M. Tullius Cicero is the earliest author of the group (106-43 BC), whose extant 914 letters have all been assessed for the creation of the database. This represents perhaps about half of those published soon after Cicero's death and well known in Antiquity. The precise level of editorial interference, by whom and when, remains unclear. Around ninety of the letters are by correspondents other than Cicero and the texts are traditionally split as follows: Ad Atticum (426 letters dating to 68-44 BC), Ad familiares (435 letters, 62-43 BC), Ad Quintum fratrem (27 letters, 59-54 BC) and Ad Brutum (26 letters from 43 BC; for the debate on their authenticity, see Shackleton-Bailey 1980 10–14). These letters are an unrivalled resource for constructing the life and attitudes of a key player in the Late Republic and his complex negotiations with his peers. Cicero's letters were highly influential in Antiquity, cited repeatedly as the model of epistolary style.
C. Plinius Caecilius, Pliny the Younger, a wealthy landowner, lawyer, statesman and administrator, lived c. AD 61-112. The bulk of his letters were published by Pliny during his lifetime, perhaps from AD 104/105 onwards, with the exception of the over 120 in Book 10, which give the impression of less polish. The collection consists of around 370 letters divided into 10 books, all written by Pliny, with the exception of the final book, arguably the most famous, which presents correspondence between Trajan (50 letters) and Pliny (73 letters). Again these letters provide a fascinating insight into the workings of the centre of power and the broader elite world. Pliny explicitly discusses the importance of Cicero as a letter-writer, referring to an exhortation by Sabinus for Pliny to follow his model (Epistles 9.2).
Gaius Suetonius Tranquillus (c. AD 69-after AD 122), son of a Roman eques, served in the imperial administrations of Trajan and Hadrian. He published a series of works, predominantly biographies, in both Latin and Greek. Many of these are now lost: only De vita Caesarum remains almost fully extant together with fragments of De viris illlustribus, which include extracts of De grammaticis, De rhetoribus, De historiciis (of which a brief life of Pliny the Elder survives), De poetis (of which the life of Vergil and fragments of the lives of Terence, Horace, Lucan, Persius and Tibullus survive) and De oratoribus (of which a brief life of Passienus Crispus survives). He was Trajan's A studiis (an advisor on matters of law and governance), and was later appointed as Hadrian's Ab epistulis (director of the imperial secretariat). Relations with Hadrian, however, seem to have deteriorated and he was dismissed probably in AD 121 or 122. The last reference to him comes from AD 121, but given his publication history it is likely that he lived considerably longer, perhaps into the reign of Antoninus Pius. Alongside a wide range of other evidence for code-switching, examples of epistolary code-switching can be found in letters between Suetonius and Pliny the Younger and in excerpts of Augustus's letters cited by Suetonius, about whose authenticity and Suetonius's means of access, perhaps via the imperial archives, there has been extensive debate.
M. Cornelius Fronto (c. AD 90/95-167) was born in Cirta, Roman Numidia (modern Constantine, Algeria), the descendant of apparently wealthy Roman colonists, and became a leading advocate at Rome and a teacher of literary criticism and rhetoric. By the 120s he was a senator and in 142 consul suffectus. He became Marcus Aurelius's Latin teacher in 139, at the instigation of Antoninus Pius, and continued until Marcus became co-regent and focused his attention on other studies in around 145. The bulk of Fronto's correspondence is between Marcus Aurelius and Fronto: over 170 of the 232 extant letters result from this epistolary relationship. There are also letters to and from Lucius Verus, Antoninus Pius and a range of slightly less towering figures. The letters were perhaps not edited until the fourth century (Charisius and Sidonius Apollinaris attest to their later popularity), and they were probably not prepared for publication by Fronto. The text of Fronto's correspondence is extremely problematic: not only are we missing probably more than half of the whole as it existed in the fifth century, but ‘to Fronto belongs the unique distinction of surviving in no fewer than three palimpsests' (Reynolds 1983 173) which has made establishing the text challenging. Fronto and Marcus Aurelius both explicitly use Cicero as a model for letter-writing but Pliny is not mentioned in the extant letters.