Jack be nimble,
Jack be quick
Jack jump over
What? But why on earth...
Well, in those days (the rhyme was first recorded in the early 19th century) they had, as they say, to make their own entertainment.
Jumping over a candlestick was a game, and also a sort of fortune-telling device. Good luck would be yours, it was said, if you could jump over the candlestick without putting out the candle.
Bad luck was certainly yours if you went and set fire to yourself.
However, Nimble Kate isn't a champion candlestick jumper, but a rather rampant American weed, Sicyos angularis, also known as the Bur Cucumber.
And a nimblewit...well, if you are one yourself then you probably don't need me to tell you that it's an alert and clever person.
Thing To Do Today: be nimble. This word comes from the Old English nymel, meaning capable, which is a sort of mixture of the Old English words nǣmel, quick-grasping and numol, able to take. The Greek word nemein, to take, is also part of the word nimble's history.