We do not know the full name of Censorinus, but the cognomen Censorinus has illustrious ancestors (L.Marcius Censorinus, consul in 149, is mentioned in De die natali - chap. 11). From ancient sources we know that Censorinus was a grammaticus and had composed a manual of support to his teaching and piece of work on accents: in De grammatica, Cassiodorus mentions him with Palaemon, Foca and Probus among auctores temporum superiorum which dealt with de arte grammatica, and in De musica he states that de accentibus … subtiliter disputauit; Priscian in De litteris considers him doctissimus artis grammaticae and in De praenominibus he says: Censorinus uero plenissime de his docet in libro, quem de accentibus scribit. Neither of these two works has come to us. On the other hand, we have, even though incomplete, De die natali, a short work dedicated by Censorinus to his friend Quintus Cerellius in the occasion of his birthday. We do not know much else on Censorinus, but in two parts of his work, precisely when he illustrates the different ways of calculating time, he tells us the exact year in which he is writing, i.e. 238 AD (chapters 18 and 21). The recipient, Quintus Cerellius, is described in chapter 15: he was a provincial of equestrian rank, who had held civil and priestly offices in his municipality, acquiring great prestige and influence. Censorinus praises with emphasis the eloquence that made him famous in provincial courts and in Rome itself. A complex calculation of the various phases of life, divided into periods of seven years (hebdomades), informs us that Cerellius was 49 years old when Censorinus dedicated his book to him (chapters 14-15). [R. Tabacco; trad. M. Formentelli]