Theme

Brave New World, in it's entirety is involved with various themes. The final three chapters though, focus on religion, or its lack of,government, escape, (physically and mentally), and self-sacrifice.
Chapter 16's main theme is taken from the sentiments of Mustapha Mond. He discusses wiht John the dangers of art and science. His main point being that if a society does not control art and science to work for good of the people, it will work against them.
Huxley portrays Mond as sacrificing his own individuality and freedom for the sake of Utopia. Mond is quoted as saying that "he who makes the laws is free to break them", pointing out although a government may appear to be equal to the people, the reality is, that it may be a facade because, (in Mond's case), he still thinks "unorthodoxy".
Chapter 17's message is much the same as 16's but Mond reminds John that God has also been sacrificed along with art and science. It seems that Huxley is trying to get the point across that in a society where everyone has what they want and never want more, there is no need for "someone" to console with or make requests to. The main theme here is that humans need suffering, as John says; because in Utopia, although they have eliminated God, the people still have the biological need to suffer and be elated. For this reason, the Utopians must partake in monthly doses of Violent Passion Surrogate.
Chapter 18's theme is the battle of the dreamer,(John), with the cut and paste society that is Utopia. John trys to escape compromising with Utopia by purification, but loses this battle against the norm because he ends up giving in to Soma and sex. His suicide symbolizes the destruction of creativity and imagination.