The essential point here is that there are several stages of creative thought: first, a stage of preparation in which the problem is consciously worked over then a period of incubation without any conscious concentration upon the problem; and then the illumination which is later justified by logic. The parallel between these important and complex problems and the simple problems of judging weights or the circle-triangle series is obvious. The period of preparation is essentially the setting up of a complex struction together with conscious attention to the materials on which the struction is to work. But then the actual process of reasoning, the dark leap into huge discovery, just as in the simple trivial judgment of weights, has no representation in consciousness. Indeed, it is sometimes almost as if the problem had to be forgotten to be solved.

• work
• thought
• consciousness
• attention
• logic