In Stienbeck's novel The Grapes of Wrath, most of the characters went through some type of change. Tom Joad affected many different people throughout the whole trip to California. Not only did he change as a result of the long trip, but also he had a major impact on Jim Casy and on the whole Joad family in general. The significance of these changes helped to determine the whole plot of the unfolding story. Tom's influences changed the way the characters felt and acted.
In the beginning of the novel, Tom Joad has just been released from prison for having killed a man. (Here we find him in a proud, non-regretting state of mind.) As he catches up with his family and travels many miles, his attitude changes drastically. Tom realizes the great value of a close family, so he tries to help his family to stay strong and work together to benefit each other. "You got to think about that day, an" then the nex" day, about the ball game Sat"dy." This quote is taken from a point in the story where Ma is unsure of what will become of their future in California. Tom reminds her that she must take things one day at a time. Their future is indefinite and unclear, but with Tom's positive attitude, the emotional stress is somewhat alleviated from everyone.
When Jim Casy first meets Tom Joad, Tom had just been released from prison. Casy used to be the preacher in the town; therefore he is a longtime friend of the Joad family. Casy has been living his life wondering around aimlessly, obtaining food by killing small animals, and living off the land. Tom asks Casy to join him in looking for his family, and on their search they come to be companions. The two find the Joad family, as they are about to depart, and Casy is invited to join the family on their excursion. At various times in the novel, Casy is asked to say a prayer to which his usual response is, "I"m no longer a preacher." Which in itself signifies a change in Casy.