Quotes Uncovered: When Is It Over?

I’m back to inviting readers to submit quotations whose origins they want me to try to trace, using my book, The Yale Book of Quotations, and my more recent research.
Ken Hirsch commented:

“Try, try, try again” comes from the song “Perseverance; or Try Again” which appeared in William Edward Hickson‘s 1836 book The Singing Master.
You can see the full lyrics in this 1837 journal.

Thanks, Ken! This is a nice improvement on the citation I have in The Yale Book of Quotations.
Alan J. Barnes asked:

Can you trace the origins of “It’s not over until the Fat Lady sings.”?

The YBQ, which attempts to trace the origins of all famous quotations, has this entry:

The opera ain’t over until the fat lady sings.
Ralph Carpenter, Quoted in Dallas Morning News, Mar. 10, 1976. Carpenter was sports information director at Texas Tech University when he uttered this line during a basketball game with Texas A&M. Sportscaster Dan Cook used the expression in a television broadcast, May 10, 1978, before a Washington Bullets – San Antonio Spurs playoff basketball game (Cook has usually been credited as the originator). “The fat lady” was then picked up and popularized by Washington coach Dick Motta. However, a 1976 booklet, Southern Words and Sayings by Fabia Rue Smith and Charles Rayford Smith, includes the saying “Church ain’t out ’till the fat lady sings,” suggesting an ultimate origin in Southern proverbial lore. Ralph Keyes, Nice Guys Finish Seventh (1992), records the recollections of several Southerners remembering similar phrases used as early as the 1950s.”

Do any readers have any other quotations whose origins they would like me to attempt to trace?