According to Elijah Muhammad, leader of the Black Muslims, about 6,300 years ago everyone was black. But this all changed because of a mad scientist called Yacub on the island of Patmos. Yacub came up with a plan to create white people by a kind of eugenic evolutionary process. The scientist would not allow people to marry unless one of the partners had a lighter skin than the other. After many centuries, the plan resulted in the creation of white devils "with the blue eyes of death." Elijah Muhammad used this myth not only to explain the existence of the various races of men, but also to explain the tendency among African Americans to prefer mates with lighter coloured skin than their own. Eldridge Cleaver refers to this preference as "the Negroes' racial death-wish."