As its title suggests, the book is ostensibly Tristram's narration of his life story. But it is one of the central jokes of the novel that he cannot explain anything simply, that he must make explanatory diversions to add context and colour to his tale, to the extent that Tristram's own birth is not even reached until Volume III. Consequently, apart from Tristram as narrator, the most familiar and important characters in the book are his father Walter, his mother, his Uncle Toby, Toby's servant Trim, and a supporting cast of popular minor characters, including the chambermaid, Susannah, Doctor Slop, and the parson, Yorick. Most of the action is concerned with domestic upsets or misunderstandings, which find humour in the opposing temperaments of Waltersplenetic, rational, and somewhat sarcasticand Uncle Toby, who is gentle, uncomplicated, and a lover of his fellow man.