The Question and Answer section for The History of Rasselas: Prince of Abissinia is a great resource to ask questions, find answers, and discuss the novel.
There are a number of things he learned on his voyage: too many details to put in this short forum space. I suggest that you check out the GradeSaver themes page at the link below. You will find something that he learned under every theme.
Is this related to the work you have cited above?
Rasselas is twenty-six years old; he is the fourth son of the emperor of Egypt. He and other of the family line are kept prisoner in a beautiful valley of Amhara. He has ever wish granted him, is intelligent, well-versed, and wee taken care, but...