An inventor, scientist or artist might work on one and the same project for a day, a week, a month, a year or many years. The thought processes associated with such extended activities are not equally creative throughout. Even when the work results in a creative product, much of what occurs along the way is analytical thinking or even habitual or routine behavior. What distinguishes creative from analytical processes is that the former are punctuated by insights, mental events in which new ideas come to mind. An extended project is likely to require more than one insight before completion. Projects vary with respect to the density of insight events, but each such event is of short duration compared to the duration of the project as a whole. I call this the Raisins in the Dough Principle.

To explain creativity is therefore to carry out three theoretical tasks: Describe analytical thinking, explain what happens in moments of insight and clarify how insight expands the power of analytical thinking.