In some cultures, the foot of a rabbit is carried as an amulet believed to bring good luck. This belief is held by individuals in a great number of places around the world, including Europe, China, Africa, and North and South America. In variations of this superstition, the donor rabbit must possess certain attributes, such as having been killed in a particular place, using a particular method, or by a person possessing particular attributes (e.g., by a cross-eyed man). It has been suggested by Benjamin Radford that the rabbit's foot could be connected to a European good luck charm called the Hand of Glory, a hand cut from a hanged man and then pickled. Humorist R. E. Shay is credited with the witticism, "Depend on the rabbit's foot if you will, but remember it didn't work for the rabbit." In North American culture The belief in North American folklore may originate in the system of folk magic known as "hoodoo". A number of strictures attached to the charm are now observed mostly in the breach, namely that it must be the left hind foot of a rabbit which was shot or otherwise captured in a cemetery. Some sources tell that the rabbit must be taken by the full moon, and others specifying the new moon. Some say instead that the rabbit must be taken on a Friday, or a rainy Friday, or Friday the 13th. Some sources say that the rabbit should be shot with a silver bullet, while others say that the foot must be cut off while the rabbit is still alive. The various rituals suggested by the sources, though they differ widely one from another, share a common element of the uncanny, and the reverse of what is considered good-omened and auspicious. A rabbit is an animal into which shapeshifting witches such as Isobel Gowdie claimed to be able to transform themselves. Witches were said to be active at the times of the full and new moons. These widely varying circumstances may share a common thread of suggestion that the true lucky rabbit's foot is actually cut from a shapeshifted witch. The suggestion that the rabbit's foot is a substitute for a part from a witch's body is corroborated by other folklore from hoodoo. Willie Dixon's song "Hoochie Coochie Man" mentions a "black cat bone" along with his mojo and his John the Conqueror: all are artifacts