I don't think I've ever been as happy in a place as I was in the Arctic, midwinter. The landscape had been simplified by darkness and snow but was actually full of traces of colour and light. And the most thrilling moment was towards the end of the day when there would be a kind of twilight which is called in Finnish 'sininen hetki' which means 'the blue moment'. And what astonished me about this light was that it didn't seem to come from the sky which was already dark, but from within everything around me, even from within myself and because so much of everything around me was covered in snow the blue that the evening released was very, very pure. When I came to write about it, I didn't want to compare this blue to anything - I wanted to retain something of its purity but of course I found I couldn't describe it. I couldn't explain what this blue was like without resorting to the different kinds of blue I already knew, so I decided in the end to construct what might be called an exercise in negative analogy - so instead of saying that the blue was like this or that I would describe all the things that it wasn't like at all.