the Grapes of Wrath

Read the following extract and answer the questions that follow. (50 words)
Wherever they’s a fight so hungry people can eat, I’ll be there. Wherever they’s a cop beatin’ up a guy, I’ll be there. If Casy knowed, why, I’ll be in the way guys yell when they’re mad an’—I’ll be in the way kids laugh when they’re hungry n’ they know supper’s ready. An’ when our folks eat the stuff they raise an’ live in the houses they build—why, I’ll be there. See? God, I’m talkin’ like Casy. Comes of thinkin’ about him so much. Seems like I can see him sometimes.
1. What is the main idea of the text?
2. How important is it for the whole novel?
3. What does it tell us about Tom?