In his mind a new song had come, the Song of Evil, the music of the enemy, of any foe of the family, a savage, secret, dangerous melody, and underneath, the Song of the Family cried plaintively. (1.14)
Kino defines as evil anything that threatens the safety of his family.
And the beauty of the pearl, winking and glimmering in the light of the little candle, cozened his brain with its beauty. So lovely it was, so soft, and its own music came from it – its music of promise and delight, its guarantee of the future, of comfort, of security. Its warm lucence promised a poultice against illness and a wall against insult. It closed a door on hunger. And as he stared at it Kino's eyes softened and his face relaxed. He could see the little image of the consecrated candle reflected in the soft surface of the pearl, and he heard again in his ears the lovely music of the undersea, the tone of the diffused green light of the sea bottom. Juana, glancing secretly at him, saw him smile. And because they were in some way one thing and one purpose, she smiled with him.
And they began this day with hope. (3.80 – 3.81)
The pearl is neither evil nor good. It is simply what the characters choose to see.
But Kino's brain burned, even during his sleep, and he dreamed that Coyotito could read, that one of his own people could tell him the truth of things. And in his dream, Coyotito was reading from a book as large as a house, with letters as big as dogs, and the words galloped and played on the book. And then darkness spread over the page, and with the darkness came the music of evil again, and Kino stirred in his sleep; and when he stirred, Juana's eyes opened in the darkness. And then Kino awakened, with the evil music pulsing in him, and he lay in the darkness with his ears alert. (3.70)
That Kino senses evil by hearing a song is a suggestion that he’s operating on intuition, not on conscious thought.
"Hush," said Kino. "Do not speak any more. In the morning we will sell the pearl, and then the evil will be gone, and only the good remain. Now hush, my wife." (3.78)
It’s unclear whether Kino is patronizing his wife by calling the pearl "evil" or whether he truly acknowledges its nature.
Kino knelt beside his wife. "So the doctor knew," he said, but he said it for himself as well as for his wife, for his mind was hard and suspicious and he was remembering the white powder. Juana rocked from side to side and moaned out the little Song of the Family as though it could ward off the danger, and the baby vomited and writhed in her arms. Now uncertainty was in Kino, and the music of evil throbbed in his head and nearly drove out Juana's song. (3.51)
Kino has a keen sense of evil, more so than his wife, who is fooled by the doctor’s dissembling.
Now the tension which had been growing in Juana boiled up to the surface and her lips were thin. "This thing is evil," she cried harshly. "This pearl is like a sin! It will destroy us," and her voice rose shrilly. "Throw it away, Kino. Let us break it between stones. Let us bury it and forget the place. Let us throw it back into the sea. It has brought evil. Kino, my husband, it will destroy us." And in the firelight her lips and her eyes were alive with her fear. (3.75)
Here it is Juana, not Kino, who has the incisive ability to recognize evil.
But Kino had grown tight and hard. He felt the creeping of fate, the circling of wolves, the hover of vultures. He felt the evil coagulating about him, and he was helpless to protect himself. He heard in his ears the evil music. And on the black velvet the great pearl glistened, so that the dealer could not keep his eyes from it. (4.42)
Is the evil music coming from the buyers…or from the pearl?
"Kino, this pearl is evil. Let us destroy it before it destroys us. Let us crush it between two stones. Let us – let us throw it back in the sea where it belongs. Kino, it is evil, it is evil!"
And as she spoke the light came back in Kino's eyes so that they glowed fiercely and his muscles hardened and his will hardened.
"No," he said. "I will fight this thing. I will win over it. We will have our chance." His fist pounded the sleeping mat. "No one shall take our good fortune from us," he said. His eyes softened then and he raised a gentle hand to Juana's shoulder. "Believe me," he said. "I am a man." And his face grew crafty. (4.84 – 4.88)
The word "crafty" is an interesting choice here, since it has not-so-great connotations that one might even call "evil." The pearl is clearly affecting him.
He took his knife and left her. He stumbled toward the beach and he came to his canoe. And when the light broke through again he saw that a great hole had been knocked in the bottom. And a searing rage came to him and gave him strength. Now the darkness was closing in on his family; now the evil music filled the night, hung over the mangroves, skirled in the wave beat. The canoe of his grandfather, plastered over and over, and a splintered hole broken in it. This was an evil beyond thinking. The killing of a man was not so evil as the killing of a boat. For a boat does not have sons, and a boat cannot protect itself, and a wounded boat does not heal. There was sorrow in Kino's rage, but this last thing had tightened him beyond breaking. He was an animal now, for hiding, for attacking, and he lived only to preserve himself and his family. He was not conscious of the pain in his head. He leaped up the beach, through the brush line toward his brush house, and it did not occur to him to take one of the canoes of his neighbors. Never once did the thought enter his head, any more than he could have conceived breaking a boat. (5.15)
The claim that "the killing of a man was not so evil as the killing of a boat" is an attempt to justify Kino’s recent action.
"I was attacked in the dark," said Kino. "And in the fight I have killed a man."
"Who?" asked Juan Tomás quickly.
"I do not know. It is all darkness – all darkness and shape of darkness."
"It is the pearl," said Juan Tomás. "There is a devil in this pearl. You should have sold it and passed on the devil. Perhaps you can still sell it and buy peace for yourself." (5.28 – 5.31)
Everyone except for Kino recognizes the trouble brought on by the pearl.
He looked into his pearl to find his vision. "When we sell it at last, I will have a rifle," he said, and he looked into the shining surface for his rifle, but he saw only a huddled dark body on the ground with shining blood dripping from its throat. And he said quickly, "We will be married in a great church." And in the pearl he saw Juana with her beaten face crawling home through the night. "Our son must learn to read," he said frantically. And there in the pearl Coyotito's face, thick and feverish from the medicine.
And Kino thrust the pearl back into his clothing, and the music of the pearl had become sinister in his ears, and it was interwoven with the music of evil. (6.16 – 6.17)
The pearl isn’t evil itself, as evidenced by the mingling of music here—it is simply made evil by those who desire it.