Several themes seem to run through Shelley's Frankenstein, some obvious, others subtle. The most widely heralded theme is the idea that ignorance is bliss. In Shelley's time, the power of human reason, through science and technology, challenged many traditional precepts about the world and man's relationship with his creator. Yet at the same time, many questioned these humanist notions, stressing the limits of human capacity. Shelley details this theme in her book, making an allusion to the counter-humanist idea in chapter four when Victor warns Walton not to follow in his footsteps, saying, Learn from me, if not by my precepts, at least by my example, how dangerous is the acquirement of knowledge, and how much happier that man is who believes his native town to be the world, than he who aspires to become greater than his nature will allow. Indeed, to Shelley and many others of her time, some riddles of nature should never be discovered by man. Even the alternate title, The Modern Prometheus, undeniably relates this point. Prometheus, a figure in Greek mythology, took fire from the gods in order to give it to man and consequently suffered eternal punishment. Clearly, Victor Frankenstein is this modern Prometheus-in a way, he stole the idea of creation from God and used it for his own ill-advised purposes.
A second theme stresses the idea of human injustice towards outsiders. Throughout his narrative, the monster laments over man's cruelty to those who are different. Indeed, Frankenstein's monster is an outcast-he doesn't belong in human society. Yet the monster's alienation from society, his unfulfilled desire for a companion with whom to share his life, and his ongoing struggle for revenge, are all shared by his creator. As the story develops, Victor becomes increasingly like his creation. Both live in relative isolation from society, both hate their own miserable lives, and both know suffering. Shelley, through this theme, paints a very bleak portrait of man and his relationship with outsiders, as well as the cruel vengeance of society.
A third, subtler theme, indicts society for its sexist viewpoints. Throughout his narrative, Victor portrays women as weak, suffering, subservient beings who live for and depend on the men in their lives. Surely Shelley experienced this in her own life, though she may or may not have agreed with it. Ironically, the monster-the one who Victor calls a barbarian-has a very progressive notion of the opposite sex. He believes that men and women are largely equal, not being brought up in Frankenstein's pre-feminist culture. The monster's desire for a female companion does not convey a desire to rule over a woman or a belief that a woman should be dependent on him, but it simply shows his need for an equal companion with whom to share his sufferings.