I went to see Black Swan last night and came back horrified. How could the director, Darren Aronofsky, have ...

Hang on. If you haven't seen the film and plan do do so, you'd better stop here, and come back to this blog when you have seen it. I don't want to spoil your enjoyment - I was gripped by 99% of the film.

Where was I? Yes ... how could Aronofsky handle the film so brilliantly throughout and then blow it in the very last sequence? Nina is lying on the mattress backstage ... the applause is roaring in our ears ... Thomas bends over and says "They love you" ... and then finds out that she's bleeding heavily. What? She has apparently danced the last act of Swan Lake with a severe abdominal wound - no, the last two acts, because the mirror gets broken before she goes out to dance the Black Swan in Act Two. This is surely unbelievable.

The point is that Aronofsky has danced along the dividing line between the literal and the metaphorical throughout the film - with great success up to this moment. We have been deeply involved in Nina's struggle to come to terms with the problem of dancing the (good) White Swan and the (bad) Black Swan in the same performance. Our sense of what is real has been gradually eroded, in parallel with Nina's own increasing confusion. What are these strange marks on her body? Why these episodes of bleeding? Who is Lily, and what is her relationship with Thomas - or with Nina? The film convinces precisely because our struggle to make sense of what is going on closely reflects Nina's own struggle - the film becomes a metaphor of the conflict between the metaphorical and the real.

Aronofsky controls this conflict magisterially, and grips our attention. For instance, the 'killing' of Lily in the dressing room, with glass from the broken mirror, is shown as convincingly real, and we understand that Nina hides the body, in her determination to dance the part, and then goes out to give a sublime performance driven by the evil of what has just happened. But then ... she gets back to the dressing room, and there's no body, no blood, and Lily is obviously alive enough to knock on the door and congratulate her (although the mirror has been broken). So we understand that the killing has been metaphorical, an imaginative violence that has enabled Nina to grasp how to dance the Black Swan.

The film functions, and functions well, on many interconnected levels. In essence, the metaphor of Black/White in the ballet leads to Nina's professional problems in handling the Black/White roles, which in turn are affected by Nina's own personal problems in sorting out the Black/White elements of her life and personality - and while we watch, we are landed in interpretive problems as we attempt to sort out what Black/White means within the reality of the film, all of which refers finally to what we understand of Black/White in terms of the real world.

Which is why it is such a disaster when the metaphorical is collapsed into banal reality at the end - when the shard of glass turns out to have caused a very non-metaphorical terrible injury (but how? when? why?), and Nina has apparently been bleeding to death while giving the performance of her life. Either the shard of glass is metaphorical, expressing Nina's anguish (in which case she can't be bleeding to death); or it is real (in which case she couldn't have danced). I can suspend disbelief with the best ... but there are limits.