In Chapter V, the dream of Kino's being able to educate his son and povide a better life for him has been ruined by Kino's having killed a man:
Now, in an instant, Juana knew that the old life was gone forever....All of the time Juana had been trying to rescue something of the old peace, of the time before the pearl. But now it was gone, and there was no retrieving it....There was nothing to do but save themselves.
Now, in Chapter VI, Kino and his family flee, walking all night. As they continue, Juana worries that the men will follow; Kino tells her that they will try, and if they do, they will take the pearl from him. And Juana says,
"Perhaps the dealers were right and the pearl has no value. Perhaps this has all been an illusion."
Juana understands the terrible cost of Kino's having found the Pearl of the World. For, it is an uncertain world in which they now live. Earlier in the novel, Steinbeck writes, "In this gulf of uncertain light [where] there were more illusions that realities." The dream of a better life for his son has become now only a dream that is dark, with evil hidden around them.
Juana wishes that Kino abandon this dream turned dark; she desires a return to the Song of the Family and the preservation of their former life as she has a strong sense of foreboding; moreover, this former life is all that she has known of security.