Nothing is irreversible until the final act is played out.
This colloquialism means that one should not make assumptions about the outcome of an event which is still in progress. The phrase is most commonly used in association with organized competitions, particularly sports.
The “fat lady” may be the valkyrie Brünnhilde, from Richard Wagner’s Götterdämmerung, the last of the very long operatic Ring Cycle. “When the fat lady sings” is a sensible answer to the question “when will it be over?” That must have been asked many, many times during Ring Cycle performances, since they last nearly 14 hours.
Brünnhilde is traditionally presented as a very buxom lady with horned helmet, spear and round shield. Her aria lasts almost twenty minutes and leads directly to the end of the whole Ring Cycle. As Götterdämmerung is about the end of the world (or at least the world of the Norse gods), her aria really does mean, “it’s all over.”
However, all the early printed references to the phrase come from US sports in the 1970s.
The Dallas Morning News recorded the following conversation on March 10, 1976, in regard to a 72-72 tie in the SWC tournament finals:
“Hey, Ralph,” said Bill Morgan, “this… is going to be a tight one after all.”
“Right,” said Ralph Carpenter, Texas Tech sports information director, “the opera ain’t over until the fat lady sings.”
Bill Morgan vividly remembered the comment and the uproar it caused throughout the press box. He always assumed it was coined on the spot and said it was “vintage Carpenter.”
Another theory which ties the phrase to American sports is that the fat lady was singer Kate Smith, known for her renditions of “God Bless America.” The Philadelphia Flyers hockey team played her recording of the song before a game in December 1969. The team won and they began playing it often, as a good luck token. Smith later sang live at Flyers’ games and they had a long run of good results in games where she did so. However, the claim would only have some validity if Kate Smith sang at the end of the game, rather than at the beginning.
Though there’s no written record of the phrase before the 1970s, some residents of the southern USA claim to have known the phrase all their lives, as far back as the early 20th century. “It ain’t over till the fat lady sings the blues” and “Church ain’t out till the fat lady sings” are versions that have been reported.
My money’s on Brünnhilde. She deserves to be immortalized for the hours of agony she inflicted on people like me, who regard the sound of operatic arias as equivalent to nails scraping across a blackboard.