I got thinkin’ how we was holy when we was one thing, an’ mankin’ was holy when it was one thing. An’ it on’y got unholy when one mis’able little fella got the bit in his teeth an’ run off his own way, kickin’ an’ draggin’ an’ fightin’. Fella like that bust the holi-ness. But when they’re all workin’ together, not one fella for another fella, but one fella kind of harnessed to the whole shebang—that’s right, that’s holy.
In Chapter 8, after Tom and Jim Casy arrive at Uncle John’s farm, the family convinces the ex-preacher to say grace over their breakfast. Casy hesitates, but eventually offers these words. They constitute, in short, the philosophy that governs the novel: both Casy and, later, Tom will put this theory into practice by way of a revolutionary fight for the rights of their fellow man—their efforts to organize the migrant workers. In the end, Casy proves willing to lose his life in this struggle, and Tom, picking up where his mentor left off, resolves to unify his soul with the greater soul of humankind.
On a smaller scale, the Joad family also lives up to this philosophy, determinedly cooperating with fellow migrant workers and offering them their services or their food. Ma Joad in particular emphasizes the importance of keeping the family together. She believes deeply in the power of human bonds to provide not only practical benefits but spiritual sustenance.