This paper begins in the year 1569, when a hefty commentary on the Lives of Cornelius Nepos was published in Paris by one of the Royal Professors, Denys Lambin (known to classicists as Lambinus). The event intrigued me for two reasons. Firstly because, in France at that time, history was not a proper subject for professors. A professor could deal in Greek and Latin poetry, in oratory, philosophy, maths or Hebrew, or of course in the degree subjects theology, medicine and law; but history, including ancient history, was mostly a popular interest among the cultured ruling class, who preferred to read it in elegant vernacular versions, like Amyot's Diodorus and Plutarch, not in the dusty didactic form of text and commentary. So why did a professor, famous for his work on poetry and philosophy, suddenly devote himself to Nepos? The second puzzle was that, within weeks of publishing this commentary, Lambinus was violently attacked for it, and came close to losing both his job and his life. How, I wondered, could commenting on Nepos so seriously endanger the health?