Beauty adds to goodness a relation to the cognitive faculty: so that "good" means that which simply pleases the appetite; while the "beautiful" is something pleasant to apprehend.
Thomas Aquinas, Summa Theologica (1265–1274),
Part I, Question 27, Article 1, Reply to Objection 3;
tr. Fathers of the English Dominican Province (1920, New York: Benziger Bros.)