John has no formal education, having learned what he has from his mother, who taught him to read from an old volume of the works of Shakespeare. Therefore, he perceives people and things through the literary lens of Shakespeare's depictions.
In Chapter 9 when John responds to Lenina's invitation to visit her at the rest-house on the reservation, he is disappointed to find Bernard gone. Finally, after waiting for thirty minutes, it occurs to John to peer through the windows. Seeing a green suitcase with the initials L.C. painted on it, John impulsively—like Romeo—breaks the window's glass and enters the room. After looking through her things, he sees her lying on the bed. Gazing with adoration, John's lips whisper lines from Romeo and Juliet, triggered by the sight of a fly. His quote is from Romeo's reflection that a fly can touch Juliet, but he cannot because he is banished—
On the white wonder of dear Juliet's hand, may seize
And steal immortal blessing from her lips,
Who, even in pure and vestal modesty,
Still blush, as thinking their own kisses sin. (3.3.35-38)
Having no real experience, either vicarious or personal, with anyone who looks like Lenina, all John knows to express his feelings are verses from Shakespeare. Like Romeo, he is stunned by the beauty of the woman before him and completely infatuated with her; therefore, it is appropriate that he express himself with lines from Romeo and Juliet. In addition, that John expresses himself so poetically with sixteenth century verse indicates his naïveté, not to mention his anachronistic character in contrast to the inhabitants of the New World.
Several reasons explain why John quotes Romeo and Juliet in Chapter 9. First, the allusion intimates that he and Lenina are doomed, just as Shakespeare's star-crossed lovers. His readings on the Reservation have educated him well, but in the World State, this education will be deemed worthless, even laughable. It is his knowledge of Shakespeare and other things that will make him an outcast in the World State. People are taught only what they need to know to do their jobs. There is no place for the classics like John quotes.
Even Romeo and Juliet seized the opportunity to spend a night together. In this chapter, John has the chance, but still fails to act. He marvels at Lenina's beauty, but chastises himself for the very thought of undressing her. The scene is ironic because Lenina is in no way virginal, although John still cannot overrule his conscious.