Gullivers Travels Part 4 Chapter 9 Page 6

animal, and held the Houyhnhnms in servitude; that he observed in me all the qualities of a Yahoo, only a little more civilized by some tincture of reason, which, however, was in a degree as far inferior to the Houyhnhnm race, as the Yahoos of their country were to me; that, among other things, I mentioned a custom we had of castrating Houyhnhnms when they were young, in order to render them tame; that the operation was easy and safe; that it was no shame to learn wisdom from brutes, as industry is taught by the ant, and building by the swallow (for so I translate the word lyhannh, although it be a much larger fowl); that this invention might be practised upon the younger Yahoos here, which besides rendering them tractable and fitter for use, would in an age put an end to the whole species, without destroying life; that