In the 18th century, the full-length fiction novel was still an emerging art form. However, Gulliver's Travels does share some themes with other prominent works of that era, particularly the novel Robinson Crusoe. Swift borrowed the themes of a civilized person marooned on an island, as well as that person's innate lust for adventure, and gave the work his own unique twist; Crusoe's themes of self-reliance and religion became themes of human folly, with a protagonist who spends all of his time being captured by various strange cultures. While Gulliver is brave enough, he is unable to directly affect his own fate, instead constantly reacting to events around him. Where other works have the superior protagonist reshaping the strange into the familiar, Gulliver finds himself adopting other cultures as a matter of course. Another theme is of unexplored places in the world; where Crusoe had cannibals, Gulliver has tiny people, huge people, and flying islands. This focus on the fantastic allowed Swift to satirize elements of British society in an easily-accessible manner.