Revising one’s opinion, intentions, or feelings. Although the idea is much older, the precise expression dates from the early nineteenth century and was a cliché by 1900 or so. Groucho Marx poked fun at it in the motion picture Duck Soup (1933); when Mrs. Teasdale says, “He’s had a change of heart,” Groucho, playing the role of Firefly, replies, “A lot of good that’ll do him. He’s still got the same face.”