Actual theorizing about beauty in this time period was particularly advanced by Thomas Aquinas (1224-1274). More influenced by Aristotle than by Plato, he was to philosophize in
at the new university there later in the thirteenth century. Aquinas was the first major Christian thinker to write about beauty while absorbing ideas in newly discovered and translated texts from absorbing ideas in newly discovered and translated texts form Aristotle, introduced into Europe only a century earlier through the mediation of Islamic culture. Paris
Medieval philosophers did not theorize about art as such, since their focus was on God. Unlike Plato and Aristotle, Aquinas did not defend an account of art as imitation. Aquinas theorized that beauty was an essential or transcendental property of God, like goodness and unity. Human artworks should emulate and aspire to God’s marvelous properties. The medievals followed three key principles for beautiful creations like cathedrals: proportion, light, and allegory.
Proportion. Geometry ruled the design of the church itself, built in the form of a cross, with cross-arms proportional to the arms of a human figure. It is no surprise after all, then, to find Pythagoras, the father of geometry in Notre Dame Chartres’ sculptures.
Light. In early Christian thought there is a strong dichotomy between (divine) light and (earthly) material dross. The neoplatonic book of John construes Christ as the light of the world. Since the Gothic cathedral is the house of God, light is visible proof that the divine is present. Aquinas also emphasized light, using the term claritas, which denotes internal brightness and design.
Allegory. Everything in a Gothic Cathedral is like a book full of meaning; cathedrals have been called ‘encyclopedias of stone.’ The entire cathedral is an allegory of Heaven, since it is the House of the God. All aspects of the cathedral at
had allegorical meaning: the rose window referred to the orderly cosmos. Chartres
Freeland, Cynthia. Art Theory: A Very Short Introduction.Oxford U Press: New York, 2001.