Ironically, it is Mustapha Mond who cites Shakespeare's Caliban from The Tempest, a passage that is one of the most poetic of the play, and recited by the man-monster who seems incapable of such beautiful language.  This recital by the Controller surprises John happily, "I thought nobody knew about that book here, in England." Mustapha Mond explains that the New World has no use for old things.  Besides, he explains, people cannot understand tragedies when they are always kept happy. Mustapha says,

"...you can't make tragedies without social instability.  The world's stable now.  People are happy; they get what they want, and they never want what they can't get.'

Mond mocks John the Savage for talking to the Deltas about liberty. He further explains that in order to have stability, the New World has sacrificed such things as Shakespeare's writings that constitute "high art." Likewise, free choice, a topic about which Shakespeare writes is also dangerous, so it has been sacrificed to genetic stability:  only so many Alphas and more Epsilons.

But, John's having read Shakespeare, whom critic Harold Bloom calls our first psychologist, allows him the understanding that without misery, people can never achieve real happiness;  unending happiness is a way of degrading man.  Mustapha counters, telling John that independence was not made for man; it is an unnatural state.  And, God is not compatible with machinery and scientific medicine and universal happiness, which have become the gods of the New World.

The Savage chooses not to lose control of his life, the right to be unhappy, to experience life deliberately and with honesty.  John the Savage rejects the characters of the Brave New World, choosing to exile himself.