Writing is a concentrated form of thinking . I don’t know what I think about certain subjects, even today, until I sit down and try to write about them. Maybe I wanted to find more rigorous ways of thinking. We are talking about the earliest writing I did and about the power of language to counteract the wallow of late adolescence, to define things, to define muddled experience in economical ways: Let’s not forget that writing is convenient. It requires the simplest tools … A young writer sees that with words and sentences … He can place himself more clearly in the world. Words on a page, that’s all it takes to help him separate himself from the forces around him … He learns to think about … things, to ride his own sentences into new perceptions.
I tend to agree. It's true not just for "a young writer." Nor is it true just for fiction.
1. The Paris Review, The Art of Fiction No. 135