One of the most important and engaging chapters in The Grapes of Wrath so far would have to be Chapter 13 simply because we have the death of Grampa, and are shown how the Joad family reacts to such an event. Where the family came from, when someone died, it was the families job to tend to the dead by prepping them for burial.We see this in Chapter 13. Ma takes time to wash the body of Grampa while the men all dig a grave. The whole family comes together to make sure the man has a peaceful ceremony, even if the conditions are not ideal.
A passage that I liked was Casy explaining that he knew the old man was dying before they left. "No, you couldn' a done nothin'. Your way was fixed an' Grampa didn' have no part in it. He didn' suffer none. Not after fust thing this mornin'. He's jus' stayin' with the lan'. He couln' leave it."
I suppose another theme kicks in with that passage.Old ways die. Things change. Grampa was set to stay on the land, and make like Muley. As far as he was concerned, he was going to die on that land. But the land was dead before the family left (part of the reason the farmers couldn't do their job). The dead land meant the everyone needed to start a new life. Grampa might have figured he was too old to start fresh, and between how he felt, and the heat from laying in the sun, the man didn't have it in him to continue on.