birds of a feather flock together
- ^ http://classics.mit.edu/Plato/republic.2.i.html
- Gregory Y. Titelman, Random House Dictionary of Popular Proverbs and Sayings, 1996, ISBN 0-679-44554-4, p. 31 .
The expression appears to have surfaced in the 16th century, allegedly a literal translation of Plato's Republic. In 1545, William Turner wrote a version of the expression in The Rescuing of Romish Fox: "Byrdes of on kynde and color flok and flye allwayes together."reference needed