Driven by restlessness, Gulliver sets out on another sea voyage. They land in an unknown country to replenish their store of fresh water. Gulliver walks off alone in search of water, and sees that the rest of the crew are rowing for their lives back to the ship, and huge creature is walking after them. Gulliver runs in the opposite direction. He finds that everything - the hedges, corn, and stiles - is huge. Then he notices some gigantic men carrying reaping hooks. They are about the height of an English church steeple. Gulliver reaches a part of the field where the corn has been laid flat by wind and rain, and finds he cannot make his way through it. He hears the reapers approaching, and fears that he will be killed. He reflects that he is as powerless in this land as he was powerful in Lilliput, simply because of his relative size.
Just as one of the reapers is about to crush him, Gulliver alerts him to his presence by screaming. The man picks him up and takes him to his master, a farmer. The farmer shows Gulliver to his wife, who screams. Gradually, however, she grows very fond of him. They give Gulliver dinner. The farmer's son picks him up by the legs and holds him high in the air, but his father snatches Gulliver from his grasp. The baby of the family treats Gulliver as a plaything and puts him in his mouth before letting him drop, and he is only saved from a broken neck by the farmer's wife. The baby's wet-nurse has to quiet the baby by suckling him. Gulliver describes with disgust the huge size of the nurse's breast.
After dinner, Gulliver is put to bed by the farmer's wife. He needs to relieve himself, but when he gets out of the bed, he is attacked by two rats, and kills one. When the farmer's wife returns, he manages to make her aware of his need to relieve himself, and she takes him out to the garden to do so.
Gulliver is befriended by the farmer's daughter, whom he calls Glumdalclitch, or "little nurse." She names him Grildrig. Gulliver explains that he owes his survival in Brobdingnag to her, but fears that he was the instrument of her disgrace. News soon spreads that the farmer has found a strange creature in his field. One of the farmer's friends comes to see Gulliver and advises the farmer to make some money by exhibiting him on a market day. Glumdalclitch is deeply ashamed of her father's plan, though Gulliver is more philosophical, since even the King of Great Britain, in his situation, would undergo the same treatment.
The farmer puts Gulliver in a box and carries him to the market, where people pay to see him perform. A boy throws a hazelnut at him, and it is so big that it narrowly misses killing him. Gulliver has to entertain spectators for eight hours, and as the farmer continues to exhibit him at his home, he becomes exhausted. Finding that he can make a large profit out of Gulliver, the farmer decides to exhibit Gulliver all over the country, and sets off on a tour with him. Glumdalclitch accompanies them and does her best to keep Gulliver comfortable.
The more money the farmer makes out of Gulliver, the greedier he gets and the harder he pushes him, until Gulliver is reduced to little more than a skeleton. The farmer calculates that Gulliver will die soon and is the more determined to make as much profit as possible before that happens.
One day, a courtier arrives and orders the farmer to take Gulliver to court for the amusement of the Queen. The Queen takes a liking to Gulliver and buys him from the farmer for a thousand gold pieces. Gulliver requests that Glumdalclitch might be admitted into the Queen's service, and that she can continue to look after him. The Queen agrees. The King invites three scholars to work out exactly what kind of creature Gulliver is. After much debate, they can only conclude that he is a "lusus naturae," or joke of nature. When Gulliver explains to the scholars that he come from a land where there are many others like him, and where everything is in proportion, they smile contemptuously and do not believe him. The King, however, is more intelligent than the scholars, and after questioning the farmer, is inclined to believe Gulliver. The Queen has a house and clothes made for him, and becomes so attached to him that she cannot dine without him.
The King questions Gulliver about the religion, politics, and laws of Europe, and Gulliver explains as well as he can, including giving an account of the schisms in religion and the state. The King laughs and reflects on the ridiculousness of human vanity and pride, which is so potent a force even among people of Gulliver's size, who are to Brobdingnagians as small and as insignificant as insects. Gulliver admits that after spending some time amid people of such great size, he himself would be amused to see a group of English lords and ladies, strutting about in their finery. He even thinks that he himself looks ridiculous when place next to the Queen, so small is he.
The Queen's dwarf takes a malicious delight in finding someone smaller than himself to bully, and drops Gulliver in a bowl of cream. He is saved by Glumdalclitch.
Gulliver is much bothered by flies, which leave behind piles of excrement that are obvious to him, though the Brobdingnagians cannot see them.
"I reflected what a mortification it must prove to me to appear as inconsiderable in this nation as one single Lilliputian would be among us." (Part II, Chapter I)
Relative size and significance is a major satirical theme of Gulliver's Travels. Size confers power, so while Gulliver is powerful in Lilliput, he is utterly powerless in Brobdingnag. Without the benefit of such a comparison, however, it is easy for a race or nation to delude itself about how much power and significance it has. The Lilliputians are in the habit of thinking of themselves as very important, though Gulliver could easily crush them. Swift's satirical point is that however important or powerful any group of human beings believes itself to be - including his own contemporaries - they are insignificant in the greater scheme of things, as the arrival of any person or force stronger than them will show. Power is shown to be relative and contingent upon circumstances. This theme is a well-aimed cautionary message to Swift's English contemporaries. England had joined with Scotland in 1707 to form the new state of Great Britain. The new kingdom was the major power in Europe, due to its success in trade, its military capability, and the size of its fleet. It treated the rest of the world with an arrogance corresponding to its strength. That Swift's sympathies lay not with the great power but with the victims of power is clear throughout Gulliver's Travels.
In Chapter III, Swift warns of the insubstantial and relative nature of power through his mouthpiece, the King of Brobdingnag. After Gulliver explains to him about the schisms in European religion and politics, "he observed how contemptible a thing was human grandeur, which could be mimicked by such diminutive insects as I." The conservative Gulliver is predictably embarrassed to hear "our noble country, the mistress of arts and arms, the scourge of France, the arbitress of Europe, the seat of virtue, piety, honour, and truth, the pride and envy of the world, so contemptuously treated," but the reader cannot miss Swift's point, which is to puncture the vanity and pride of the puffed-up, arrogant English and Europeans.
Brobdingnag gives Gulliver ample range to convey his disgust at the functions and appearance of the human body when seen in magnified scale. In Chapter I, Gulliver is repulsed by the sight of the vast breast of the wet-nurse who looks after the baby. The sight makes Gulliver reflect that female bodies only appear beautiful because people cannot see them in such detail. The effect of such observations is to banish human vanity. They also make the point that anything, when examined in close enough detail, reveals imperfections that may not be visible to man's imperfect senses. Swift lived in an age that was making rapid advances in microscopy, and books were being published with illustrations of insects, organisms, and other substances that had never been seen in such detail before.
Despite Gulliver's disgust at the magnified human functions of the Brobdingnagians, their large size reflects their moral stature, which is greater than Gulliver's. Gulliver lies to the king of Brobdingnag out of pride, in order to make England seem better than it is; he is a hypocrite. Most Brobdingnagians are honest people, and this honesty is enshrined in their leadership and government. This is in contrast with England, where the worst vices of the people are built into the government. The Brobdingnagians' morality is also seen in the fact that they do not use their size to exploit and destroy smaller and weaker people. An exception is the farmer, who is prepared to let Gulliver die to make him more profit. This episode is one of Swift's frequent pleas for compassion for the underdog. As a native of Ireland, which for centuries was under the domination of England and later Great Britian, Swift was acutely conscious of the tendency of powerful peoples to oppress the less powerful. Clearly, there can be no more effective way to teach the powerful compassion and humility than for them to spend some time as the underdog, as Gulliver does in Brobdingnag.
Swift targets the pretensions of supposedly learned scholars in the characters of the three scholars who debate as to what sort of creature he could be. They are determined not to believe the most convenient source of information about him, which is Gulliver himself.
The best idea that they can come up with is that he is one of nature's jokes. On one level, this reveals Swift's conviction of the stupidity of some highly educated people. But on another level, Swift is suggesting that the whole of humanity is one of nature's jokes. Gulliver and people of his size may be tempted to view the relatively tiny Lilliputians as nature's jokes, but then in Brobdingnag, it is Gulliver and his race who are the joke. Somewhere else again, it is possible that the huge Brobdingnagians may meet a race of beings who dwarf them, who treat them as insignificant little insects, and who conclude that they are nature's jokes.