Initially, he is shocked and somewhat repulsed:
* He remembers Bob as the Soc who attacked him and Johnny. This memory evokes fear and anger within him.
* He sees a stark contrast between Bob's image in the yearbook and the way he remembers him. The yearbook presents a picture of a "perfect" Soc, smiling and seemingly innocent, which clashes with his own experience of Bob as a bully.
He feels a sense of guilt and shame:
* He realizes that Bob was a real person with a life beyond their fight. The picture humanizes Bob, making him seem less like a villain and more like a victim.
* He recognizes that Bob's death had a profound impact on his family and friends. This realization brings about a sense of remorse for Bob's death and his own role in the events leading up to it.
He starts to question his own prejudices and stereotypes:
* Seeing Bob in the yearbook forces Ponyboy to confront the stereotypes he held about Socs. He begins to understand that they are not all rich, spoiled brats, and that some of them are genuinely good people.
* He realizes that his own gang, the Greasers, are also judged based on stereotypes. He acknowledges that they are not all delinquents and that some of them, like Johnny, are actually good-hearted.
He gains a deeper understanding of the tragedy of the situation:
* He recognizes that both Bob and Johnny died needlessly in a fight fueled by gang rivalry and prejudice. This understanding adds another layer of sadness and complexity to the already tragic situation.
In conclusion, seeing Bob Sheldon's picture in the yearbook leads Ponyboy to a deeper understanding of the tragedy that unfolded. It forces him to confront his own prejudices, question his stereotypes, and ultimately gain a more nuanced view of both the Socs and the Greasers. This encounter marks a significant turning point in his journey towards maturity and self-awareness.