(The). See how the cat jumps, “which way the wind blows”; which of two alternatives is likely to be the successful one before you give any opinion of its merit or adhesion to it, either moral or otherwise. The allusion is to the game called tip-cat. Before you strike, you must observe which way the “cat” has jumped up.
We are told that our forefathers had a cruel sport, which consisted in placing a cat in a tree as a mark to
shoot at. A wily sportsman would, of course, wait to see which way it jumped before he shot at her. This sort of sport was very like that of hanging two cats by their tails over a rope. (See page 224, Kilkenny Cat.)
He soon saw which way the cat did jump, And his company he offered plump.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Cat Jumps from Fact Monster: