Love, it has been said, flows downward. The love of parents for their children has always been far more powerful than that of children for their parents; and who among the sons of men ever loved God with a thousandth part of the love which God has manifested to us?
If you were a medieval scholar reading a book, you knew that there was a reasonable likelihood you'd never see that particular text again, and so a high premium was placed on remembering what you read. You couldn't just pull a book off the shelf to consult it for a quote or an idea.