THEARTRE / Lore of diminishing returns: They said it of Faith Healer, now they're saying it of Brian Friel's new play, Molly Sweeney. 'Masterpiece'. They may share similar preoccupations, says Paul Taylor, but there the comparision ends

If any contemporary playwright might be said to have produced work that's been touched, on occasion, by outright genius, it's the Irish dramatist Brian Friel, whose latest play, Molly Sweeney, begins previewing next week at the Almeida in London. When this piece was unveiled in Dublin last August, its close affinities in form and theme to Friel's masterpiece Faith Healer (1979) encouraged many critics to imply that here was a work which matched that earlier play in poetic reach and intensity.

The Observer, for example, referred to its 'already guaranteed classic status', while the Guardian roundly declared it 'triumphant'. The Financial Times, nearer to my own view, described it as 'mere self-parody' but spoilt its case by not even mentioning, let alone examining, the strongest evidence for this claim (ie Faith Healer) and by the flip disrespectfulness of its tone. I want to suggest that Molly Sweeney bears the same relation to Friel's masterwork as a highly talented fake does to the real McCoy, and that to fail to distinguish between these two levels of achievement does Friel no favours. It merely bolsters this fine playwright in the apparently sincere illusion that he has managed to make lightning strike twice. Molly Sweeney is, in fact, more a case of already stolen thunder.

Like Faith Healer, the new piece consists entirely of direct-to-audience monologues delivered by two male characters and one female. Once again, Friel's metaphysical preoccupations with art, the miraculous, exile, identity and the unconscious are approached through the highly equivocal topic of healing. By comparison with the earlier work, though, there is something deadeningly clear-cut about the way this trio of speakers are ranged thematically.

Molly Sweeney, unsighted for nearly all of her 40 years, is persuaded by two men to have an eye operation and so forfeit her sensorily privileged experience of the world. The men, in their consuming need to restore themselves through 'curing' Molly, are offered as heavy-handed exemplars of moral blindness. Just in case you haven't got the already deafening message that, for Frank, her unfulfilled crank of a husband, she's simply the latest of his crackpot projects, it's obligingly spelt out for you: 'all part of the same pattern, sweetie: bees - whales - Iranian goats - Molly Sweeney'.

And as for Rice, the once high-flying ophthalmologist whose career went into whiskey-sodden decline when his wife left him, the ironies of being a blinkered restorer-of-sight are hammered home via the neurological vocabulary. This serves both to describe Molly's eventual alienated withdrawal from the baffling sighted world (which she can see but not understand) and Rice's moral failure, throughout his life, to see what was right under his nose. The equivalence strikes you as too patly convenient, though.

The elements which in Molly Sweeney are distributed so inertly among the characters were disturbingly united, to the great benefit of the earlier play, in another Frank, the eponymous Faith Healer. This Frank is an Irishman working in exile on the Celtic fringes of the mainland and caught in the grip of a capricious gift he can neither comprehend nor control.

Self-estranged, he is both Molly and purblind, single-minded Rice.

But although there is pointed talk of ophthalmologists 'performing', Rice's surgical skills don't provide as powerful an analogy with the operations of the artist as the dodgy ministry of Faith Healer's Frank.

Frank's faith healing is wholly at the mercy of inspiration and, from guilt at his self-centred life, he has a compulsion to convert fact into fiction.

Rice applies skill that is neutral in itself for the wrong reasons to the wrong person and causes disaster followed by a troublingly willed victory.

Frank's gift, however, is morally ambiguous through and through. It inextricably intertwines the destructive and the creative, harming / healing both performer and bystander and wilfully antagonising Irish society, where the artist is treated with either corrupting veneration or deadly contempt.

It's this nagging insolubility at the heart of Faith Healer that lends it the painful obsessiveness on which the monologue form thrives. Compared to its beautifully structured sequence of long solo turns and artfully discrepant versions of the past, the constant chopping and changing between the trio in Molly Sweeney, who are all on stage at once, has an unfortunate air, at times, of That's Life] As with Wonderful Tennessee (1993), the other new work he has unveiled since his international hit, Dancing at Lughnasa, you feel a sense of inverted priorities and that the metaphysics of the piece and the thesis Friel wants to draw are dictating what happens on the primary level. You don't need to have seen Synge's analogous Well of the Saints (a play in which an ugly, blind, beggar couple are cured by a saint and lapse into stunned mutual loathing before opting for the comforts of sightless illusion) to wonder at the absence of talk about sex and physical attraction in Molly Sweeney and to wonder about how restored sight affects that side of a relationship.

Unseeing is believing. Stay in the dark you have grown accustomed to: this message of sad resignation is conveyed, ironically, in a play in which Friel has stayed with devices and effects he (and we) have grown accustomed to.

(There's yet another ecstatic dance releasing defiant, primitive impulses).

Unlike the critic of the Observer, who feels this work marks 'an unequivocal return to form', I think it's time for this vastly gifted playwright to move on.

A direct contrast can be made with Alan Bennett. On a recent edition of Kaleidoscope, he revealed that, ever since Talking Heads first went out, he has been struggling - fruitlessly - to write follow-ups. But those monologues, he felt, had been 'given' to him (they had, in a sense, composed themselves) and he had come to the conclusion that that was the only honest way more would ever get written. Faith Healer, too, has the (perhaps deceptive) air of being 'given', but, unlike Bennett, Friel has not had the good sense to refrain from manufacturing a 'repro'-version.

'Molly Sweeney' begins previewing at the Almeida, London N1 (071 359 4404) from 27 October; it opens 3 November (Photographs omitted)