"Equus" must drive psychiatrists crazy. Let this be mistaken for a recommendation in some quarter, perhaps I should add that I mean reputable, conscientious pshchiatrists.

Charlatans may be inclined to feel flattered by the delusions of omnipotence that Peter Shaffer ascribes to the protaganist of his play, a child psychiatrist named Dr. Dysart, but this peculiarly addled, self-dramatizing shrink could provoke only dismary or contempt among self-critical members of the profession.

Confronted with the case of a stablebody, Alan Strang, who has driven a spike through the eyes of six horses, Dysart doesn't agonize over the questions that might be expected to preoccupy him - whether he can discover the source of the patient's distress and do something to heal it. On the contrary, he reaches alarmingly quick, presumptuos conclusions about the motive behind the patient's crime and then esoteric question of whether he has a right to intefere with a distrtssed mind.

I vaguely recall a "Ben Casey" episode in which the hero, a brain surgeon, entertained some legitimate doubts about now a needed operation would affect the mental processes of a visionary evangel st. Dysart seems to equate psychiatry with brain surgery. He convince himself that Alan was acting out of a religious ecstasy and feels envious because he can't fell spiritually inferior.

Dysart's confusion bothered many critics, but it never seemed to interfere with the play's theatrical appeal. Even reviewers who considered the text dubious tended to praise John Dexter's staging, in which actors in stylized costumes represented the horsed whom Dysart beleived Alan had come to worship as godlike figures.

It remains to be seen if the theatrical appeal will carry over to the movie version, opening today at the Avalon 1, because director Sidney Lumet's literal-minded approach appears to expose weaknesses obscured in the stage.

Shaffer has gone astray in the course of trying to justify Dysart's anguish, which seems essentially a reflection of the playwright's own desire to create something transcendantly stirring and revelatory. He hasn't succeeded, but his oratory is so agitated and his stagecraft so astutely contrived in certain respects that audiences may be forgiven for confusing aspiration and ostentation with dramatic substance. Shaffer may not have created at respectable work of art, but he certainly created a hit with delusions of grandeur.

Shaffer contrives to have his theatrical cake and eat it. A mystery melo-drama, the play involves audiences in the process of investigating and "cracking" a criminal case, in this instance the motives behind Alan's maiming of the horses. At the same time Shaffer expects us to take Dysart's torment seriously, to go along with his preposterous doubts about Alan's need for treatment.

"Can you think of anything worse one can do than take away someone's worship?" Dysart asks a friend in the course of rationalizing his absurd jealousy of Alan's psychosis. As a matter of fact, many things might be worse, including the expediency and irresponsibility that characterize the way Shaffer exploits Alan's act of volence as a pretext for glorifying Dysart's style of egotism.

While depicting a psychoanalytic breakthrough for theatrical purposes, Shaffer also uses Dysart to vent popular suspicions about psychitry and express fashionable leanings toward the occult and visionary. It's amusing to note that Dysart also recalls that old standby the defrocked priest, now transformed into an equivalent cliche, the self-hating shrink.

It's surprising that the role didn't seek out Richard Burton sooner than it did. After "The Night of the Iguana" and "The Sandpiper" and "Excorcist II," natural selection would have favored him for the movie Dysart even if he'd never prepped in the play. Perhaps it's not even a bad perfomance, but it seems that way, because Burton's very presence tends to accentuate the overbearing artificially of the character's emotional conflicts.

Peter Firth, recreating the role of Alan, which he originated, surpasses Michael Moriarty's bedraggled misery in "Report From the Commissioner," setting a new standard to avoid in unappealing representations of helplless victimization. Firths frazzled palor, gaping mouth and wobblu, shuffling gait create an impression so remote from the enviably ecstatic that Dysart's behaviour seems even loonier. He's jealous of this?

It remains uncertain, despite the presence of real horses, whether Alan developed a fixation on horses or a homoerotic fixation on a man riding a horse. The maiming is triggered by sexual episode that looks more dubious than ever, because a girl as attractive as Jenny Agutter's Jill seems increadibly wanton and perserves to lead on a boy as visibly disturbed as Peter Firth's Alan. When she says "You look weird" while trying to seduce him, you wonder where she's been looking all this time.