Etymology
Advertisement
black sheep (n.)

by 1792, in the figurative sense of "person of bad character; member of some group guilty of offensive conduct that does little credit to the flock, family, or community to which he belongs," supposedly because a real black sheep (there was proverbially one in every flock) had wool that could not be dyed and thus was of less worth. But one black sheep in a flock was considered good luck by shepherds in Sussex, Somerset, Kent, Derbyshire. First known publication of Baa Baa Black Sheep nursery rhyme is in "Tommy Thumb's Pretty Song Book" (c. 1744).

Related entries & more 
Advertisement
mouton enrage (n.)

"A normally calm person who has become suddenly enraged or violent" [OED], 1932, from French mouton enragé, literally "angry sheep." See mutton + enrage.

Related entries & more 
middle passage (n.)

"part of the Atlantic Ocean which lies between the West Indies and the west coast of Africa," 1788, in the agitation against the trans-Atlantic slave trade, from middle (adj.) + passage.

It is clear that none of the unfortunate people, perhaps at this moment on board, can stand upright, but that they must sit down, and contract their limbs within the limits of little more than three square feet, during the whole of the middle passage. I cannot compare the scene on board this vessel, to any other than that of a pen of sheep; with this difference only, that the one have the advantages of a wholesome air, while that, which the others breathe, is putrid. [Thomas Clarkson, "An Essay on the Slavery and Commerce of the Human Species," 1788]
Related entries & more