“If you wish to upset the law that all crows are black, you mustn't seek to show that no crows are; it is enough if you prove one single crow to be white.”

Leggiadre donne, infra molte bianche colombe aggiugne più di bellezza uno nero corvo, che non farebbe un candido cigno.
Ninth Day, Tenth Story
The Decameron (c. 1350)

Flowers of Wisdom

Source: Starman Jones (1953), Chapter 11, “Through the Cargo Hatch” (p. 111)

Song lyrics, The Firstborn Is Dead (1985), Black Crow King

Source: Peter and Wendy (1911), Ch. 17
Context: The last thing he ever said to me was, "Just always be waiting for me, and then some night you will hear me crowing."

Review http://www.salon.com/ent/movies/review/2001/12/14/vanilla/index.html of Vanilla Sky (2001)

1960s, How Long, Not Long (1965)
Context: If it may be said of the slavery era that the white man took the world and gave the Negro Jesus, then it may be said of the Reconstruction era that the southern aristocracy took the world and gave the poor white man Jim Crow. He gave him Jim Crow. And when his wrinkled stomach cried out for the food that his empty pockets could not provide, he ate Jim Crow, a psychological bird that told him that no matter how bad off he was, at least he was a white man, better than the black man. And he ate Jim Crow. And when his undernourished children cried out for the necessities that his low wages could not provide, he showed them the Jim Crow signs on the buses and in the stores, on the streets and in the public buildings. And his children, too, learned to feed upon Jim Crow, their last outpost of psychological oblivion. Thus, the threat of the free exercise of the ballot by the Negro and the white masses alike resulted in the establishment of a segregated society. They segregated southern money from the poor whites; they segregated southern mores from the rich whites; they segregated southern churches from Christianity; they segregated southern minds from honest thinking; and they segregated the Negro from everything. That’s what happened when the Negro and white masses of the South threatened to unite and build a great society: a society of justice where none would pray upon the weakness of others; a society of plenty where greed and poverty would be done away; a society of brotherhood where every man would respect the dignity and worth of human personality.

§ 4
From Lives and Opinions of the Eminent Philosophers by Diogenes Laërtius