How did Tom Joad change in The Grapes of Wrath?

In the beginning, he just wants to be part of the people. He thinks any sort of structure is bad (organized religiom, banks, gov. etc.). However, as he travels with the Joad family, he gets closer to the general population and realizes the potential of them. When he kicks down the cop, it's his way of showing he will do anything for the people and takes the fall for Tom. When in prison, he learns that the people together have more power and can create change. This attitude brings him to being the leader of the strike. He will only take change as a result and anything less would not be accepted. In a way, he knew that he would die for the cause of the people. And he does.