From Superstitions by Peter Maining
A black cat crossing your path heads the list as the world's most famous bad luck symbol, although by one of the most striking inconsistencies to be found in the annals of superstition, the reverse is said to be true in the British Isles! The reason for the dislike of the black cat(and it only applies as long as the creature does not have a single white hair on its body) is because its colour is reminiscent of night and the powers of darkness: a sinister looking, nocturnal animal by nature, it has been considered a consort of evil spirits - in particular witches.