There are three plays that are alluded to in Brave New World: The Tempest, Romeo and Juliet, and Othello. These plays are the medium through which John the Savage has learned emotion and recognizes emotion and expresses emotion since his mother is handicapped in this area by her biogenetic engineering and the Indian who lives with her is rather unconcerned with him.
When John arrives in the New World, his first thoughts are comparative with those of Miranda from The Tempest who also has no knowledge of the world. When she first sees other people, the men brought to the island by the magic of her father, Miranda exclaims,
How many goodly creatures are there here!
How beauteous mankind is! O brave new world,
That has such people in't (5.1.207-210)
Since these exclamations are identical to John's feelings, he echoes them. Likewise, when he initially perceives Linda, John finds her so beautiful and physically perfect that, like Romeo, he is starstruck:
...and his voice suddenly took on a new resonance, he truned with a proud squaring of the shoulders, a proud, defiant lifting of the chin "to show that I can bear pain without crying out"...he gave a gasp and was silent, gaping. He had seen, for the first time in his life, the face of a girl who cheeks were not the colour of chocolate or dogskin, whose hair was auburn and permanently waved, and whose expression (amazing novelty!) was one of the benevolent interest....The blood rushed up into the young man's face; he dropped his eyes, raised them again for a moment only to find her still smiling at him,...he dropped his eyes, raised them again for a moment only to find her still smiling at him, and was so much overcome that he had to turn away and pretend to be looking very hard at something on the other side of the square.
Like Romeo, he instantly falls in love with the vision of Lenina that he romanticizes. And, like Romeo and Juliet, the relationship between John and Lenina ends tragically as he realizes she is no ideal for him and gives of herself too freely.
When John attends the feelies with Lenina, he is apalled at the violence and animalistic brutality of the show. This action and later his mistreatment by the New World reminds him of the low envy of Iago and the cruelty against him. All that John has experienced and can relate his new feelings to is of Shakespeare.