Technically, Kattenstoet means "Festival of the Cats," which sounds delightful. It commemorates, however, the medieval practice of throwing cats from a high belfry tower in the Cloth Hall. This was considered symbolic of banishing evil. Nowadays it is less fatal for felines: a jester tosses plush toy cats from the tower to waiting arms below.
(Associating cats with the evil of the Black Death, of course, may have led to eliminating one of the potential brakes on its spread, because of course cats might have helped keep in line the spread of rodents whose fleas would have carried the disease.)
Cats weren't always disliked: the number of cats in the margin of manuscripts suggest that they were actually quite common in the monasteries where such manuscripts were being created. Cats also appear in many illustrations of domestic scenes, suggesting that they were a common pet.
The Islamic world saw cats as more preferable than "unclean" animals like dogs, probably because cats are seen cleaning themselves daily. Cats were even acceptable in mosques. Their reputation was probably enhanced by Abu Hurairah, a companion of Muhammad, whose name means "father of the kitten." He fed and cared for stray cats at his mosque. Abu Hurairah was not likely his real name, and his attachment to cats was not his most significant feature. I'll tell you more about him tomorrow.