What are the motifs in The Greatest Miracle in the World by Og Mandino?

Knowledge is a recurring idea in the story. Simon was a very knowledgeable man, able to quote passages from a variety of books at the drop of a hat. Og was able to do the same, but he still learned a lot from Simon. Simon was able to teach Og about the ills of modern society, about the unique problems associated with mankind's lack of self-esteem, and how he believed they could change these problems. Through Simon, knowledge was a wonderful thing, an opportunity for Og to broaden his horizons and see the world in a way he had not before. Simon too used knowledge and the things that Og told him to enrich his life, to grow and to make his existence more rewarding.