The development of design principles based on objective visual tests, experience, and logic; the pursuit of research in the physiological and psychological effects of color; and investigations in perceptibility and readability in typography are being carried on in other fields... such a movement in cartography cannot fail to materialize

p. 13-14; As cited in: Clifford H. Wood, C. Peter Keller (1996) Cartographic design: theoretical and practical perspectives. p. 21 - The Look of Maps (1952)