At the opening of the Chapter, when the police are investigating Hyde's life and deeds, and we hear about the numerous vile practices he has committed, we now realize that during the year that elapses between Chapters 3 and 4, Hyde had apparently practiced every type of vile and violent deed and "had collected a multitude of enemies." This causes Utterson to utter "the death of Sir Danvers was . . . more than paid for by the disappearance of Mr. Hyde." This is not a callous statement when we realize the extreme extent of the evil practiced by Hyde. Utterson is the type who would gladly sacrifice a single life if it insured the riddance of a universal evil which Hyde now appears to be.
It is also symbolic that once Dr. Jekyll has rejected Hyde, Jekyll changes completely. In medical terms, he has purged himself of some deep disease that was eating away at him. With Hyde gone, for some time (Sir Danvers was murdered by Hyde in October, and it is now early January), Jekyll has changed back into his old social self and has been a delightful host. Thus, it is even more puzzling when Jekyll suddenly reverts to his old secretive self. The explanation for this episode is not given until Chapter 10, when Jekyll explains that he was sitting in Regent's Park, when suddenly, to his horror, he became Edward Hyde and found himself clad in the over-sized clothes of Dr. Jekyll. The shock of this transformation occurring without the use of his potion causes the doctor to totally isolate himself.
