All the themes already mentioned will get you on your way to writing a great essay, but also consider the Price of Wisdom.
Juana understands far sooner than Kino the danger in possessing the pearl. “It will destroy us all,” she cries out to him. “Even our son.” After Kino and Juana’s way of life has been obliterated—their house burned and Kino’s canoe smashed—Juan Tomás attempts to save them from further destruction. “There is a devil in this pearl,” he tells Kino. “You should have sold it and passed on the devil. Perhaps you can still sell it and buy peace for yourself.” Kino refuses, clinging to the pearl although he perceives it differently: “I have it … And I will keep it … now it is my misfortune and my life and I will keep it.” When Kino is caught up in dreams of the future, he beats Juana for attempting to throw the pearl into the Gulf; at the conclusion of the story, it is Kino who returns the pearl to the sea. Juana stands beside him, the bloodied body of their dead son wrapped in her shawl—a terrible price to pay for Kino’s acquiring wisdom.
What, however, is the wisdom of The Pearl, if indeed it is a parable? The question remains unanswered in the story, but a passage from the text suggests an interpretation:
For it is said that humans are never satisfied; that you give them one thing and they want something more. And this is said in disparagement, whereas it is one of the greatest talents the species has and one that has made it superior to animals that are satisfied with what they have.
The lesson inherent in Kino’s possessing “the Pearl of the World” may be found in this characteristic of human nature: the desire for more. One of man’s “greatest talents,” the story suggests, is also a curse that creates dissatisfaction and destroys contentment.
Before finding the pearl, Kino lives a peaceful and secure existence, in harmony with the natural world; he finds happiness and fulfillment in the simple routines of his life—waking up beside Juana, listening to “the little splash of morning waves on the beach,” watching Coyotito sleep in his cradle, and standing on the beach before dawn to watch the sun rise out of the Gulf. The morning before Kino finds the pearl is “a morning like other mornings and yet perfect among mornings.” He lives within “the Song of the Family”; it rises sometimes “to an aching chord that caught the throat, saying this is safety, this is warmth, this is the Whole.”
When the pearl comes into his possession, Kino forfeits his old life for new dreams; he gains nothing and loses almost everything of real value. When he and Juana return to their village with Coyotito’s body, they have been transformed by grief and seem “removed from human experience.” The pearl, once luminous and enchanting, now seems ugly and gray to Kino, “like a malignant growth.” Standing at the water’s edge, he flings it into the sea “with all his might.” Readers find many meanings in The Pearl, as Steinbeck intended, but the primary truth of the story seems to be a warning as much as a lesson—to be aware of the human drive to want more than we have and to appreciate and protect what is truly valuable in our lives before it is lost.