Einstein clearly knew about incubation: According to Clark (1971), Einstein would "allow the subconscious to solve particularly tricky problems. 'Whenever he felt that he had come to the end of the road or into a difficult situation in his work,' his eldest son said, 'he would take refuge in music, and that would resolve all his difficulties.'" (p. 106). Clark notes that for Einstein, "with relaxation, there would often come the solution" (p. 106).

Csikszentmihalyi and Sawyer (1995) interviewed nine "creative" individuals, all of whom had made creative contributions in their field, were 60 or older, and were still actively involved in creative work. All mentioned that insights occurred during idle time, and several mentioned that they occurred while they were doing something else, during a "repetitive, physical activity" such as gardening, shaving, taking a walk, or taking a bath (p. 348).

Mind on, mind off

This is not to say, of course, that hard work is unnecessary. Quite the opposite is true. Many studies confirm that high achievers put in a tremendous amount of work, far more than less accomplished colleagues. They engage in the "preliminary period of conscious work which also precedes all fruitful unconscious labor" (Poincare, 1924). This preliminary work is labeled "preparation" by Wallas, and as "wrestling with ideas" by Elbow (1972, p. 129). Wallas notes that the educated person "can 'put his mind on' to a chosen subjects, and 'turn his mind off' ...." (p. 92). The educated person knows how, in other words, to prepare and then incubate.

Of course, the "illumination" that is the result of incubation needs to be followed by more conscious work. Ideas that arise as a result of incubation need to be evaluated (Smith, 1994); our new insight may not be right.

Long and short incubation periods

Incubation sometimes requires a very long break: Feynman noted that "You have to do six months of very hard work first and get all the components bumping around in your head, and then you have to be idle for a couple of weeks, and then - ping - it suddenly falls into place ..." (Csikszentmihalyi and Sawyer, 1995, p. 350). Incubation can also occur with breaks of shorter duration. Piaget told Gruber (1995) that after he worked for a few hours, "he would go for a walk, not think about very much, and when he went back to his desk his ideas would be clearer ..." (p. 526). And it can also happen in very short breaks, a few minutes or even moments. In my experience, extremely short breaks are all that is necessary to solve many problems and loosen many blocks. In agreement with Wallas, I have found that these breaks work best when they are devoted to something fairly mindless: washing just a few dishes, filing just a few papers, or doing some light exercise.

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