" I am reminded,” said the Mouser, “of what a witch told me about adepts. She said that, if an adept chances to die, his soul is reincarnated in a mouse. If, as a mouse, he managed to kill a rat, his soul passes over into a rat. As a rat, he must kill a cat; as a cat, a wolf; as a wolf, a panther; and, as a panther, a man. Then he can recommence his adeptry. Of course, it seldom happens that anyone gets all the way through the sequence and in any case it takes a very long time. Trying to kill a rat is enough to satisfy a mouse with mousedom. "

― Fritz Leiber , Swords in the Mist