Hyde to support the universal theory that all human beings have a natural duality and that there is good and evil in everything. In the critical essay Jekyll and Hyde and the Double Brain of Robert Louis Stevenson, Anne Stiles further criticizes the features of the tale when she presents: "Like these scientists, Stevenson explores the potentially heretical possibility that human beings are intrinsically double, even in a healthy state ". .According to Jekyll's tale, both he and Hyde existed before the discovery of salt which allows them to lead separate lives” (Stiles 4). Jekyll is aware of his desire for evil and is looking for a way to separate good from evil. As drugs ease the pain of addicts, the salt Jekyll adds to the potion relieves the stress of duality in his mind. He abuses his body to escape the chains of his mind and not feel the guilt of wanting to be mischievous. Whether sane or mentally ill, Jekyll is a pronoun example of the inherent duality in human minds. Furthermore, Stevenson incorporates an extension of duality which is good versus evil. In Dr. Jekyll and Mr. Hyde, Thomason reveals: “Stevenson argues that the novel is 'a symbolic representation of the dual nature of man, with the morals reversed: not to impress us with the victory of good or evil, but to warn us of the strength and of the final triumph of evil over good once sin is permitted to enter the human habitation'” (Thomason 9). It is evident that Dr. Jekyll is a prestigious example of the fact that human beings do not know their strength mentally, nor do they know their strength physically. In Jekyll's righteous attempt to separate good from evil, evil prevailed over good. Evil, Edward Hyde, had the greatest victory over good, Henry Jekyll, being fatal to both