The Art of Thought– Graham Wallas's timeless 1926 model for the four stages of creativity – Preparation, Incubation, Illumination, and Verification – and how to master them.
In the daily stream of thought these four different stages constantly overlap each other as we explore different problems. An economist reading a Blue Book, a physiologist watching an experiment, or a business man going through his morning’s letters, may at the same time be “incubating” on a problem which he proposed to himself a few days ago, be accumulating knowledge in “preparation” for a second problem, and be “verifying” his conclusions on a third problem. Even in exploring the same problem, the mind may be unconsciously incubating on one aspect of it, while it is consciously employed in preparing for or verifying another aspect. And it must always be remembered that much very important thinking, done for instance by a poet exploring his own memories, or by a man trying to see clearly his emotional relation to his country or his party, resembles musical composition in that the stages leading to success are not very easily fitted into a “problem and solution” scheme. Yet, even when success in thought means the creation of something felt to be beautiful and true rather than the solution of a prescribed problem, the four stages of Preparation, Incubation, Illumination, and the Verification of the final result can generally be distinguished from each other.