How might that statement be relevant to the literary works we’ve studied this term?

This is the question:

André Maurois famously claimed that “’Lost Illusion’ is the undisclosed title of every novel.” How might that statement be relevant to the literary works we’ve studied this term? How does literature explore idealism, the cherishing or pursuit of high or noble principles, purposes, or goals? What does literature have to tell us about the loss of ideals or illusions?and these are the topics we studied this term (Use all three of them):
Lord of the Flies
To Kill a Mockingbird
Macbeth