"There is no such thing as understanding art in any period apart from the philosophy of that period. Philosophy inspires art, and art reflects philosophy. We can never tell what the art of an age is unless we know what is the thought of the age. If the thought is lofty and spiritual, art will be lofty and spiritual; if the thought is base and material, art will be base and material. If the thought is of the heavens heavenly, art will be of the heavens heavenly; if the thought is of the earth earthly, art will be of the earth earthly. In that period of Grecian history, for example, when Plato and Socrates and Aristotle were giving eternal truths to men, the clear lines of the Parthenon and the airy Ionic of the Erechtheion served as so many petrified incarnations of their thought. Closer to our own times, when Rousseau set loose this exaltation of the ego and the romanticism of sense-passion, artists were found drinking at his fountain the shallow drafts of hatred for academic tradition, a license of inspiration, and a glorification of fleshy sensibilities. And now in our own day, what is the philosophical inspiration of Futurism and its wild love of novelty and 'absolute commencements,' motion for motion's sake, but the thought of Henri Bergson? What is the philosophical inspiration of Cubism, with is unrelated blocks, but the philosophy of Pluralism, which maintains that the multiple does not imply the unit? What is the whole inspiration of modern art but a Subjectivism introduced by Kant and his school, the heritage of which is a belief that no work of art itself is beautiful, but that it is our psychic or mental states that are beautiful, either because we project these states to the object, which is the Einfühlung theory, or because they harmonize with the tastes and commandments of society, which is the sociological theory, or because they produce intersecting reactions, which is the Pragmatic theory? If modern philosophy explains modern art, medieval philosophy explains medieval art. If we are to understand why they painted and why hey sculptured and why they built a certain way, we must ask ourselves how they thought, for art is the lyrical expression of philosophy. Their civilization was much different from our own; in the thirteenth century, Christendom knew but one Church. There was just one Faith, one Lord, one Baptism, one Church. Since it was one in its rule of faith, it is easy to extract those basic principles of medieval life which served as the inspiration of their art. These principles are threefold: (1) Impersonalism, (20 Dogmatism, and (3) Sacramentalism."
-Old Errors and New Labels by Fulton J. Sheen, c. 1931.