Tomorrow is another day

Origin

The last line of the American Civil War novel Gone With The Wind:

Scarlett O'Hara: "Tara. Home. I'll go home, and I'll think of some way to get him back. After all, tomorrow is another day"

This joins "Fiddle-dee-dee!" and "Great balls of fire!" as lines spoken by Scarlett O'Hara that have become commonplace in the language.

See also: the List of Proverbs.