Simpson in: Elie Alexis Shneour (1966) Extraterrestrial Life: An Anthology and Bibliography. p. 269
George Gaylord Simpson: Frases em inglês
Splendid Isolation (1980) New Haven: Yale University Press. p. 38
Cited in: Edward J. Larson (2004) Evolution, Modern Library. p. 250
“Man is the result of a purposeless and natural process that did not have him in mind.”
George Gaylord Simpson (1967) The Meaning of Evolution, revised edition. New Haven: Yale University Press. p. 345.