Livy, in his ab urbe condita, makes it clear that origins are subject to change: to growth and development, or to decay and decline. This temporal framework is closely connected with the circularity of exemplarity, of deeds that can be re-enacted again and again. This draws attention to the fact that Livy himself, by writing this aetiological account, also acts in an exemplary way, exhorting his readers to do something similar for the city they see preserved ‘even now’. In Vergil’s Aeneid, the aetion of the Game of Troy in Book 5 brings home the message that what had been spoken as fatum in the remote past is now being fulfilled in the Augustan present. Yet with the so-called reconciliation of Juno, the aetion of the lusus Troiae appears in a new light: it becomes an act of naming that is not to be repeated—a thing of the past. The aetion, ultimately, signals both a strong sense of arrival, while also pointing to the fact that, eventually, time will have to move on. In Ovid’s Fasti, time becomes even more dynamic. In the constant sequence of the days of the Roman calendar, each new ‘now’ constructed by the poet is soon supplanted by a new day and a new ‘now’. However, another axis of time comes into play here as well: the eternity of the city of Rome, which is guaranteed by its closeness to the gods. Aetia form the points at which the passage of days, the time of history, and the eternal power of the gods are brought into contact.