Superstitions, such as a rabbit's foot being considered lucky, grow out of man's attempts to explain the unknown. When man disproves the old belief, and some still cling to the belief, it becomes a superstition, such as in the instant case. In Western Europe, prior to 600 B.C., man considered rabbits to be sacred, because of their belief that spirits inhabited the bodies of animals, and also because of their belief that man directly descended from a select few of these animals.
Later, the ancient European Celts adopted portions of the older belief, that rabbits were sacred, and that spirits inhabited their bodies. The Celts, based upon the fact that these animals spent an inordinate amount of time in their underground burrows, held the belief that the rabbits' bodies were inhabited by numina, underground spirits with whom they communicated at very close proximity!
Another reason the Celts held the rabbit to be sacred, was because of their prowess in the field of reproduction. They believed that the numina intended for rabbits to be put upon pedestals and revered as symbols of procreation, reproduction with a high turnover rate, of health, and of prosperity.
Since the rabbit itself was considered to be lucky, it follows that any of its body parts would also be considered lucky. People selected the rabbit's foot to tote around for good luck, because of its capacity to dry quickly, its small size, and the fact that it made a great key chain!
