A decision was wise, even though it led to disastrous consequences, if the evidence at hand indicated it was the best one to make; and a decision was foolish, even though it led to the happiest possible consequences, if it was unreasonable to expect those consequences.
-- Herodotus
The problem with that quote is that human biases often go the other way, i.e., we'd rather blame bad consequences on bad luck then admit we made a bad decision.
Here's the new thread for posting quotes, with the usual rules: