From Norton Juster, The Phantom Tollbooth:
“You must never feel badly about making mistakes,” explained Reason quietly, “as long as you take the trouble to learn from them. For you often learn more by being wrong for the right reasons than you do by being right for the wrong reasons.”
“But there’s so much to learn,” [Milo] said with a thoughtful frown.
“Yes, that’s true,” admitted Rhyme; “but it’s not just learning things that’s important. It’s learning what to do with what you learn and learning why you learn things at all that matters…. what you learn today, for no reason at all, will help you discover all the wonderful secrets of tomorrow.”