Failing looks bad but provides more information than success. Trying to understand why you got a good grade on a test isn't all that informative because you had to do well on every part of it. But analyzing a bad grade forces you to zero in on what you got wrong. In European military history, the strongest armies have repeatedly turned out to be the ones who lost the previous war, because the defeat inspired them to reorganize and make strategic innovations while the victors remained complacent. A reward forces you inward; a penalty forces you to look at the world more carefully and make changes.
- John Tierney and Roy F. Baumeister in The Power of Bad