Houyhnhnms are like ordinary horses, except that they are highly intelligent and deeply wise. Their society is a simple and peaceful one, and they value rationality and truthfulness—they do not even have a word for “lie” in their language. They live in a sort of socialist republic, with the needs of the community put before individual desires. The role they occupy is one of the masters of the Yahoos, the savage humanlike creatures in Houyhnhnmland. Gulliver’s own Houyhnhnm master, the one who first discovers him and takes him into his home, is at first wary of Gulliver’s Yahoolike appearance and hesitant to make contact with him. However, Gulliver’s ability to mimic the Houyhnhnm’s own words persuades the master to protect Gulliver. The master’s domestic cleanliness, propriety, and tranquil reasonableness of speech have an extraordinary impact on Gulliver. It is through this horse that Gulliver is led to reevaluate the differences between humans and beasts and to question humanity’s claims to rationality.
In all, the Houyhnhnms have the greatest impact on Gulliver throughout all his four voyages. He is grieved to leave them, not relieved as he is in leaving the other three lands, and back in England he relates better with his horses than with his human family. The Houyhnhnms thus are a measure of the extent to which Gulliver has become a misanthrope, or “human-hater”; he is certainly, at the end, a horse lover.