The Canterbury Tales The Manciple's Tale
When Phoebus lived on this earth, he was a lusty bachelor and a fine archer, slaying serpents and singing with great musical harmony. He was the most handsome and chivalrous knight in the kingdom and one day taught his white crow how to speak the language of humans. Phoebus had a wife, whom he loved more dearly than his own life, and guarded her with the greatest protection possible. He knew that he must let a free spirit fly like any other caged animal, but he made sure to keep her closed in and guarded at all times, nonetheless. While Phoebus was absent one day, his wife sent for his substitute, with whom she was having secret affairs. The white crow, enclosed in its cage, watched the whole time, never saying a word, until Phoebus came home. Upon hearing from the crow that his beloved wife was unfaithful, an enraged Phoebus slew his wife with an arrow and then blamed the crow for telling such stories. He cursed the crow to forever be the color of black and to speak never again: "And to the crowe, O false theef, seyde he, / I wol thee quite anon thy false tale; / Thou songe whilom lyk a nyghtngale, / Now shaltow, false theef, thy song forgon, / And eek thy white fetheres everichon." Manciple's Tale, l.188-192
The Manciple then concludes his tale with a moral that one should never tell another that someone has gone to bed with his wife, and that all men should guard their tongues, for one can never retract what has been said. People are slaves to other's words.