The concepts of progress and decline play a dominant role in ancient views on literary history. Roman culture inherited from Aristotle the idea that the arts gradually mature. Whereas archaic and classical Greek literature was generally known to the Romans as a corpus of canonical works that represented the acme of each genre, Latin literature gave the Romans the image of a long march of advancement towards the Greek models’ perfection. From Aristotle onwards, progress is conceived as an addition of pertinent procedures. The attainment of maturity does not entail decadence, but rather the possibility of creating works fully corresponding to the nature of the genre. If an acme is thought to have been reached, later authors may aim at what they regard as a more authentic acme; the process thus continues. Various Latin texts show that a continuous progress towards an ideal perfection is not excluded. The idea of decadence, in Cicero’s Brutus and in post-Augustan texts, relates to reasons that do not concern ‘internal’ dynamics of artistic development, but the distrust in the conditions and prospects of politics and morality in the ‘external’ context, including the lack of self-discipline in an excessive display of increasingly sophisticated formal virtuosity.