„The outlook of a Bruno, a Kepler, or a Galileo is determined by the idea of a comprehensive, all-embracing unity of the physical world. The same law governs the courses of the stars, the falling of stones, and the flight of birds. This homogenization of the physical world with respect to the validity of law deprives the division of physical objects into rigid abstractly defined classes of the critical significance it had for Aristotelian physics, in which membership in a certain conceptual class was considered to determine the physical nature of an object.“
— Kurt Lewin German-American psychologist 1890 - 1947
Fonte: 1930s, A Dynamic Theory of Personality, 1935, p. 10 as cited in: Coleman Roberts Griffith (1943) Principles of systematic psychology. p. 215.