Utterson senses that Lanyon, however, is not dying of physical decay; it seems as though he is a victim of some "deep-seated terror" within his mind. Utterson cannot help himself; he remarks on how very ill Lanyon looks, and the doctor admits that indeed, he is seriously ill. "I have had a shock," he tells Utterson, and when Utterson mentions their friend Jekyll's similar illness, Lanyon's face changes. He says that he never wishes to see or talk about Dr. Jekyll. He is vehement: He is done with the doctor; from now on, he will regard Jekyll as being already dead.
Utterson protests at such a display of hatred, but Lanyon is firm. He never wants to see Jekyll again. He tells Utterson that perhaps someday Utterson will learn about the "right and wrong of this." The phrase "of this" eludes Utterson; he cannot fathom what Lanyon is referring to, but whatever "this" may be, it is sufficient to cause Lanyon to tell Utterson that if he cannot talk about a subject other than Jekyll, he must leave.
When Utterson returns home, he sits down and writes a letter to Jekyll, asking straightforwardly for an answer about why he and Lanyon have quarreled. The following day, he receives Jekyll's answer. But after reading the doctor's letter, Utterson knows no more than he did formerly.
