Part IV opens with a series of letters to and from Dr. Jordan. One letter from his mother, Mrs. Jordan, expresses her concern about Dr. Jordan’s choice of career and her desire for him to get married. In a letter to a colleague, Dr. Jordan outlines his theory of the mind as “a terra incognita”—that is, unexplored territory. In a letter that appears later in Part IV, Dr. Samuel Bannerling, the former head physician at the Lunatic Asylum, warns Dr. Jordan that Grace is an inveterate liar.
The narrative shifts to a section written in the third person and focusing on Dr. Jordan. The narrator tells of Dr. Jordan’s medical studies as well as his father’s sudden death. The collapse of his father’s previously successful textile mill has made Dr. Jordan’s plan to build his own asylum feel like “a pipe dream.”
Dr. Jordan is currently lodging in a room in the home of Major C. D. Humphrey. Sitting at his desk, he recalls that when he first saw Grace in the corner of her cell, she appeared to him much like the hysterics he had seen in European asylums. But when she stepped out of the corner, she suddenly appeared quite different, standing tall and self-possessed and with no hint of lunacy. Dr. Jordan realized that he’d indulged in a fantasy, and he reminded himself to maintain his objectivity.
The servant Dora comes into his room to deliver his breakfast. An image comes to Dr. Jordan’s mind involuntarily. In this image Dora is strung up like a pig in a butcher shop, and she looks like a sugared ham. He thinks about his own association of ideas: “Dora—Pig—Ham.” He reflects that the middle term is essential for making the leap from the first to the third, and he theorizes that a lunatic is a person whose chain of associations skips the middle term.
The narrative shifts back to Grace’s first-person point of view. Having just been escorted by two prison keepers who accosted her with unwelcome jokes and sexual innuendo, Grace is now sitting in the sewing room at the Governor’s house, where Dr. Jordan has arranged to meet her in the afternoons. At first she feels like all her time alone in prison has made her forget how to speak. When Dr. Jordan asks questions and writes down her answers, the scenario recalls her time in the courtroom, when her every word was recorded and turned against her. Now, however, she feels that every answer she gives Dr. Jordan is right, as long as she keeps talking.
On another day, Dr. Jordan goes to meet Reverend Enoch Verringer, who hopes to convince the young doctor to contribute to a petition aimed at freeing Grace from prison, should his work with Grace prove her innocence. Dr. Jordan tentatively agrees, and the men discuss the tensions between science and religion, as well as the difficulty of establishing the facts of Grace’s case. Reverend Verringer also expresses his theory that Warden Smith sexually abused Grace, and this abuse pushed her into the brief spell of madness that got her sent to the Lunatic Asylum shortly after she went to prison.