Although a chapter on sleep contributes nothing to the Shandy family story, it is valid from the point of view of the author himself: he is writing a book that contains "various things" besides Shandy history. The chapter is outside the Shandy history but inside the "Life and Opinions" framework.
The third accident is revealed to Walter as he discovers that there is no one in his house named "Trismegistus." The author skillfully varies the impact of this latest frustration; it is a grave blow to Walter, but he doesn't comment until several chapters later when he unburdens himself of his lamentation. In the meantime, we remain in suspense, wondering why he doesn't react immediately and what he will do when he does react.
Misunderstanding and faulty communication surge up still again when Trim and Toby discuss the "accident," Trim thinking of the cow and the fortifications, Toby, of the misnaming. We are reminded of the "bridge" of Book 3.
There is nothing but hobby-horses in Chapters 18 and 19: Trim and Toby are caught up by their enthusiasm about how one breaches a fortification, and Walter enters deep in thought about all the awful things that have destroyed the future of his child.
Should we take Tristram seriously when he says that the main purpose of his book is to amuse and cheer up the reader? We can easily believe him, but we should not limit our understanding of it to just that point; here he says only that he is writing against spleen. He is writing it for many other things. The difficulty lies in believing that anyone who can find humor in practically everything can ultimately have serious things to say as well. A serious manner — "gravity" — is "a mysterious carriage of the body to cover the defects of the mind," quotes Tristram earlier (Book 1, Chapter 11). Levity and humor, similarly, may be covering up something too — something other than "defects of the mind," of course.
