The prologue to Don Quijote de la Mancha is one of my single favorite pieces of literature. The artistry of the prose, combined with the humor of the whole thing and Cervantes' takedown of the more pretentious habits of his fellow writers combine into an amazing whole. I'd like to translate the whole thing, so won't post it here just yet.
Instead, have this blurb from a letter written by Laurence Sterne to Ignatius Sancho, a free black man living in England in the mid-18th century. Sancho had asked Sterne to write in favor of the abolitionist cause, saying
That subject, handled in your striking manner, would ease the yoke (perhaps) of many — but if only one — Gracious God! — what a feast to a benevolent heart!
Sterne, meanwhile, was in the middle of writing Tristram Shandy, which contains a conversation between two characters bemoaning the poor treatment of a black servant in a shop. Sterne's response is great, and became widely quoted among abolitionists in the UK:
There is a strange coincidence, Sancho, in the little events (as well as in the great ones) of this world: for I had been writing a tender tale of the sorrows of a friendless poor negro-girl, and my eyes had scarce done smarting with it, when your letter of recommendation in behalf of so many of her brethren and sisters, came to me — but why her brethren? — or yours, Sancho! any more than mine? It is by the finest tints, and most insensible gradations, that nature descends from the fairest face about St James’s, to the sootiest complexion in Africa: at which tint of these, is it, that the ties of blood are to cease? and how many shades must we descend lower still in the scale, ere mercy is to vanish with them? — but ’tis no uncommon thing, my good Sancho, for one half of the world to use the other half of it like brutes, & then endeavor to make ’em so.