Full Idea
Birds are empty-headed men who grew feathers instead of hair, because they were interested in astronomy but thought it was entirely a matter of physical evidence.
Gist of Idea
Only bird-brained people think astronomy is entirely a matter of evidence
Source
Plato (Timaeus [c.362 BCE], 91d)
Book Reference
Plato: 'Timaeus and Critias', ed/tr. Lee,Desmond [Penguin 1971], p.123