Gulliver washes ashore on the coast of Lilliput, where he is immediately taken captive by a bunch of tiny people.
Gulliver goes into great detail about the politics, culture, society, language, and customs of the Lilliputian people – he's obviously interested in their lives, without perhaps fully realizing that at least some of his fascination arises from their similarity to his own.
Gulliver becomes shipwrecked yet again, and this time, it's not nearly so good for his self-esteem: he washes ashore in Brobdingnag, where he is the short one, and no one takes him seriously. We realize that neither Gulliver nor England look all that great when viewed from a bigger perspective.
Gulliver meets the Yahoos and is entirely repulsed. Slowly, he comes to realize that he, too, is a Yahoo: he may have better hair and softer skin, but they're all the same beasts underneath. He feels so disgusted that he never wants to leave the service of the Master Horse.
Well, "thrilling escape and return" is how this is supposed to go, according to Christopher Booker. But in Gulliver's Travels, the thrilling escape is more like "miserable exile," and the return is more like "grudgingly escorted back." Gulliver has completely lost his faith in humanity. His only refuge, now that he has returned to England against his will, is to sit in his garden and avoid the company of his own family.