The notion that Salieri might have killed his rival first surfaced dramatically exactly 100 years ago in Rimsky-Korsakov's opera Mozart and Salieri which, in turn, was based on Pushkin's short story, written five years after Salieri's death in 1825. If the idea was not new, Shaffer certainly made the most out of it. Indeed, bold theatrical effectiveness has been his hallmark in The Royal Hunt of the Sun through Equus to Lettice and Lovage. Thematically too, Amadeus ranks alongside them by hinging upon the struggle between equal opposites. Whether this stems from Shaffer being a twin - his brother Anthony wrote the successful thriller Sleuth - is anybody's guess, but his almost constant subject is of lives torn apart by envy.
Hidden in a wing-backed chair, Salieri overhears the foul-mouthed young Mozart cavorting outrageously with his latest love. Seconds later, in one of the play's best moments, his life changes forever upon hearing a Mozart wind serenade. Shaffer, formerly a music critic, brilliantly describes the emotional effect of the exquisite music, thereby opening both Salieri's and the audience's ears to Mozart's genius, at which point Salieri becomes consumed by fear. He believes he has heard God's voice "through the mouth of an obscene child" and the devout older man's fear turns to envy. Salieri believes that the gift of composing is divine and he rails at God for making him see himself as mediocre. This is a classic Shaffer ploy, juxtaposing ideas and making them appear as watertight argument. Seething with hatred, Salieri swears to ruin the life of his rival whom he sees as God's chosen instrument.
But the question of why Salieri should make the leap of directly linking Mozart with God is never satisfactorily answered. Theatrically, however, it pays dividends as God appears to be on Salieri's side as his star blazes, thus giving him the power to mastermind scenes of Mozart's downfall.
The problem with the play - in addition to endless cumbersome expository scenes over-earnestly staged by Peter Hall - is that the often prosaic writing rarely matches the inspiration of the ideas. The flatness of the dialogue can be overcome through sheer power but although David Suchet is great at suppression and the masking of powerfully conflicting emotions, he's less good at Salieri's necessary blistering rage.
Shaffer's Mozart is an inspired but scatalogical buffoon - yet thanks to Michael Sheen's thrilling performance you never doubt his character's genius. He's alive with passion, a terrifying energy boiling up through his body and pouring off him. Ironically, in an evening which should really belong to Salieri, it's Mozart who gives it its strength.