Samuel Smiles, a Scottish author, said:

We learn wisdom from failure much more than from success. We often discover what will do, by finding out what will not do; and probably he who never made a mistake never made a discovery.

Kenneth Boulding, an economist and systems scientist, said:

Nothing fails like success because we don't learn from it. We learn only from failure.

Given our schools' dominant emphasis on getting the right answer, I wonder how often students get a chance to actually learn from their failures (as opposed to simply being told that they are unsuccessful or incorrect). I'm guessing probably not enough...