Wit

What makes us who we are? Is it the sum of our biological parts - limbs, a torso, a head, a face? Or is it something less tangible, less corporeal? Put another way: what is the meaning of life? This is perhaps the biggest, most infinitely complex and elusive question humanity has ever asked of itself, so it's little wonder that man's greatest minds have often wrestled with the subtleties of the human condition in search of an answer (if indeed there is one).

One of these towering intellects was John Donne, the 17th-century metaphysical poet, whose verse, tussling with the ineffable idiosyncrasies of the soul, rank among the most meticulously crafted ideas ever committed to paper. The fact that the essence of Donne's genius has been captured and preserved for centuries is an extraordinary thing; in one sense, we can still engage in a conversation with this man, as his brilliance reaches out across the ages. But of course, this connection isn't real. Donne is dead. His body and brain have rotted away, and while his ideas endure, his mind - active, vibrant and alive - is long gone.

This paradox is the thematic bedrock upon which Margaret Edson's 1996 Pulitzer Prize-winning play Wit is built. It pits the conceit that the body is merely a vehicle for the mind, against the unignorable truth that one cannot persist without the other.

A ferociously intelligent professor, specialising in the poetry of Donne, Vivian Bearing, has stage four ovarian cancer. There is no stage five: she is dying. As her body fails, her brilliant mind processes the experience in the careful vernacular of an arch-academic. She trades in multisyllabic, curdling, opaque eloquence that revels in its own dense exclusivity. She is not without passion, indeed Bearing's ardent admiration for Donne borders on the obsessive. But it is devoid of sentimentality – anything so mawkish is miles beneath her. And yet, as her aggressive cancer and the even more aggressive treatment attack her body, her ironclad tank of a brain is overwhelmed by the emotions this agony provokes. As Bearing remarks, she is once more a student: "I am learning to suffer."

Not unlike Donne, Edson has crafted a virtuosic and colossally cerebral text, and in the wrong hands, its remarkable insight could easily be squandered. It requires a performer with an equally virtuosic skill to communicate all its subtleties, someone who understands every microscopic variant on the full spectrum of human emotion. Fortunately, the Artisan Collective's production at Fortyfivedownstairs is blessed with a performer of this category.

Jane Montgomery Griffiths as Professor Bearing delivers a performance of such unrestrained commitment that even now, hours after the end of this production, I'm fighting back tears just to think of it. This role turns on a pin-head from the voice of a narrator - charming, charismatic and often quite funny - to the stark, brutal realities of losing a battle to cancer. This production doesn't sugar-coat any facet of this harrowing account. It is undignified, deeply shocking, and like Jeminah Alli Reidy's superbly realised wire-frame set, completely exposed. Montgomery Griffiths offers a masterclass in emotional authenticity, bringing a level of forensic detail to her portrayal that I have very rarely seen on stage. Quite simply, her performance is astonishing.

She is accompanied by a strong supporting cast, although with a lead as incandescent as Montgomery Griffiths, the juxtaposition is inevitably a little unflattering. Jing-Xuan Chan as cancer nurse Susie Monahan is a well-judged foil for Bearing. She is a mirror opposite of the dying Professor, compassionate, uncomplicated and pragmatic. Her warm yet grounded care for Bearing, as fear and pain corrode the Professor's mental faculties, reveal some of the most touching moments in this production, but by far the most arresting scene comes between Bearing and her mentor, Professor Ashford, played by Helen Morse.

In her final days, defeated by excruciating treatments and unstoppable tumours, Bearing is visited by her old teacher. Unable to converse or intellectually spar as they once did, Ashford offers a gesture of uncharacteristic kindness, simply holding her old pupil. It is a moment that is simultaneously heartbreaking and yet profoundly affirming.

I urge you not to miss this brief Melbourne season, and not only because it is a tour de force of accomplished acting. Wit offers an incredibly important perspective on a subject that, after centuries of scrutiny, could easily be threadbare.

The Artisan Collective presents Wit, at Fortyfivedownstairs to 17 Sep.