The preface itself functions to show the readers what a good storyteller the author is, cleverly inviting them to seek the main body of the book for even better stories. Furthermore, the reader can instantly notice the utter candor of this author who not only admits his dullness at preface-writing, but transcribes an entire conversation to show the development of his thoughts. The reader also learns that there appears no false scholarship in this "profane history" of the famous knight of La Mancha, so that the story must be a truthful one.
Thus by example, as well as by direct explanation, Cervantes sets forth his main qualities as a writer: felicity to natural happenings, realistic detail portrayed as if in a painting, and purposeful writing in order to destroy the pernicious influence of books of chivalry. Besides amusing the reader in his preface, promising him a didactic, truthful history, Cervantes also suggests that Don Quixote is not superficial and that the "judicious" will find much to think about in the course of the reading.
