The Aesthetics of Thomas Aquinas is written by

The correct option is Umberto Eco.

Step-by-step Explanation:
1. Origin of the Work: The Aesthetics of Thomas Aquinas (originally published in Italian as Il problema estetico in Tommaso d'Aquino in 1956) is a key scholarly work by the famous Italian semiotician, philosopher, and novelist Umberto Eco. It was developed from his doctoral thesis at the University of Turin, where he explored the concept of beauty and aesthetic theory in the writings of the medieval theologian Thomas Aquinas.
2. Eco's Academic Focus: Before becoming globally famous for his novels like The Name of the Rose, Eco was deeply invested in medieval studies and semiotics. In this book, Eco reconstructs and analyzes Aquinas's ideas on proportion, integrity, and clarity (the three conditions of beauty according to Aquinas).
3. Analyzing the Other Options:
- James Joyce: Although Joyce was heavily influenced by Thomist philosophy and Aquinas's aesthetic theories (which he discusses in A Portrait of the Artist as a Young Man), he did not write this academic study. In fact, Umberto Eco also wrote a separate book analyzing Joyce's relationship with Aquinas called The Aesthetics of Chaosmos: The Middle Ages of James Joyce.
- Walter Pater: He was a 19th-century English essayist, art critic, and writer who was a leading figure of the Aesthetic Movement, famous for works like Studies in the History of the Renaissance, but did not write on Aquinas's aesthetics.
- Matthew Arnold: He was a Victorian poet and cultural critic best known for his essay collection Culture and Anarchy, focusing on social and educational criticism rather than medieval scholastic philosophy.