The story
Coined by William Shakespeare in 1623 in "As you Like it," act 2, scene 7: : And so from hour to hour we ripe and ripe, : And then from hour to hour we rot and rot, : And thereby hangs a tale.
Etymology from Wiktionary, CC BY-SA 4.0.
thereby hangs a tale
Today it means: Used to indicate that something requires a long story or explanation to fully understand. Full definition →