You will not improve as a reader if all you read are books that are well withinyour capacity. You must tackle books that are beyond you, or, as we have said, books that are over your head. Only books of that sort will make you stretch your mind. And unless you stretch, you will not learn.
–Mortimer J. Adler and Charles Van Doren, How To Read A Book (New York: Simon & Schuster, 1972), 339.