Lucius Ampelius is the author of the Liber memorialis, a work of uncertain date, but probably written between the third and fourth centuries AD. In the preface, the author dedicates the Liber memorialis to a Macrinus, who is unlikely to be the same person as the Emperor Macrinus. The texts aims to let Macrinus know quid sit mundus, quid elementa, quid orbis terrarum ferat, uel quid genus humanum peregerit. The short treatise is accordingly written with an eminently didactic or educational purpose, and contains fifty short monographic chapters gathering elementary notions on astronomical, natural, geographical, mythological, historical and political subjects. A simple, very clear style, entirely appropriate to the educational purpose of the work, characterises the presentation of the subject matter. [D. Paniagua; tr. L. Battezzato]