The "perplexities" that threatened to retard the healing of Uncle Toby's wound consisted of the difficulty of explaining clearly the technical details of where and how he received the wound; he would "oft times puzzle his visiters, and sometimes himself too." He thought of getting a "large map of the fortifications of the town and citadel of Namur." He did so, and that was how his hobby got started.
Tristram thinks about certain objections that will be made by the critics, and he answers their charges. He reaffirms that his book is a history. "Of who? what? where? when?" "It is a history-book, Sir, . . . of what passes in a man's own mind." He cites John Locke's Essay Concerning Human Understanding, pointing out that Locke's interpretations do not apply, and he says that Uncle Toby's "life was put in jeopardy by words," not by ideas.
Toby gets his map and studies it. He learns more and more about fortified towns (like Namur) and begins to study all manner of military writings on military architecture, ballistics, trajectories, projectiles. Tristram fears for his uncle's health, and he urges him — as if he were actually there at that moment — to give it up: "Intricate are the troubles which the pursuit of this bewitching phantom, KNOWLEDGE, will bring upon thee. . . . Fly — fly — fly from it as from a serpent. . . . O my uncle! my uncle Toby!"
Tristram tells why he ended the chapter at the "last spirited apostrophe" (it was for the sake of letting it "cool"). Good writers must consider these matters of emphasis and proportion.
