Gullivers Travels Part 4 Chapter 9 Page 13

before their death, which they seldom fail in computing, they return the visits that have been made them by those who are nearest in the neighbourhood, being carried in a convenient sledge drawn by Yahoos; which vehicle they use, not only upon this occasion, but when they grow old, upon long journeys, or when they are lamed by any accident: and therefore when the dying Houyhnhnms return those visits, they take a solemn leave of their friends, as if they were going to some remote part of the country, where they designed to pass the rest of their lives.

I know not whether it may be worth observing, that the Houyhnhnms have no word in their language to express any thing that is evil, except what they borrow from the deformities or ill qualities of the Yahoos. Thus they denote the folly of a