In addition to those main themes noted in other educators' responses, another main idea is the notion that people are different and that one should not judge people based simply on appearances and should instead make allowance for the many differences between people. For instance, when Gulliver first sets out on his travels, he lands in Lilliput and meets the people of Lilliput: the Lilliputians. Lilliputians are tiny in stature but nevertheless are an industrious group who work together to accomplish tasks that seem beyond their capability—almost like ants in an ant colony.
For instance, despite their miniature size, while Gulliver sleeps after coming ashore at Lilliput, the Lilliputian people are able to bind him to the ground. Essentially, they overpower him by working together. He awakes to discover that his arms and legs were “strongly fastened on each side to the ground,” held down by “slender ligatures.” His encounter with the Lilliputians shows the danger of judging people in advance based on their appearance, and it also shows the benefits of community. While one Lilliputian might have no power against him, as a society they are able to dominate him. Both Gulliver and the Lilliputians judge one another by first appearances are are wrong in their initial assessments.
For instance, the Lilliputians not surprisingly are fearful of Gulliver when they first find. After all, they are no larger than six inches tall, and he towers over them when he stands. Therefore, they tie him up so that he cannot hurt them. However, once they begin a dialogue with him, they come to see him as a friend initially and welcome him into their society until they ultimately turn against him. This shows that people should not judge others based on initial appearances.
Moreover, when Gulliver meets the giant-sized Brobdingnagians, they view him as a freak even though it is Gulliver who is normal-sized according to his/our world view. Similarly, when Gulliver meets the Houyhnhnms, they view creatures who are like Gulliver as savages based primarily on appearances.