What evidence is there that Juana is able to remain sane while Kino is becoming insane?

Steinbeck felt women are more in tune with the natural rhythms of life and nature. Juana knows how greed can take the hold of men's hearts and blind them to what is really important. When Juana tries to rid them of this evil pearl, Kino hits her.

He said, "I am a man," and that meant certain things to Juana. It meant that he was half insane and half god.”