Called a “familiar,” from the mediæval superstition that Satan's favourite form was a black cat. Hence “witches” were said to have a cat as their familiar.
Cat. A symbol of liberty. The Roman goddess of Liberty was represented as holding a cup in one hand, a broken sceptre in the other, and with a cat lying at her feet. No animal is so great an enemy to all constraint as a cat.
Cat. Held in veneration by the Egyptians under the name of Ælurus. This deity is represented with a human body and a cat's head. Diodorus tells us that whoever killed a cat, even by accident, was by the Egyptians punished by death. According to Egyptian tradition, Diana assumed the form of a cat, and thus excited the fury of the giants.
The London Review says the Egyptians worshipped the cat as a symbol of the moon, not only because it is more active after sunset, but from the dilation and contraction of its pupil, symbolical of the waxing and waning of the night-goddess. (See Puss.)
Hang me in a bottle like a cat. (Much Ado about Nothing, i. I.) In olden times a cat was for sport enclosed in a bag or leather bottle, and hung to the branch of a tree, as a mark for bowmen to shoot at. Steevens tells us of another sport: “A cat was placed in a soot bag, and hung on a line; the players had to beat out the bottom of the bag without getting besmudged, and he who succeeded in so doing was allowed to hunt the cat afterwards.”
Some ... are mad if they behold a cat. (Merchant of Venice, iv. l.) Henri III. of France swooned if he caught sight of a cat, and Napoleon I. showed a morbid horror of the same; so did one of the Ferdinands, Emperor of Germany. (See Antipathy, page 53; Pig.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894