The line in question hinges on recognizing an allusion to Shakespeare and understanding the irony of how it’s used. In The Tempest, a character named Miranda utters “O brave new world” as she encounters a new and unfamiliar society with a sense of innocent wonder. Brave New World, Huxley’s title, borrows that exact phrase to point to the same idea—but with a twist. The irony is that what people call a brave new world is actually a carefully controlled, dehumanized society. The veneer of progress, order, and happiness hides manipulation, loss of individuality, and social engineering. So the phrase, which suggests hopeful discovery, is used to critique the superficial optimism of a world that has sacrificed humanity for stability and efficiency. The other lines don’t fit the same way: they come from different plays and convey different themes—life as performance, existential crisis, or bittersweet farewells—whereas the title’s echo is about the gap between appearance and reality in a supposedly wondrous new world.