Over at the New Liturgical Movement, Br. Lawrence Lew, O.P. provides a helpful, brief introduction to the theology that helped produce Gothic cathedrals. A sample:
St. Thomas Aquinas famously said that pulchra enim dicuntur quae visa placent, “beautiful things are those which please when seen.” As such, beautiful things, which participate in Gods beauty and receive their proper beauty from him, was apprehended through the human senses, and especially through ones sight. Sight is an important part of understanding the medieval world view, and the vision of God, by which St. Thomas meant that the glorified human intellect can come to know God as he is, is central to Scholastic theology, for the ultimate beatitude of man consists in the use of his highest function, which is the operation of his intellect. Hence, St. Thomas asserts that the blessed see the essence of God. Thus, to know Godin so far as creatures are capable of doing sois to see God, just as we might say “I see” when we mean that we have understood something. Therefore, Otto von Simson notes that the Gothic age, as has often been observed, was an age of vision.
Nevertheless, it is important to note that St. Thomas affirms that it is impossible for God to be seen by the sense of sight, or by any other sense, or faculty of the sensitive power because God is incorporeal. Hence, Gods essence is not seen by our eyes. However, our eyes can receive some form representing God according to some mode of similitude; as in the divine Scripture divine things are metaphorically described by means of sensible things. Therefore, the medieval imagination is suffused with a sacramental view of the world, so to speak, in which corporeal things represent incorporeal things, and it is through the material that we can perceive the spiritual. Abbot Suger, who was responsible for what is often recognized as the first Gothic church, said that his abbey church of St. Denis transformed that which is material to that which is immaterial.
This idea, which had been expounded by Blessed Dionysius the Areopagite, is firmly rooted in the Incarnation, and following in this tradition, St. Thomas would say that, our intellect, which is led to the knowledge of God from creatures, must consider God according to the mode derived from creatures, and, signs are given to men, to whom it is proper to discover the unknown by means of the known. This is possible because created things participate in the truth, beauty and goodness of God. As St. Thomas, commenting on Dionysius The Divine Names says, creaturely beauty is nothing other than the likeness of divine beauty participated in things. This fundamental idea, which permeates the practice of medieval art, is what lead Abbot Suger to say that the dull mind rises to truth through that which is material, thus giving a strong symbolic, even sacramental sense, to the arts. Émile Mâle, in his study of the religious art of thirteenth-century France, thus said that medieval art was before all things a symbolic art, in which form is used merely as the vehicle of spiritual meaning. The chief form of this symbolic art that dominates the landscape of the Middle Ages, is the cathedral, on which we shall concentrate in this essay.