Summary
Kidder continues to follow Farmer as he treats the Haitian sick. Farmer tells stories about how one woman's death led him to revise his treatment program, including running an experiment with TB patients. One group received the standard medical treatment. The other group received standard treatments, plus visits from Zammi Lasante workers and stipends to buy better food. Only half of the control group recovered, whereas everyone in the experimental group did. From this, and from discussions with Haitians about their beliefs in sorcery, Farmer concluded he had "to worry more about his patients' material conditions" than what they believed.

Kidder accompanies Farmer as he goes out into the countryside to visit patients. They start in a truck, drive as far as they can, and then walk on. As they travel, the men walk across a dam that is an example of American foreign aid. By blocking the water, it displaced many Haitian farmers who were just getting by. Their homes flooded, so they had to move to poorer ground.

Though he has a slipped disk and a leg injured by an old car wreck, Farmer repeatedly leaves Kidder behind as they walk on, then stops at the top of the next hill to wait for him. They walk, visit patients, and then continue walking, talking about Haitian society, medicine, and international politics as they do so. At their final stop, there is a cockfight. The spectators bring out chairs for Farmer and his "blan" (his white visitor). They visit with the villagers and then walk back.

Analysis
In Chapter 4, Kidder and the reader follow Farmer deeper into Haiti and deeper into Farmer's view of the world. It also reminds the reader of Farmer's education and of the literary construction of the world readers are exploring. This begins with the trope in the chapter's first paragraph of Farmer as Kidder's Virgil in Haiti. By implication, this casts Haiti as hell, and Kidder as Dante—and suggests that while Farmer will remain in Haiti as Virgil remained in the afterlife in Dante's Divine Comedy, Kidder will return to the world of the living/Western civilization, and will carry the story of those suffering in Haiti/hell to that world.

That the book's narrative will be complex, rather than simple, is underscored through the inclusion of the story Farmer tells Kidder about his discussions of sorcery with an older Haitian woman. In that story, the woman indicates that she knows TB is caused by germs—but still claims someone sent her that sickness via sorcery. When Farmer asked why she took her medicine if she believed in sorcery, she says "Cheri…eske-w pa ka kon-prann gaby ki pa semp," meaning "Honey, are you incapable of complexity?" In other words, in Haiti, and in this account, things can have more than one cause and more than one meaning, and people can travel between these frames of reference.