Books like Dr. Jekyll & Mr. Hyde

A good man takes a potion that turns him into a freak of pure evil. A reasonable scientist is transformed - through the agency of science itself - into the living embodiment of unreason. Like the vampire and the werewolf, the sundered personae of Dr. Jekyll and Mr. Hyde have worked their way into our collective unconscious, expressing both our ambivalence with science and our deepest questions about what is knowable in human nature.