In The Outsiders, how and why does Ponyboy's opinion of the socs change by the end of the story?

At the beginning of the story, Ponyboy holds the same opinion of the socs as the rest of the greasers do.  The greasers hate the socs because the socs are rich, always pick on the greasers, and think that they are better than the greasers. 

As the story continues, however, Ponyboy begins to realize that the socs are just people like the greasers are.  The socs may have more money than the greasers, but they are still people who face pain in the same way and who struggle through the problems in life. 

Ponyboy's relationship with Cherry is the catalyst that causes Ponyboy to begin to think about who the socs actually are and to question the purpose of the on-going feud between the greasers and the socs. 

Also, when Johnny kills one of the socs, Pony begins to realize that the socs are just as vulnerable as the greasers are and that they are people just like the greasers.