Bettinelli's aesthetic proposal is not a theoretical one; it springs from a practical aim: to restore great Italian poetry. But this aim leads Bettinelli to face problems of a specifically theoretical kind like the relation between invention and imitation, the capacity of great poetry to be enjoyed at all times and in all places independently of the social and political environment in which it is born, the meaning of imitation. These are the topics which, present in Lettere Virgiliane and in Lettere Inglesi, where the polemical accent conceals the theoretical aim, are fully developed in Dell'Entusiasmo delle belle arti. In this work the need to go back to the sources of great poetry leads Bettinelli to emphasize the moment of experience in the aesthetic phenomenon. This phenomenon is not studied through the analysis of the formal characteristics of the aesthetic object; it is studied through the moments of artistic creation and aesthetic enjoyment, which are always conceived as exceptional events, not connected to daily life.
In this general view Bettinelli develops and lays emphasis on categories like genius, "transfusion", the experience of the sublime as an experience of overstepping limits and form, which in the great classical Aesthetics remained unperceived. In Dell'Entusiasmo delle belle arti these categories gain vigour; they split the classical ideal of formal perfection, of equilibrium, of good taste which Bettinelli believes in as the characteristics of great poetry. Consequently the classical rule of "imitation of nature" changes its meaning; the new value of the sublime - which is not always beautiful - appears; the aesthetic experience seems to acquire features that are different from the features of experience of knowledge. These deviations from the classical ideal are sometimes only hints; nevertheless they are able to justify an interest in an empiricist "aestheticien" like Bettinelli.