In Book 3, Chapter 1, Fielding intrudes into the narrative of his novel once again. This time, he's here to lavish ironic praise on works of biography as the only real sources of truth in literature.
Notwithstanding the preference which may be vulgarly given to the authority of those romance writers who entitle their books “the History of England, the History of France, of Spain, &c.,” it is most certain that truth is to be found only in the works of those who celebrate the lives of great men, and are commonly called biographer.
The verbal irony of this passage stems from the tension between Fielding's statement and the obvious status of his own novel as a work of fiction. If truth is "only" to be found in biography, then the reader has spent hundreds of pages reading Joseph Andrews for nothing—despite Fielding's profession, throughout the book, that his own novel contains valuable truths for the reader to ascertain. Fielding obviously believes in his own work and in the capacity of fiction to contain valuable pieces of moral advice, and thus the statement above emerges as a prime example of his playful, self-deprecating, and ironic digressions into the nature of his craft.
In Book 4, Chapter 15, Fielding whisks his story toward a triumphant and happy ending. In a moment of particular dramatic irony, Fielding resolves the question of Joseph Andrews's lineage by revealing his strawberry birthmark:
The Pedlar […] asked her if the supposititious Child had no mark on its Breast? To which she answered, ‘Yes, he had as fine a Strawberry as ever grew in a Garden.’ This Joseph acknowledged, and unbuttoning his Coat, at the Intercession of the Company, shewed to them. ‘Well,’ says Gaffar Andrews, who was a comical sly old Fellow, and very likely desired to have no more Children, than he could keep, ‘you have proved, I think, very plainly that this Boy doth not belong to us; but how are you certain that the Girl is ours?’
To the reader, this mark will have been familiar from all the way back in Book 3, Chapter 4, when Mr. Wilson reveals that his lost son would be readily identifiable by the birthmark. While it takes the characters in the novel an excruciating few moments to place the mark and what it means about Joseph Andrews's parentage, the reader can instantly identify Andrews to be Wilson's lost son—guaranteeing a satisfying moment of dramatic irony at the very end of Andrews's adventure. Fielding begins his novel by excusing Andrews's lack of clear ancestry—and insisting that he is a worthwhile subject by his inherent virtue—but nonetheless closes out the narrative by giving Andrews his family back.
