"R. N. Shepard [1978] has argued that a number of highly original and significant creations of the human mind have been produced by a mode of thinking which was essentially nonverbal, involving internal representations which could best be described as images of a largely spatial, and often visual character. Shepard provides an impressive list of creative scholars whose most outstanding achievements have been the result of highly visual thinking: Einstein, James Clerk Maxwell, Michael Faraday, Hermann von Helmholtz, Francis Galton, and Friedrich A. Kekule are on the list as is the mathematician ."