What is the theme of insanity in general? What does it teach us?
Insanity in The Pearl is linked to ideas of stability and continuity. Despite Kino’s poverty at the story’s outset, we can see that as long as his life remains undisturbed he has a chance at being happy (and sane). Only when his circumstances change drastically does Kino begin to suffer in lasting ways, both from his poverty and from a loss of stability.
Steinbeck scholar Peter Lisca summarizes Kino’s plight succinctly, suggesting that Kino's newfound ambition to send his son to school is accompanied by disaster.
"[Lisca] sees that Kino finds himself possessed of the means to buy into that world but he also finds his house burned down, his wife physically beaten, his only son killed, and the lives of three men on his soul." (qtd. in eNotes)
If sanity is derived from a sense of continuity and stability, we can see quite graphically in the story of Kino what happens when these essential factors are disturbed.
As much as we can agree with Kino’s motivations to raise his family from a poverty that denies them access to schools and basic health care and doctor’s visits, we can see too a commentary on unmooring, uprooting, and divorcing from the past.
There are costs to great change. This may be one of the messages we see in The Pearl, and it is a rather disturbing one given the fact that Kino’s hoped-for change seems so natural and humble.
Sanity then becomes associated with one of the novel’s central conflicts, which is a desire for positive change and the costs that are associated with such change. Does Kino lose himself in his (understandable) desire to raise his family out of poverty? Does he fall into a sort of insanity wherein he is blinded to certain realities, preferring to recognize only the potential for achieving his desires and nothing more? If the answer to these questions is yes, should we then judge Kino or commiserate with him instead?
If this novel plays into Steinbeck's non-teleological bent of his Sea of Cortez period (where the parable of the pearl is first mentioned), we have reason to wonder if the author is suggesting that the attempted leap from one system of thought to another can be seen as a kind of hubris that fails to recognize the natural course of human development.
While this reading presumes a borderline condescension from Steinbeck, it is in keeping with his comments in Sea of Cortez. In that book, Steinbeck rejects teleological thinking (a mode of thought that presumes order and purposeful, conscious directionality) in favor of a view that accepts the natural world as being driven by unconscious systems. In doing so, he suggests at times that the populations he encounters around the Sea of Cortez belong to a world that is different than the one he (Steinbeck) comes from. No "mind" can bridge the gap, it would seem, and so an attempt to straddle these different worlds might lead to insanity.
There is no easy way to square the ethics of a view that suggests people should be accepted as they are (and so also accept for themselves their place in the world) with Steinbeck's view of the desire for change.
If "a dissatisfaction with the status quo of which Steinbeck approves" 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,'” how can we properly resolve the story of Kino's tragedy with this championed view of ambition?
Is Kino insane to try to leave his past behind? Is he denying something essential about his very nature (according to the non-teleological view)? These questions are troubling echoes of the themes in the text.