Many works of fiction, drama, and poetry exploit false appearances or contrast appearance with reality as a plot device. One of the major reasons is that it is a way of creating suspense. For example, in a classic murder mystery, several suspects claim to be innocent, but in one case the appearance of innocence is false. Unmasking the reality behind appearances drives plots as diverse as Oedipus Rex and Murder on the Orient Express. Some authors also use this device as a way to critique hypocrisy, as did Orwell and Huxley in their futuristic dystopias. The great thinkers of the 19th century, such as Marx (who argued for underlying motives of class struggle), Freud (who argued for the existence of a subconscious) and Darwin (evolution) all portrayed an ultimate reality quite different from what we perceive through our senses in daily life; these discoveries greatly influenced the development of modernism in literature.