The book investigates theories dating from the 13th to the 18th century on the moral indifference of human action with a view to substantiating the hypothesis of a heterogeneous genealogy of the specifically modern concept of 'aesthetics'. Aesthetic discourse on art did not develop of its own self and in its own right but was essentially based on genuinely moral-theological concepts (or concepts evolving in the context of moral theology) relating to the eventuality of human action being adiaphoric in origin. Both in methodological terms and in conjunction with its subject, this study proposes an aetiology, rather than a pre-history, of aesthetic thinking.