Thomas Aquinas, the foremost medieval Scholastic, developed his own conclusions from Aristotelian premises, notably in the metaphysics of personality, creation, and Providence. As a theologian, he was responsible in his two masterpieces, the Summa theologiae and the Summa contra gentiles, for the classical systematization of Latin theology, and, as a poet, he wrote some of the most gravely beautiful eucharistic hymns in the church’s liturgy. His doctrinal system and the explanations and developments made by his followers are known as Thomism.
Normally, his work is presented as the integration into Christian thought of the recently discovered Aristotelian philosophy, in competition with the integration of Platonic thought effected by the Fathers of the Church during the first 12 centuries of the Christian Era. This view is essentially correct; more radically, however, it should also be asserted that Thomas’s work accomplished an evangelical awakening to the need for a cultural and spiritual renewal not only in the lives of individual men but also throughout the church. Thomas must be understood in his context as a mendicant religious, influenced both by the evangelism of St. Francis of Assisi, founder of the Franciscan order, and by the devotion to scholarship of St. Dominic, founder of the Dominican order.
When Thomas Aquinas arrived at the University of Paris, the influx of Arabian-Aristotelian science was arousing a sharp reaction among believers, and several times the church authorities tried to block the naturalism and rationalism that were emanating from this philosophy and, according to many ecclesiastics, seducing the younger generations. Thomas did not fear these new ideas, but, like his master Albertus Magnus (and Roger Bacon, also lecturing at Paris), he studied the works of Aristotle and eventually lectured publicly on them.
For the first time in history, Christian believers and theologians were confronted with the rigorous demands of scientific rationalism. At the same time, technical progress was requiring men to move from the rudimentary economy of an agrarian society to an urban society with production organized in trade guilds, with a market economy, and with a profound feeling of community. New generations of men and women, including clerics, were reacting against the traditional notion of contempt for the world and were striving for mastery over the forces of nature through the use of their reason. The structure of Aristotle’s philosophy emphasized the primacy of the intelligence. Technology itself became a means of access to truth; mechanical arts were powers for humanizing the cosmos. Thus, the dispute over the reality of universals—i.e., the question about the relation between general words such as “red” and particulars such as “this red object”—which had dominated early Scholastic philosophy, was left behind, and a coherent metaphysics of knowledge and of the world was being developed.
According to Aquinas, reason is able to operate within faith and yet according to its own laws. The mystery of God is expressed and incarnate in human language; it is thus able to become the object of an active, conscious, and organized elaboration in which the rules and structures of rational activity are integrated in the light of faith. In the Aristotelian sense of the word, then (although not in the modern sense), theology is a “science”; it is knowledge that is rationally derived from propositions that are accepted as certain because they are revealed by God. The theologian accepts authority and faith as his starting point and then proceeds to conclusions using reason; the philosopher, on the other hand, relies solely on the natural light of reason. Thomas was the first to view theology expressly in this way or at least to present it systematically, and in doing so he raised a storm of opposition in various quarters.
The literary form of Aquinas’s works must be appreciated in the context of his methodology. He organized his teaching in the form of “questions,” in which critical research is presented by pro and con arguments, according to the pedagogical system then in use in the universities. Forms varied from simple commentaries on official texts to written accounts of the public disputations, which were significant events in medieval university life. Thomas’s works are divided into three categories: (1) commentaries on such works as the Old and New Testaments, the Sentences of Peter Lombard (the official manual of theology in the universities), and the writings of Aristotle, (2) disputed questions, accounts of his teaching as a master in the disputations, and (3) two summae or personal syntheses, the Summa contra gentiles and the Summa theologiae, which were presented as integral introductions for the use of beginners. Numerous opuscula (“little works”), which have great interest because of the particular circumstances that provoked them, must also be noted.
The logic of Aquinas’s position regarding faith and reason required that the fundamental consistency of the realities of nature be recognized. A physis (“nature”) has necessary laws; recognition of this fact permits the construction of a science according to a logos (“rational structure”). Thomas thus avoided the temptation to sacralize the forces of nature through a naïve recourse to the miraculous or the Providence of God. For him, a whole “supernatural” world that cast its shadow over things and men, in Romanesque art as in social customs, had blurred men’s imaginations. Nature, discovered in its profane reality, should assume its proper religious value and lead to God by more rational ways, yet not simply as a shadow of the supernatural. This understanding is exemplified in the way that St. Francis of Assisi admired the birds, the plants, and the Sun.
Thomas held that human liberty could be defended as a rational thesis while admitting that determinations are found in nature. In his theology of Providence, he taught a continuous creation, in which the dependence of the created on the creative wisdom guarantees the reality of the order of nature. God moves sovereignly all that he creates; but the supreme government that he exercises over the universe is conformed to the laws of a creative Providence that wills each being to act according to its proper nature. This autonomy finds its highest realization in the rational creature: man is literally self-moving in his intellectual, volitional, and physical existence. Man’s freedom, far from being destroyed by his relationship to God, finds its foundation in this very relationship. “To take something away from the perfection of the creature is to abstract from the perfection of the creative power itself.” This metaphysical axiom, which is also a mystical principle, is the key to St. Thomas’s spirituality.