Gulliver tries to explain that the Yahoos are the governing creatures where he comes from, and the Houyhnhnms ask how their horses are employed. Gulliver explains that they are used for traveling, racing, and drawing chariots, and the Houyhnhnms express disbelief that anything as weak as a Yahoo would dare to mount a horse that was so much stronger than it. Gulliver explains that the horses are trained from a young age to be tame and obedient. He describes the state of humanity in Europe and is asked to speak more specifically of his own country.
In the fourth voyage, Gulliver reaches a stage at which he no longer cares for humankind at all, though in this section we see only the beginnings of his transformation. After visiting countries in which he is too large, too small, and too down-to-earth, he finds himself in a country where he is neither rational nor moral enough, stuck in the limbo between the humane Houyhnhnms and the untamed, unruly Yahoos. In these chapters we see the rough outline of Houyhnhnm society, which Gulliver finds pleasant but still alien. In the next section, he attempts to become a part of this society.
In the meantime, we are treated to a description of the Houyhnhnms’ society. Swift plays a clever trick in the first two chapters, obscuring the true nature of the Houyhnhnms so that we follow Gulliver in his mistaken belief that the horses are magicians or the servants of a magician. Instead of telling us outright that the horses are intelligent, Swift allows us to discover this fact through Gulliver’s eyes. As a result, what looks strange to Gulliver also looks strange to us, and at some point in the description of the horses’ behavior, we realize that there is nothing more to these creatures than meets the eye. Instead of being tools of humans, the horses are revealed to be intelligent in their own right. In one stroke, they go from being a manifestation of humanity to something utterly nonhuman.
There are a number of differences between the first three voyages and the fourth. Three of these differences are particularly important because they signal changes in the overall satirical thrust of the novel: Gulliver finds himself not among fellow humans, however distorted in size or culture, but among a race of horses; instead of being happy to leave, he is eager to stay; and instead of seeing the world through his eyes, we are forced to step back and look at Gulliver himself as an important, though not always sympathetic, player in the drama.
In other ways, these chapters are similar to the initial chapters of the other voyages. Gulliver arrives in a strange land, becomes the guest or prisoner of the people who live there, learns their language, and slowly begins to learn about their culture and tell them about European culture. The major difference here is that the humans, or Yahoos, are not his hosts. Instead, they are vile creatures that get nothing but his contempt. In his descriptions of the Yahoos, Swift uses the technique of describing the familiar in unfamiliar terms. Only slowly does it dawn on us that the Yahoos are humans. As with the realization that the Houyhnhnms are intelligent in their own right, the sudden shock—which we experience along with Gulliver—of recognizing the Yahoos for what they are strengthens the impact of the description.