Abstract In his treatise The Exposition of the Content of Virgil according to Moral Philosophy , Fabius Fulgentius allegorically interpreted the contents of Virgil's epic the Aeneid. The aim of our paper is to explain the main principles of Fulgentius' allegorization by analysing the first verse of Virgil's Aeneid . In Fulgentius' view, the 12 books of the epic depicted the three main stages of a human life as they follow the “natural order”: childhood, adolescence and adulthood. In his prologue (Fulg. Cont . 87. 4–6; 87. 11–89. 3; 89. 19–90. 17), the author supports his claim by presenting an allegorical interpretation of the first line of Virgil's epic (Verg. A . 1. 1), which contains three famous words: arma (“arms”), vir (“man”) and primus (“first”). According to Fulgentius, the first term arma (“arms”) represents virtus (“manliness”) in the sense of characteristics that are available to all human individuals during childhood. The second term vir (“man”) refers to sapientia (“wisdom”), which is related to the development of the ingenium (“mind”) during adolescence. The third term primus (“first”) symbolises the adult ability ornare (“to ornament”) what we have learnt in the first phases of our life. With life experience in childhood and adolescence, a person can gradually become princeps (“a ruler”). In other words, they can be “first” within a given society and thus conclude their personal development towards perfection. As such, the contents of Virgil's Aeneid correspond to these three terms: Books 1–3 to childhood, Books 4–6 to adolescence, and Books 7–12 to adulthood.