St. Thomas has left us no treatise on beauty. His aesthetics, if they exist, are implicit. As a result, the commentator who aims to set out the thought of St.Thomas on beauty can only present a hypothetical reconstruction. Setting out the esthetics of St. Thomas amounts therefore for the commentator to taking part, whether he wishes to or not, in the tradition that claims to a greater or lesser extent to be that of Aquinas, namely the «Thomist» tradition. From the strictly historical point of view it is illusory to wish to grasp the aesthetics of Thomas himself. This article puts forward a possible reconstruction of the aesthetics of St. Thomas. It sets out firstly the objective ontological conditions attributed by Thomas to the beautiful: ...