[Émile Zola’s] was an intelligence that was willful, conscious, methodical, and seemingly made for mathematical deduction: it gave birth entirely to a romantic world. The other [Henri Poincaré’s] was spontaneous, little conscious, more taken to dream than for the rational approach and seemingly throughout apt for works of pure imagination, with subordination to reality: it triumphed in mathematical research. And this is one of the surprises, which calls for direct studies touching on the deepest mechanisms.
—Édouard Toulouse1
The French psychiatrist Édouard Toulouse pointed out the extraordinary fact that Zola—a novelist—thought like a scientist yet produced artistic creations, whereas Poincaré—a scientist—thought like an artist yet applied his poetic imagination to mathematical discoveries. For Toulouse, who was deeply interested in creativity, this apparent paradox demanded “direct studies touching on the deepest mechanisms.”2 I will begin my exploration of creativity with mechanisms like these, which are at the very heart of the creative process for us and to some extent for computers, too.