What is the overall lesson learned in chapter 20 of The Grapes of Wrath?

I think that Ma's words at the end of the chapter might
represent the overall lesson of the chapter.  When Ma tells Tom that “us people will go
on livin’ when all them people is gone,” it is indicative of a couple of things.  The
first is that there are more poor people who are disenfranchised than rich people who
have power.  Ma speaks the basic idea that as things become progressively worse, there
are more who are marginalized.  If these individuals can learn to coalesce, there will
be change and social transformation.  While Tom is frustrated with how the police are
trying to "break them" and "test their decency," this is a realization that Tom is going
to come to later on in the narrative.  Additionally, the idea of people "livin" while
others are "gone" is something that Rose of Sharon is recognizing as Connie leaves the
camp.  Ma's words speak to the idea that there can be a bridging of social reality
whereby individuals recognize the basic humanity in one another because these are the
individuals who "will go on livin."  When the children stare longingly at Ma's stew, and
she recognizes the importance of giving them some, even when it comes at her family's
cost, Ma recognizes the importance of social solidarity.  She understands that the
economic and social conditions are ones where more people like her are becoming more
apparent.  Her desire to start the broadening of social commitment and transformation is
what ends up keeping the family together and a lesson that will inspire Tom at the end
of the narrative.