Bertrand Russell said, "I have found, for example, that, if I have to write upon some rather difficult topic, the best plan is to think about it with very great intensity—. the greatest intensity of which I am capable—for a few hours or days, and at the end of that time give orders, so to speak, that the work is to proceed underground. After some months I return consciously to the topic and find that the work has been done. Before I had discovered this technique, I used to spend the intervening months worrying because I was making no progress; I arrived at the solution none the sooner for this worry, and the in­tervening months were wasted, whereas now I can devote them to other pursuits." (Bertrand Russell, The Conquest of Happiness, New York, Liveright Publishing Corpora­tion.)