After Lanyon witnesses his transformation, Jekyll shuts the door to many of his close friends, including Utterson. In a letter of explanation, Jekyll employs hyperbole to explain the gravity of his situation to Utterson:
If I am the chief of sinners, I am the chief of sufferers also. I could not think that this earth contained a place for sufferings and terrors so unmanning; and you can do but one thing, Utterson, to lighten this suffering, and that is to respect my silence.
There are two instances of hyperbole in this excerpt. The first is in Jekyll’s self-description (as both the “chief of sinners” as well as the “chief of sufferers”), and the second is in his depiction of his private struggles (“sufferings and terrors so unmanning”). These two examples of hyperbole inspire in Utterson a sense of pity for Jekyll, ultimately manipulating him into dropping his investigation into Hyde’s behavior.
Notice how Jekyll’s language anticipates possible allegations of wrongdoing in the first sentence. He preemptively, however conditionally, labels himself the “chief” of sinners. Jekyll further suggests that whatever he may have done wrong, he is already being punished for it by the suffering he has called down on himself through his actions.
This sentence already openly acknowledges that there is a problem with Jekyll’s behavior, and it tacitly suggests resolution through the course Jekyll has taken (namely, isolating himself and suffering in silence). The closed circle of action and consequence, it is implied, does not require any further investigation or outside involvement. The mystery implicit in the letter’s claim that Jekyll is suffering terribly, without offering any clear cause, increases the story’s sense of drama and the stakes of Utterson’s investigation.
In his statement that he could not previously imagine sufferings “so unmanning,” Jekyll plays on Utterson’s sense of pity; he exaggerates his own suffering and then suggests that the only way Utterson can lessen it is by looking away (“respect my silence”). Undoubtedly, Jekyll’s situation is difficult and unusual, but this description serves less to capture that than it does to dissuade Utterson from examining connections between Hyde and Jekyll after the murder of Carew, for which there would be serious legal consequences.