Part 4 of Gulliver's Travels deals with Gulliver's discovery of a land where horses (Houyhnhnms) are as intelligent as humans, and humans (Yahoos) are as unintelligent as animals. The satire is found in Gulliver's comparisons of the Yahoos to his own human civilization, deciding that the Houyhnhnm culture is superior because of its focus on rational thinking and lack of lying. Swift contrasts the Houyhnhnm prejudices against Yahoos, as well as Gulliver's initial assumption that the Houyhnhnms have human masters, with the very real issue of racial biases and prejudice based entirely on physical differences. The Houyhnhnms represent a non-European race of intelligent creatures, entirely the equal of "civilized" humans, without the drive for war or lying that humans have; meanwhile, the Yahoos, which resemble humans, are no better than animals in their demeanor and intellect. In this manner, Swift shows the fallacy of assuming that other people, regardless of their physical characteristics, are inferior to a culture's accepted norms.