Gulliver's Travels, by Jonathan Swift, is regarded as one of the greatest satires in modern history. The purpose of the book, although some of his contemporaries didn't realize it, is to ridicule his government, his rulers, and human nature as a whole. His generalization of the human condition doesn't manifest itself completely until Part IV of the book, where the main character, Lemuel Gulliver, finds himself on an island inhabited by two main species - the Houyhnhnms, horse-like animals, and the Yahoos, human-like animals. The difference between this island and reality as we know it is the fact that the Houyhnhnms are intelligent, noble creatures governed wholly by reason, and the Yahoos are naked, dirty humanoids that seem at best, barbaric creatures. The purpose of Part IV is to show the extremities of human nature, and to display both the good and bad qualities through two different examples.

Swift makes the good quality of human nature seem more foreign to the reader by attributing that good quality, reason, to a horse. It also puts the period of Enlightenment in perspective for the reader. The main purpose of Book IV of Gulliver's Travels is to exemplify the two extremes of human nature, as well as show what position on that spectrum we humans should strive to achieve. The 'positive'; extreme Gulliver encounters on his arrival to the island is the Houyhnhnm, a horse ruled by reason.

Gulliver almost immediately admires these creatures as well as everything about them, especially their speech: '... their language approaches nearest to the High Dutch or German, of any I know in Europe, but is much more graceful and significant'; (Swift 189). He tries throughout his visit to become a Houyhnhnm by learning their language, among other things, despite the fact that he looks nothing like them. Many things about their race impress him, especially the fact that there is no word for 'lie'; in their vocabulary. Instead, it is described as, 'the thing which was not'; (Swift 190). The Houyhnhnms seem to take their 'life by reason'; to the extreme: For example, they only marry for the strength of the species by using arranged marriages to yield the best offspring.

They also lack any consciousness for their own death, something that almost seems anomalistic, not noble. 'Philosophers, poets, artists, and scientists have long held that it is man's consciousness of his death, and his complex feelings toward it, that set him apart from other animals'; (Feitlowitz). This seems too inhuman, and it appears that it would be impossible to be that intelligent and noble, yet still disregard the importance of death. Overall, however, Gulliver's view of the Houyhnhnm is a perfectionistic vision of how human nature, for the most part, should be - ruled by reason. The 'negative'; extreme of human nature that Gulliver encounters is the Yahoos. The Yahoos are naked, dirty creatures that physically resemble humans: 'My horror and astonishment are not to be described, when I observed, in this abominable animal, a perfect human figure...

'; (Swift 186). Immediately, Gulliver does not want to be considered one of the Yahoos. He never takes off his clothes to reveal his likeness to the Yahoo body. The Houyhnhnms still regard Gulliver, however, as either a 'noble Yahoo'; or something in between a Yahoo and a Houyhnhnm -- it seems they are unable to decide. At one point, one of the Houyhnhnms describes Gulliver's body to be extremely inefficient: 'That I could not walk with any security, for if either of my hinder feet slipped, I must inevitably fall. He then began to find fault with other parts of my body, the flatness of my face, the prominence of my nose, my eyes placed directly in front, so that I could not look on either side without turning my head...

'; (Swift 195). The Houyhnhnm even goes as far as to give examples of how even the Yahoo has certain physical traits that better those of Gulliver. This conversation takes a direct shot at the period of Enlightenment, when humans had great regard for themselves, their bodies, their minds, and their accomplishments. (Feitlowitz). Later, Gulliver goes on to describe many things about humans in a greatly negative light. For example, the petty and barbaric reasons for war, the immoral ways people attempt to gain money, and how lawyers are hired to prove 'that white is black, and black is white'; (Swift 201).

By describing the humans in this way, Gulliver makes this extreme of human nature resemble barbaric animals that are governed by appetite and desire, rather than reason. The purpose for comparing these two extremes is to show an ideal for the human race. Swift does not think that humans should be governed by reason and reason alone, however. It shouldn't get to a point where the society is so 'perfect'; that there are no words for lying or evil. Obviously, he feels they should be ruled by more reason than the Yahoos are. A professor from Brown University explains, 'The satire in Book IV is darker and more savage: as an evaluation of the human condition, it frightened the wits out of most of the most eminent Victorians, and remains profoundly disturbing today.

It suggests that the aspects of our lives of which we are most proud are merely slightly more complex versions of the activities which, when they are engaged in by Yahoos, we recognize as being foul, brutal, and disgusting'; (brown. edu). Swift makes it obvious that humans should strive to be nothing like the Yahoos. Although Gulliver seems to idolize the Houyhnhnms, Swift makes hints that some things ruled by reason, such as the practice of marrying for race advancement or the disregard for death, become too inhuman. Swift does this by showing that Gulliver becomes mad by the end of the story, which, in turn, lessens his credibility. For example, despite the fact that Gulliver seems to highly regard the Houyhnhnms in everything, including the aforementioned extremes of their rationality, he later becomes disgusted with his own family and overlooks the impeccable treatment he receives after getting picked up at sea.

'[The captain] desired to know what I would eat or drink; said I should be used as well as himself, and spoke so many obliging things, that I wondered to find such civilities from a Yahoo. However, I remained silent and sullen; I was ready to faint at the very smell of him and his men'; (Swift 231). Despite a great example of a positive attribute of human nature, Gulliver still finds his benefactors vile and disgusting. This is an unfair judgment, and shows that Gulliver is not in his right mind, and therefore, should not be trusted in his assessment of the Houyhnhnms as perfect creatures that live in a perfect society. Through this mental degeneration of Gulliver, Swift is showing that although reason is a good quality for human nature to possess, it should not be taken to an extreme, nor should it be the only governing principle of a society. Swift would like to see human nature ruled by reason for the most part (as the Houyhnhnms are), but with a slight essence of Yahoo traits as well.

Swift succeeds in showing the flaws of human nature through a microscope in Gulliver's Travels. His two extremes yield a greatly exaggerated view of mankind's faults. The entire book Gulliver's Travels has a natural progression heading towards Swift's main goal, which is to show the flaws of human nature as a whole. Swift does not have a grim view of human nature, nor is he a misanthrope as some people suggest. He is merely attempting to show the flaws of mankind, and in order to achieve that, he must exaggerate those flaws greatly to make them obvious. Swift is simply trying to set a goal that all mankind should attempt to meet in order to become, in his opinion, more ideal..