Dr Jekyll represents not the pure good, but the whole of a person, and Mr Hyde represents pure evil and contains little of Dr Jekyll in him. Although these two characters stand in stark contrast to one another, it is hard to separate the two apart, what we considered to be the author's intention.
Dr Jekyll and Mr Hyde are dual not only in behaviour but also in stature as well. Dr Jekyll is described as a "smooth faced- tall man, whereas Mr Hyde is perceived to be a man with much smaller stature, a visible hunch and much younger than Dr Jekyll. This stature difference comes to reinforce the idea of Mr Hyde as a part of Dr Jekyll, for the reason that a part must always be smaller than the whole.
In the novel, Dr Jekyll attempts to explain this phenomenon providing "the virtue and control- over his evil side in the past, as the reason for Mr Hyde's "less developed- body.
The theme of duality is also marked by the symbolic nature of the name Hyde. Hyde derives form the more familiar word "EHIDE-. It is considered to be a pun itself, as it is pronounced "hide- which is precisely what he is doing under the veil of respectability, hiding his actions and himself form the society. As Mr Utterson ironically jokes "If he be Mr Hyde I shall be Mr Seek-. .
Also Dr Jekyll's name is symbolic. What the author meant for it, was to be pronounced as if it was French - JE KILL. "Je- in French means "I-, thus Jekyll was hopping to kill off his hidden evil side.
Although a lot more restrained than Dr Jekyll and Mr Hyde, Mr Utterson too has elements of duality within his character. For instance, he quickly becomes obsessed with Mr Hyde, when he is told about him, by Enfield. Another example is when Dr Lanyon is deceased and has left a letter for Mr Utterson "not to be opened until the death or disappearance of Dr Henry Jekyll-, Mr Utterson is tempted to disrespect the prohibition, illustrating the omnipresence of duality within his character.
