An epistolary novel is a novel written as a series of documents. The usual form is letters, although diary entries, newspaper clippings and other documents are sometimes used. Recently, electronic "documents" such as recordings and radio, blogs, and e-mails have also come into use. The word is derived from Latin from the Greek word ἐπιστολή epistolē, meaning a letter (see epistle).
The epistolary form can add greater realism to a story, because it mimics the workings of real life. It is thus able to demonstrate differing points of view without recourse to the device of an omniscient narrator.
There are two theories on the genesis of the epistolary novel. The first claims that the genre originated from novels with inserted letters, in which the portion containing the third person narrative in between the letters was gradually reduced. The other theory claims that the epistolary novel arose from miscellanies of letters and poetry: some of the letters were tied together into a (mostly amorous) plot. Both claims have some validity. The first truly epistolary novel, the Spanish "Prison of Love" (Cárcel de amor) (c.1485) by Diego de San Pedro, belongs to a tradition of novels in which a large number of inserted letters already dominated the narrative. Other well-known examples of early epistolary novels are closely related to the tradition of letter-books and miscellanies of letters. Within the successive editions of Edmé Boursault's Letters of Respect, Gratitude and Love (Lettres de respect, d'obligation et d'amour) (1669), a group of letters written to a girl named Babet were expanded and became more and more distinct from the other letters, until it formed a small epistolary novel entitled Letters to Babet (Lettres à Babet). The immensely famous Letters of a Portuguese Nun (Lettres portugaises) (1669) generally attributed to Gabriel-Joseph de La Vergne, comte de Guilleragues, though a small minority still regard Marianna Alcoforado as the author, is claimed to be intended to be part of a miscellany of Guilleragues prose and poetry. The founder of the epistolary novel in English is said by many to be James Howell (1594–1666) with "Familiar Letters" (1645–50), who writes of prison, foreign adventure, and the love of women.