Fielding sets out to define his terms and to differentiate Joseph Andrews from the "productions of romance writers on the one hand, and burlesque writers on the other." He admits that he has included some elements of burlesque in his "comic epic-poem in prose," but excludes them from the sentiments and the characters because burlesque in writing, like "Caricatura" in painting, exhibits "monsters, not men." True comedy, however, finds its source in nature: "life everywhere furnishes an accurate observer with the ridiculous." The source of the true ridiculous is affectation, which can usually be traced to either vanity or hypocrisy. The latter, he points out, is the more striking as it involves a measure of deceit over and above the mere ostentation of vanity. Fielding defends the various vices inserted in his novel because "they are never the principal figure." He closes by emphasizing the character of Parson Adams, "whose goodness of heart" stems from his "perfect simplicity."
As in his later novel, Tom Jones, Fielding provides the reader with a critical framework and a kind of "Bill of Fare to the Feast." The classics are as important to Fielding as they are to Parson Adams, and in constructing the definition of Joseph Andrews as a "comic epic poem in prose," Fielding refers to two works which help explain his own. The reference to the Odyssey prepares the reader for the themes of wandering and faithfulness, but whereas in the Odyssey the much-tried hero is pursued on his homeward travels by Poseidon's wrath, in Fénelon's version in Télémaque (also referred to in the preface), it is Venus who is the vengeful deity. Thus, one is prepared for the pursuit of Joseph by Lady Booby and — in the intervals — by Mrs. Slipslop.
It is vital to appreciate the limited role that Fielding gives to burlesque; he is attempting to describe the real nature of comedy, just as Joseph Andrews will attempt to discover the real nature of everyone and everything. In linking himself with Hogarth, the "comic history" painter whose works are in the "exactest copying of nature," Fielding presents an argument later echoed by Henry James: "The only reason for the existence of a novel is that it does attempt to represent life. When it relinquishes this attempt, the same attempt that we see on the canvas of the painter, it will have arrived at a very strange pass" ("The Art of Fiction," 1884). Fielding also associates himself with Ben Jonson, "who of all men understood the Ridiculous the best," yet, it would be a mistake to view Joseph Andrews as merely a bitter, corrective piece of satire. The final reference to Parson Adams, for example, establishes the sort of unadorned criterion of simplicity against which the vanity and the hypocrisy of most of the other characters will be measured. In addition, Adams' character as a clergyman is important; throughout the novel, Fielding will be leading his readers beyond "vulgar opinion," which establishes the characters of men according to their dress rather than their greater excellencies, to a recognition of the "unaccommodated man" (King Lear) whom Lear described as "the thing itself."
The existence of the preface, the careful definition of terms, the reference to painting and to the "circle of incidents," and the promise of a happy outcome all indicate the extent to which Fielding is in control of his novel. The characters may, like Adams, have a life of their own, but it is the essence of humanity, distilled through Fielding's own vision, which is presented to us: "I describe not men, but manners; not an individual, but a species" (Book III, Chapter 1). Already we are aware of his acute discernments, his breadth of vision, his firm sense of organization, and his belief in the essential goodness of human nature. The vices for which he apologizes in the preface are more than balanced by the character of Adams and by the fact that they are "accidental consequences of some human frailty or foible."