We usually think of the human brain as a single organ, but it is a complex assembly of modules that process different kinds of information in quite different ways. Somehow, we construct a rich world of objects out of the two-dimensional images projected onto our retinas through two tiny irises—effortlessly, and in real time. Human abilities here still far outstrip even the most powerful computers. Analytical processing of more abstract symbolic information, such as mathematical formulas or logical schemas (like family trees, recipes or computer programs), occurs elsewhere. Visualization is the art of getting those two...