The score so far...

Does anyone know the origin of the "carrot & stick" metaphor?

The score so far is:
CARROT ON A STICK, meaning a fishing-pole device used to trick an equine beast (usually a mule or donkey, on one occasion a Shetland pony) to move forward: ESC, the Little Rascals, Janis Joplin (song lyrics), cartoons we remember vaguely, an online preacher, and ESC's offspring.

CARROT AND STICK, meaning moving the animal (or a stubborn person) forward with reward and/or punishment: Winston Churchill, the Oxford English Dictionary, detective novel writer Dashiell Hammett, Fanny the pony, Gary the Phrase Finder administrator, Bob (a Phrase Finder regular) and ESC's spouse (imagine the fight that caused).