Besides tradition and his own recollection, Nepos mentions the following sources: Thucydides (Them. 1, 4, etc.); Xenophon (Ag. 1, 1); Plato’s Symposium (Alc. 2, 2); Theopompus (Alc. 11, 1); Dinon (Con. 5, 4); Timaeus (Alc. 11, 1); Silenus, Sosilus, Polybius, Sulpicius Blitho, Atticus (Hann. 13, 1 and 3); the writings of Hannibal (Hann. 13, 2); Speeches and Origines of Cato (Cat. 3, 2); Cicero’s works, especially Epp. ad Att. (Att. 16, 3). The book contains lives of twenty Greek generals from the Persian wars to the time of Alexander’s successors; a short article on Persian and Macedonian kings who were also generals; and the lives of Hamilcar and Hannibal, Cato and Atticus. The work possesses little independent value, and the following are the chief faults:
1. There are many mistakes in history and geography.
2. The biographies, and the events recorded in them, are badly arranged; eulogy is employed indiscriminately, and petty anecdotes are too frequent.
3. Important names, as Cimon and Lysander, are dismissed too briefly; others, as Atticus and Datames, are treated too fully. Many are left out altogether, as some of the leaders in the Peloponnesian war.
4. Important authorities are not used: so Herodotus, for Miltiades, Themistocles, and Pausanias. No use is made of the Hellenica of Xenophon.
For views on Nepos, cf. Gell. xv. 28, 1, ‘Cornelius Nepos rerum memoriae non indiligens.’
Pliny, N.H. v. 4, ‘Portentosa Graeciae mendacia ... quaeque alia Cornelius Nepos avidissime credidit.’
Nepos is not mentioned by Quintilian in his list of Roman historians.
In the MSS. only the Atticus and the Cato are ascribed to Nepos, the rest being entitled Liber Aemilii Probi de excellentibus ducibus exterarum gentium. It has been suggested that this arose from a misapprehension of em(endavi) Probus. There is an epigram by this Probus in the MSS., referring to poems of his and standing after the Life of Hannibal, which informs us that he was a contemporary of Theodosius (probably Theodosius I., A.D. 379-395). That the work cannot be by him is shown by the political references, which suit only the beginning of the empire, by the mention of Atticus in the preface, and by the correspondence in style between the book and the lives of Atticus and Cato, admittedly the work of Nepos; also by the fact that L. Ampelius, who probably wrote before the time of Diocletian, used the work in his Liber Memorialis.