What point is Swift attempting to make and how does it serve to conclude not just the fourth book, but the entire nov

"Swift's purpose was to stir his readers to view themselves as he viewed humankind, as creatures who were not fulfilling their potential to be truly great but were simply flaunting the trappings of greatness....The form and structure of the whole work enhanced Swift's purpose, as did the specific metaphors in each of the four voyages."