Clarence Darrow was an American lawyer and leading member of the American Civil Liberties Union He is remembered for defending teenage thrill killers Leopold and Loeb and defending John T. Scopes in the Scopes Trial (1925). Darrow began his career as a corporate lawyer and soon switched to criminal law. Darrow was an eloquent speaker and often spoke out against the death penalty. Here Darrow presents his ideas on the latest scientific thought and investigation bearing upon the question of human conduct. Darrow says, My main effort is to show that the laws that control human behavior are as fixed and certain as those that control the physical world. In fact, that the manifestations of the mind and the actions of men are a part of the physical world.