An interview at The Paris Review:
It’s not like writing in a diary, though. A novel opens space between a writer and his or her material, the space of literature. There’s less distance between writer and diary than between writer and novel.
It’s all the difference in the world. I had tried to write from the age of eighteen, but didn’t succeed at all. Then, when I was about twenty-seven, I changed my language. This is difficult to explain. You can write a radical Norwegian or a conservative Norwegian. And when I changed to a conservative Norwegian, I gained this distance or objectivity in the language. The gap released something in me, and in the writing, which made it possible for the protagonist to think thoughts I had never myself thought.
But it isn’t only about language. There’s a kind of objectivity in the form itself. It is not you, it is not even yours. When you use the form of a novel, and you say “I,” you are also saying “I” for someone else. When you say “you,” you are simultaneously in your room writing and in the outside world—you are seeing and being seen seeing, and this creates something slightly strange and foreign in the self. When you see that, or recognize that, you are in a different place, which is the place of the novel or the poem.
In Min Kamp, I wanted to see how far it was possible to take realism before it would be impossible to read. My first book had a strong story, strong narration. Then I would see how far I could take a digression out before I needed to go back to the narration, and I discovered I could go for thirty or forty pages, and then the digressions took over. So inMin Kamp I’m doing nothing but digressions, no story lines. Language itself takes care of it. The form gives something back.
more here.