Albert Einstein was considered at school as a bogus because he always had his head in the clouds. His name is now used as synonymous with genius. Is there a link between his scientific creativity and his state of mind?

Many Studies prove that yes, there is one.

For instance, Ut Na Sio and Thomas C. Ormerod state that: “When solving a creative problem, individuals benefit from performing a wide search of their knowledge to identify as many relevant connections as possible with the presented stimuli. Each time individuals reapproach the problem, they improve their per- formance by extending the search to previously unexplored areas of their knowledge network.” I invite you to read Does Incubation Enhance Problem Solving? A Meta-Analytic Review Ut Na Sio and Thomas C. Ormerod – Lancaster University:

and the Wikipedia article on  Incubation (psychology):

Jacques Higelin, Tombé du ciel: