Konrad Lorenz, On Aggression
, tr. Marjorie Kerr Wilson (New York: Harcourt, Brace & World, 1966), chap. 6 (The Great Parliament of Instincts
Some of those special drives which guarantee a permanent aggregation of social animals rule the individual so strongly that under certain conditions they can supersede all other drives. The sheep that leaps over the precipice after the leader ram has become proverbial. A greylag goose that has become separated from the flock does everything in its power to find it again, and the drive toward the flock can even overcome the escape drive. Wild geese have repeatedly joined our tame ones in the immediate neighborhood of human habitations and remained there. When one knows how shy wild geese are, one can imagine the power of the herd instinct. Similar behavior occurs in a great many social vertebrates, up to chimpanzees, of which Yerkes rightly said, "One chimpanzee is no chimpanzee."
Up to human beings, as well. There is a similar Greek proverb εἶς ἀνὴρ οὐδεὶς ἀνήρ
= "one man [is] no man." Gildersleeve, Syntax of Classical Greek
(New York: American Book Company, 1900), lists it as an example under "Position of the attributive adjective," and Crosby and Schaeffer, An Introduction to Greek
(Boston: Allyn and Bacon, 1928), include it as a motto for lesson LVI. I cannot find an exact source in ancient Greek literature. Many college fraternities use it as a motto. Whether Robert M. Yerkes (1876-1956) ever studied Greek or joined a fraternity, I don't know. He graduated from Harvard in 1898.