But let's start by admitting that the play is difficult. After all, it's a medieval religious text, never meant for performance, crafted by Johannes von Saaz of Bohemia (c. 1350-1414), staged as a debate between the spirit of death and a farmer in mourning for his young wife. Drawing on antique patterns of rhetoric and argument, it's replete with dated and esoteric vocabulary: "feculent", "alectryomancy", "Rubicon". It's didactic and lengthy, repetitive, lacking in plot, and its 90-minute running time is untempered by an intermission. Consequently, I'm willing to forgive the young for fidgeting, and the weary for falling asleep.

And yet Death and the Ploughman is also beautiful - and by this I don't mean florid in wide strokes, with showers of petals and high-kicking houris - rather, it sustains an arresting visual aesthetic through its extremely stylised light, sound and movement. SITI Company's trademark blend of the Suzuki and Viewpoint acting methods instills the actors with a constant dynamism and deliberateness of action. And this can be seen from the very start as the audience enters a theatre of gradually pulsing lights where the three players stand in position, not immobile, but moving slowly as if through viscous water. Their precisely choreographed movements mirror, dodge, and clash with each other, tinged with polysemy but never quite corresponding to the literacy of the text.

It is this relentless, deliberate beauty that ensures that every moment of the play remains purposeful and alive. It buoys up the weight of the difficult text, allowing it to become almost music, exquisite even without attention to its meanings, and spiritually dazzling once one actually listens to the warring declarations of the sanctity and futility of human life. This could be why the crowd of convent schoolgirls in the circle seats audibly laughed at certain points in the play - at appropriate and inappropriate junctures - demonstrating that as fiendishly intellectual a piece like this does speak across purported barriers of age.

I have to pause a while to remark on the specifics of the play's dynamics. Death (Stephen Webber) is portrayed as a lofty, pompous, dispassionate, occasionally annoyed gentleman in a black suit and bowler hat and with an umbrella that never leaves his hand, while the Ploughman (Will Bond) is distinctly proletariat, dressed in work clothes, tortured, grieving, but perspicacious and clever. This isn't a game of heroes and villains: both death and the Ploughman make valid and sympathetic philosophical points. And although the Ploughman at times succeeds in provoking Death to the point of growling like a beast, it is plain that he is at war not against a devil that must be expelled, but against the ineffable.

Bogart's great coup, however, was in conjuring up the role of the Woman (Ellen Lauren), a barefoot lady in a white dress. At first the Woman embodies the perfect, virtuous qualities of the Ploughman's dead wife, heightening the tragedy of his loss. But a quarter of the way through the play, she joins Death in speaking the harsh truth of inevitable doom, and the contrast between her strong, deep voice and her slight figure creates a dramatic disjuncture of delicacy and power. As a third player, Lauren expands the dimensions of the piece - she is the yin to Webber's yang, and the two together are emblematic of Death as a balancing force, even suggesting that the dead whom we miss speak on behalf of Death itself. They even break the prevailing mood of the play to form an absurd vaudeville team, viciously celebrating the gory totality of death in this world with a series of mock-murders - and this gallows humour rejuvenates the otherwise somber play.

The close of the play brings us back to the bare of bones of the theatrical medium. Death and the Ploughman call on God to judge between them and are confronted suddenly with silence as the music abruptly stops. They begin to reenact the blocking of the play randomly and at triple-speed to the sounds of a black spiritual, muttering the beginnings of cues and crashing into each other - a bizarre kind of apocalypse, as the past body of the play arises again in the form of its component skeletal parts. Then, with all the stage presence that a deus ex machina demands, the Woman speaks the part of God, telling the parties they have both argued well, and while the honour may go to the Ploughman, the victory goes to Death.

A day later, Bogart explained to us in a lecture how she believes that in an age of imprecise speech, "The most radical thing you can do is to finish your sentence." It's this sense that I get from watching Death and the Ploughman: a presentation of clear and immortal ideas that might have mouldered away in the library, but have now been brought to life on stage. Certainly, there's profit to be gathered from a contemporary TheatreWorks-style presentation like The Global Soul, where cultures brush against each other, speaking different languages, building toward a transcendent point. But it's so seldom today that we see articulate, thoughtful speech being delivered in a dramatic context. What the SITI Company have accomplished is extraordinarily powerful, transmuting transforming dry prose into poetry, creating a theatre of ideas themselves.

This is the first time I'm giving a full five stars to a production. And I'm aware that many may have found this play intellectually exhausting, unpopulist, and tiresome - even I was disturbed by the unamplified volume of the actors' voices, though an acting friend told me that microphones cause the lungs to be lazy.

Yet I am floored by the remarkable ambition of Death and the Ploughman, and the immense degree to which it succeeded in resuscitating a work apparently so intellectual that many would have said it should never have come to the theatre. This play makes you consider the bare facts of being human on this earth where all is mortal - and when did you last see a professional production that dared to do that? The piece is fabulously concerted, blending light, sound, movement and text into a spellbinding blue-note harmony. If I can't bear Bogart's children, I'll just aspire to create theatre of her standards - classically contemporary, fiendishly beautiful, and breathtakingly difficult.