The contested claim is that James Joyce derived part of his aesthetic theory from the opinion of Thomas Aquinas that beauty is marked with unity, harmony, and then radiance, or in Latin, claritas . The last term was puzzling to Stephen Dedalus, in PORTRAIT OF THE ARTIST, until he identified claritas with quidditas or the whatness of a thing. The thesis is that Joyce has effectively grasped the medieval concept in his modernist aesthetic, and may have developed his idea from an acquaintance with the Thomistic theory of knowledge. The demonstration of the case in the SUMMA THEOLOGIAE is what...