From Stuart, Duane Reed. 1909. Tacitus: The Agricola. New York: Macmillan. Pp. xiv-xv.
Besides the Agricola four works bearing the name of Tacitus have come down to us:
1. The Dialogus de Oratoribus, an essay in literary criticism, cast in the form of a conversation. The speakers inquire into the reasons for the decadence of oratory and discuss the relative merits of poetry and eloquence. Scholars are at variance as to the date of composition. The work appeared either in the reign of Titus, 79-81 A.D., or not until after the death of Domitian in 96 A.D.
2. The Germania so-called, being an account of ancient Germany and the Germans. The treatise was published in 98 A.D., not long after the appearance of the Agricola.
3. The Histories, the first of the purely historical works of Tacitus, presented in annalistic form the events of imperial history from January 1, 69, down to the death of Domitian. The work contained probably fourteen, certainly no less than twelve, books. Of these the first four and a part of the fifth are extant. The Histories were published during the years following 104 A.D., probably in installments, and were completed before Tacitus went out as proconsul of Asia in 112.
4. The Annals, formally entitled Ab Excessu Divi Augusti Libri. Herein were set forth the reigns of the four emperors of the Julian line who succeeded Augustus; namely, Tiberius, Caligula, Claudius, and Nero. The narrative presumably was carried down to the date at which the Histories begin. Of the sixteen or eighteen original books — the number is uncertain — we have books 1-4 (xv) and 12-15 complete and portions of four other books. The work was begun after the return of Tacitus from Asia and could not have been finished until some time after the accession of Hadrian.
It is thus evident that the major portion of Tacitus's literary activity coincided with the reign of Trajan. Of course Tacitus wrote speeches and presumably he answered the letters of his friend Pliny. None of these has come down to us.