On the last journey, Gulliver took an adventurous offer as commissioned captain of a merchant ship bound for the western side of South America. The crew suffers fierce storms and many of the sailors perished, and the sailors take over the ship through a mutiny. The sailors were quick to get rid of the captain and at the first island they sail past, they abandoned Gulliver. On the Island, Gulliver is attacked by the unknown and strange beasts called Yahoos, but the beasts are quickly frightened away by two horses. The horses seemed to converse with each other is a language that was unknown to Gulliver. The two horses take Gulliver to a wood dwelling. Inside he meets a horse whom Gulliver perceives as the leader and the leader allowed him to stay at the dwelling. He spends the rest of his three years stay on the island learning the language and describing the human civilization and culture to the Houyhnhnms. These educated horses call themselves Houyhnhnms and they call the beasts that attacked Gulliver, Yahoos. Through these talks Gulliver is edified by the Houyhnhnms? superior rationality. He deduces from one of these talks that two Yahoos had appeared on the island many years before Gulliver. Through succeeding generations these "humans" lost the ability to use reason. Gulliver is able to do infer that these beasts show many similarities to humans. Gulliver is made to leave the island, because he is so similar to the Yahoos.for they alleged that because I had some rudiments of reason, added to the natural pravity of those animals, it was to be feared I might be able to seduce them into the woody and mountainous parts of the country, and bring them in troops by night to destroy the Houyhnhnms cattle, as being naturally of the ravenous kind, and averse from labor. (Swift 508-509) In part IV of Gulliver's Travels, Swift created an island inhabited by two contrasting species. The more advanced and rational Houyhnhnms, are horses whose actions reason governs.