“Good deeds never lose their merit, though mixed with some that are evil.”Miguel de Cervantes · Don Quijote · 1615 · Partea I, capitolul 22
One mistake never erases the merit of good deeds; moral life is a balance, not a single exam grade.
Cervantes rejects the idea that a single mistake wipes out all the good done before. Moral life is not an exam with one final grade, but a ledger where good deeds keep their value independently of the bad ones. The mechanism is fair judgment: to weigh a person only by his faults is as distorted as weighing him only by his merits. A doctor who saved hundreds of lives and erred once does not thereby become a bad man.
Why it matters It helps with forgiveness — of others and of oneself — when guilt or shame threatens to erase everything good.