Clearly one of the central themes of this great classic is racial discrimination and how it is overcome. The fact that Philip is stranded on an island with just Timothy to look after and help him forces him to confront his own racist notions that he has received from his parents, in particular his mother, and he emerges from his experience a changed individual who no longer judges someone's character based on the colour of their skin. Note how Philip is presented when he realises his superiority to Timothy:
I felt good. I knew how to do something that Timothy couldn't do. He couldn't spell. I felt superior to Timothy that day, but I let him play his little game, pretending not to know that he really couldn't spell.
However, it is clear that his attitude changes, as we can observe when Timothy is buried by Philip. Of course, being blind means that Philip has been completely dependent on Timothy, which has forced him to re-learn a number of different things, not least how to survive with his new limitations, but also how to value other humans. Let us consider this change in action:
I buried Timothy, placing stones at the head of the grave to mark it. I didn't know what to say over the grave. I said, "Thank you, Timothy," and then turned my face to the sky. I said, "Take care of him, God, he was good to me."
The message of the novel seems to be clear. Philip has been forced to confront and conquer his own racism and sense of superiority, admitting his dependence on Timothy and how Timothy has been the one to look after him but also the one to teach him how to survive. He emerges from the experience a different, and more enlightened, individual.