clothed, suggest the further metaphor of entrapment: Dionysus himself seems to have unleashed the chain of events leading to Pentheus' death.

KEVIN O'CONNOR blends as smoothly into Mayer's conception of Dionysus as the conception does into the play. And as Pentheus, Leon Russom is the perfect physical contrast to O'Connor, while at the same time an exceptionally able and disciplined actor. In his characterization, however, lies a failure of definition that badly undercuts the action of the play. Pentheus must metamorphosize somewhere along the line from a hyper-rationalist into a pathetic, obsessed figure; and Russom, or Mayer, has chosen the wrong moment for the metamorphosis. When Pentheus emerges from the ruins of his palace, razed to the ground by Dionysus, he should be a changed man, brought low like his palace and therefore susceptible to the god's vengeance. But as Mayer has staged it, the real change is postponed to the intermission, and Pentheus agrees to Dionysus's offer only out of intense curiosity. As a result, when Pentheus finally does go mad, a scene Russom overplays a little, the effect is unconvincing.

The remaining flaws of this production are minor, and exclusively on the side of execution rather than conception. The chorus blocking, for instance, still needs work, as do several of the long speeches, but one has every right to expect these problems will soon be corrected.

One has every right because Mayer has assembled a truly magnificent little cast, distinguished by an incredible variety of voices. Foremost among the voices is that of Yolande Bevan, who lifts the chorus to her own extraordinary level, but not much less distinctive are the speaking styles of Edward Finnegan and Donald Marye, as Cadmus and Teiresias. The best performance of the lot, however, has to be that by Patricia Cutts, who bravely circumvents the sort of theatrics to be expected in a woman who has killed her son and partaken of his remains.

Separating Richard W. Kerry's set from Mayer's use of it would be an impossible feat. Suffice to say the union speaks extraordinarily well for both parties.