Link: How I Write by Bertrand Russell.
Here is a brief except:
Very gradually I have discovered ways of writing with a minimum of worry and anxiety. When I was young each fresh piece of serious work used to seem to me for a time-perhaps a long time-to be beyond my powers. I would fret myself into a nervous state from fear that it was never going to come right. I would make one unsatisfying attempt after another, and in the end have to discard them all. At last I found that such fumbling attempts were a waste of time. It appeared that after first contemplating a book on some subject, and after giving serious preliminary attention to it, I needed a period of sub-conscious incubation which could not be hurried and was if anything impeded by deliberate thinking. Sometimes I would find, after a time, that I had made a mistake, and that I could not write. the book I had had in mind. But often I was more fortunate. Having, by a time of very intense concentration, planted the problem in my sub-consciousness, it would germinate underground until, suddenly, the solution emerged with blinding clarity, so that it only remained to write down what had appeared as if in a revelation.
I bet your want to see how he does it.