The theme of the double is a constant of the Victorian writers, in particular of those of the second generation and through it they reveal the hypocrisy of their own time.
Even if Mary Shelley didn't live in the Victorian Age, she underlines the duplicity of the same character. In fact Frankenstein and his monster can be considered one person and the same Frankenstein says of his monster that he is "my own spirit". But both Frankenstein and the monster, after his contact with the human society, reveal the two different aspects of the human soul, the good and the evil ones, separated through science.
The theme of the double will be dealt also by Stevenson at the end of the XIX century. In his novel "The strange case of Dr. Jackill and Mr. Hide" the duplicity of the human nature becomes more explicit, in fact the same man, drinking a potion, can make dominant the one or the other disposition of his soul. The theme of the ambivalence is reinforced by the symbolism of Jeckyll's house, whose two façades are symbolically the two opposite sides of the same man: the front of this house, used by the doctor, is fair; while the rear side, used by Hide, is "part of a sinister block of buildings, which showed no windows". Mr Hide is deformed and smaller than Dr Jeckyll and we can interpret it as the evil part is a small part of the human feelings. When Dr Jeckyll becomes Mr Hide, he becomes able to satisfy all his hidden wishes. Originary Dr Jeckyll is a good man and he has faith in progress, but he dares too much. Mr Utterson is the typical mid victorian man and the difference between him and Dr Jeckyll is that the first accepts the compromise, while the second doesn't accept the role imposed by society.
In 1891 Wilde added to the double nature of man the Victorian attempt to hid the corrupted side of one's personalty under the mask of respectability and beauty. "The picture of Dorian Gray" is profoundly allegorical and it is a 19th century version of the myth of th Faust, the story of a man who sells his soul to the devil so that all his desires might be satisfied. In this novel the soul becomes the picture, which records the signs of experience, corruption, horror, concealed under the mask of Dorian timeless beauty. The picture stands for the dark side of Dorian's personality, which he tries to forget by locking the picture in a room. The orrible, corrupting picture could be seen as a symbol of the immorality and bad coscience of the Victorian middle classes, while Dorian's purity and innocence are symbols of the bourgeois hypocrisy