If  we are correct in suggesting the epistle in antiquity functioned as a rhetorical device rather than as a purely pragmatic means of communication between parties separated by distance and time, then there must be something inherent in the epistle that lends itself to eliciting a response from the reader. Certainly, if we look at the New Testament even from a general literary perspective, what becomes immediately apparent is the dominance of the epistle as a genre. In fact, the usual literary classification of the New Testament corpus as biography-gospel, history, epistle, and prophesy can be easily reduced to but two basic genres: narration, and epistle. At times, even these blend so that any distinction seemingly becomes more artificial than real. Yet, whether because of the sheer number of epistles in the New Testament corpus, or because of other factors, the dominance of the epistle as literary type is undisputed.

Even so, the presence of the epistolary form clearly goes beyond the parameters of a private letter. In fact, Luke, Acts, and Revelation are all couched as an epistle. Indeed, the opening sentence in both Luke and Acts alike reference the notion of each having been personally addressed to Theophilus with Acts apparently as a sequel of the story began in Luke. Of course, neither Luke nor Acts is an true epistle, yet both contain the equivalent of an epistolary prescript. Revelation likewise opens in a similar manner, but in this instance, the first three chapters seem to function more as a compendium of epistolary prescripts with seven letters written to seven churches. Certainly, the New Testament does contain definitive personal letters with Philemon, Timothy, Titus, and III John all falling into such a category; however, many of the other epistles are not so easily classifiable.

Hebrews, for instance, has the personal ending common to a private letter, but not the opening. Jude, Peter, and James are all tractates addressed to a general audience. An epistle like Philippians may reference an actual historical situation and audience, but assigning a contextual setting for Ephesians simply may not be possible. Yet, the underlying feature common to all of these is that of genre. All are either epistles or cast as one.

Interestingly enough, the same pattern of imitative epistle along side of genuine private letter can be seen in Greco-Roman culture. As in the New Testament, the epistolary structure often subsumes a larger scope of literary forms. The letters of Epicurus, for instance, adopt epistolary form and characteristics, yet function as a summation or epitome of larger technical matters, covering a number of topics ranging from philosophy and ethics to physics and even astronomy. In Letter I, to Herodotus, Epicurus prefaces his tractate-letter as useful for general study:

Since such a course is of service to all who take up natural science, I . . . have prepared for you just such an epitome
(IX, 37).

A number of Epicurus’ epistles seem intended as helpful references for students (Stirewalt, 22). Libraries, after all, were scare in antiquity. Also framed in letter-format are the monographs of Pluturah. In fact, Morelia includes at least four monographs which intersperse narrative along with advice on marriage and other seemingly unrelated anecdotes. With Plutarch the essay does not merely masquerade as epistle, but subsumes other genre forms as well, and in this respect, parallels some of what we find in the writings of the New Testament. Similar to Epirucus, and Plutarch is the Platonic epistolary collection with Letter VII paradoxically writing against the assumption of incontrovertibility in written discourse (343).

Also representative are the epistles of Isocrates, a number of which thematically seem much closer to political writings than personal discourse. In particular, the short Letter II, written to Philip, not only specifically references the Panegyricus, but an oral address as well, the Philippus (413). A similar affinity between epistle and oral address can be seen in the letters of Demosthenes where the style and locutions are more suggestive of oration than private correspondence (Goldstein, 99). Especially telling is the Epistole of Demosthenes, an actual speech later achieving the status of epistle by being published, yet having neither the structure nor the style of a letter. In this instance, the literary characteristics of an epistle are conspicuously absent. As a communicative symbol, the epistolary form furnished an effective medium for discussing a wide range of topics from natural philosophy to natural science, from the abstract of mathematics to the abstract of poetry, and from genuine interaction between people who knew one another to a mimetic interaction between people who did not know each other. Whether the letter was a forgery, written for deceit or gain, or whether the letter was merely a literary device for framing a non-literary topic, whatever the format or purpose, one conclusion stands paramount—— the classical world understood the epistle format as invoking the dynamics of a dialogue, and thereby engaging audience with writer and message.

As noted earlier, the epistle was regarded essentially as written conversation between friends. There is Demetrius’ well-known reference attributed to Artemon that a letter should mimic improvised conversation. To which Demetrius agrees, adding that a letter must be more formal than conversation, and yet still be thought of as sending a gift (223-24). In fact, central to the letter was the notion of friendship:

If anyone should write a letter about problems of logic or natural philosophy, he may indeed write, but he does not write a letter. A letter’s aim is to express friendship briefly, and set out a simple subject in simple terms. (231)

One implication here is that the epistolary format was indeed used for many purpose other than friendship. Yet, what is indisputable here is that as a literary device, the epistle was employed largely because of its inherent association with friendship.

Demetrius, of course, was not alone in seeing the bond between friendship and letter. In one of his letters to Atticus, Cicero warmly comments, “Though I have nothing to say to you, I write all the same, because I feel as though I were talking to you” (12.53). Seneca also uses a similar tone,

I prefer that my letters should be just what my conversation would be if you and I were sitting in one another’s company or taking walks together (Moral Epistles, 75.1-2).

Needless to say, by mentioning such overtures of mutual friendship, the letter thereby conceded the importance of persevering the bond as a locus of shared identity between the writer and reader. However, the letter had to go beyond the immediacy of shared confidences and past memories to that of discussion and request. Though the private letter may have begun with overture or reminders of a common ground, it could not remain there and still be a dialogue, for friends share in one another’s lives and needs.

Yet, as noted earlier, the intrinsic temperament of the private letter frames or grounds all epistolary discourse whether private, literary, or official. Whether the purpose is furthering some philosophical discussion, or announcing the edict of an emperor, the rhetorical aim fundamentally remains the same—— that of evoking a sense of authenticity between writer and reader.

Yet, the question remains as to how epistolary underpinnings of the private letter actually function to secure this sense of authenticity. The element of friendship, of course, is crucial for the personal letter to function as a rhetorical appeal, yet equally vital is the organization of the appeal itself. In fact, the secret of the success of the epistolary form lies literally within the form itself.