THEATRE / Shining in the shadow of the two suns: Neal Ascherson was seized by Robert Lepage's new show

I saw the Edinburgh production of 'The Seven Streams of the River Ota' this summer, and I nearly left after the first act. The production seemed at once baffling and trivial. Luckily, a friend I met during the interval warned me that Robert Lepage knew what he was doing, and that if I stayed I would see the point. Going mistrustfully back into the auditorium, I found myself facing one of the most seizing theatrical moments in my life, and the Lepage method slowly became clear. This is a piece I wrote afterwards as a programme note for later productions.

WHEN people in Hiroshima looked into that flash, 'brighter than a thousand suns', their eyes melted and ran down their faces.

In the half-century that followed, no artist or writer has been able to look directly into that instant of appalling light. Instead, it has been refracted through innumerable lenses. Some delivered that illumination of fear - the anticipation of universal death - which coloured everything during the decades of nuclear confrontation. Other lenses broke up the light into trivial glitters to give illusions of profundity to some junk novel or television play. At the same time, as people began more slowly to grasp the details of the Jewish Holocaust in the years immediately before Hiroshima, a second, black sun rose into which it proved impossible to look directly without being blinded. Claude Lanzmann, in his film Shoah, revealed as much as is possible by using the smoked glass of personal recollections. But nobody who has tried to confront what took place directly has survived as an artist.

Robert Lepage, in The Seven Streams of the River Ota, is setting out to construct a masque of the later 20th century. More precisely, he is letting this extraordinary production construct itself like a sort of coral reef, slowly changing and growing larger with each performance. Over the whole era since the 1940s hang the white sun and the black sun, Hiroshima and Holocaust, and Lepage has found that the only way to collect and transmit their glare is by filling his stage with lenses. This is made literally true, by a triumphant use of mirrors. But it is figuratively true as well. The heartbreaking personal narrative, the emphasis on the disguises of photography, Lepage's selection - at first violently shocking - of high farce or bed-hopping sitcom as dramatic modes: these are all lenses through which the unbearable light source is broken up into spectrum colours and spread out for an audience to appreciate.

In this way, Lepage has made it possible to see - or to begin to see and to explore - how human culture has developed in the light of the two suns. His drama is about survivors. But it is also about the way in which the loneliness of the survivors, the impossibility of telling others what it was like to be where they have been, has permeated all sensual experience with uncertainty and melancholy - as if generations born decades after the atom bomb and the gas chambers still carried in their genes an amazed sense of survival. The concentration camp at Theresienstadt, in which families waiting to be transported to Auschwitz were encouraged by the Nazis to develop a rich, 'normal' cultural life of concerts and entertainments, prefigured this unease and this feeling of unreality. The great flash in the Hiroshima sky, by which a city was illuminated and then instantly eradicated, is also the flashbulb of the photo-booth in which people freeze their own desires and use an image to obliterate their old identities. The encounters between cultures once mutually unknown have entirely metamorphosed the world since 1945, but these encounters seem to look back over their shoulder at the time when to be 'other' - Jewish or Japanese - was to be condemned to death.

Lepage, finally, is working at the idea that sexuality itself, the fact of gender and the patterns of behaviour around it, were pitched into mutation by the rays from the two suns. This is not some easy revisiting of Eros and Thanatos, but the thought that the human species is leaving behind its old binary division altogether, exploring an entirely new range of responses to love and procreation. Where this exploration will go is as unpredictable as where Lepage's growing, organic work of art will eventually take him - the unknown point at which the Seven Streams of the River Ota converge.

'The Seven Streams of the River Ota': Riverside Studios, London W6 (081-741 2255), Fri to 5 Nov. Sponsor: Beck's beer.

(Photograph omitted)