Aquinas is held in the Catholic Church to be the model teacher for those studying for the priesthood (Code of Canon Law, Can. 252, §3). The works for which he is best-known are the Summa Theologica and the Summa Contra Gentiles. One of the 33 Doctors of the Church, he is considered by many Catholics to be the Catholic Church's greatest theologian and philosopher. Consequently, many institutions of learning have been named after him.
At the age of five, Aquinas began his early education at a monastery. After his elementary education, he went on to study at the University of Naples, where he studied for six years before leaving in his sixteenth year. Aquinas had come under the influence of the Dominicans, who wished to enlist the ablest young scholars of the age. The Dominicans and the Franciscans represented a revolutionary challenge to the well-established clerical systems of Medieval Europe.
Aquinas's change of heart did not please his family. On the way to Rome, his brothers seized him and took him back to his parents at the castle of Monte San Giovanni Campano. He was held captive for a year so he would renounce his new aspiration. According to Aquinas's earliest biographers, two of his brothers even brought a prostitute to tempt him, but he drove her away. After this, it is said that two angels came down from the heavens and girded his loins, providing Aquinas with a life of chastity. Finally, Pope Innocent IV intervened and Aquinas assumed the habit of St. Dominic in his 17th year.
His superiors saw his great aptitude for theological study. In late 1244, they sent him to the Dominican school in Cologne, where Albertus Magnus was lecturing on philosophy and theology. In 1245, Aquinas accompanied Albertus to the University of Paris, where they remained for three years. During this time, Aquinas threw himself into the controversy between the university and the Friar-Preachers about the liberty of teaching. Aquinas actively resisted the university's speeches and pamphlets. When the Pope was alerted of this dispute, the Dominicans selected Aquinas to defend his order. He did so with great success. He even overcame the arguments of Guillaume de St Amour, the champion of the university, and one of the most celebrated men of the day.
Aquinas then graduated as a bachelor of theology. In 1248, he returned to Cologne, where he was appointed second lecturer and magister studentium. This year marks the beginning of his literary activity and public life.
For several years, Aquinas remained with Albertus Magnus. Aquinas's long association with this great philosopher-theologian was the most important influence in his development. In the end, he became a comprehensive scholar who permanently utilized Aristotle's method.
In 1256, Aquinas, along with his friend Bonaventura, began to lecture on theology in Paris and Rome and other Italian towns. From this time on, his life was one of incessant toil. Aquinas continually served in his order, frequently made long and tedious journeys, and constantly advised the reigning pontiff on affairs of state.
In 1259, Aquinas was present at an important meeting of his order at Valenciennes. At the solicitation of Pope Urban IV, he moved to Rome no earlier than late 1261. In 1263, he attended the London meeting of the Dominican order. In 1268, he lectured in Rome and Bologna. Throughout these years, he remained engaged in the public business of the Catholic Church.
From 1269 to 1271, Aquinas was again active in Paris. He lectured to the students, managed the affairs of the Catholic Church, and advised the king, Louis VIII, his kinsman, on affairs of state. In 1272, the provincial chapter at Florence empowered him to begin a new stadium generale at a location of his choice. Later, the chief of his order and King Charles II brought him back to the professor's chair at Naples.
All this time, Aquinas preached every day, and he wrote homilies, disputations, and lectures. He also worked diligently on his great literary work, the Summa Theologica. The Catholic Church offered to make him archbishop of Naples and abbot of Monte Cassino, but he refused both.
It should be noted that, as a Dominican Friar, Aquinas was supposed to participate in the mortification process. He did not; a remarkable thing considering how devoted to the faith he was known to be. At his canonization trial, it became evident he did not practice such rites. "The forty-two witnesses at the canonization trial had little to report concerning extraordinary acts of penance, sensational deeds, and mortifications...they could only repeat unanimously, again and again: Thomas had been a pure person, humble, simple, peace-loving, given to contemplation, moderate, a lover of poetry". These endearing qualities helped him in his beatification. The witnesses praised Thomas for his rational thought.
It is reported in Chesterton's book that Aquinas placed his essay concerning the Eucharist at the bottom of the cross. The friars there claimed to see the image of Jesus descending upon it, and a voice was heard to say, "Thomas, thou hast written well concerning the sacrament of My Body.”On one occasion, monks claimed to have found him levitating. The twentieth century Catholic writer/convert G. K. Chesterton describes these and other stories in his work on Aquinas, The Dumb Ox, a title based on early impressions that Aquinas was not proficient in speech. Chesterton quotes Albertus Magnus' refutation of these impressions: "You call him 'a dumb ox,' but I declare before you that he will yet bellow so loud in doctrine that his voice will resound through the whole world.
Aquinas had a dark complexion, large head and receding hairline, and he was of large stature. His manners showed his breeding, for people described him as refined, affable and lovable. In arguments, he maintained self-control and won over his opponents by his personality and great learning. His tastes were simple. He impressed his associates with his power of memory. When absorbed in thought, he often forgot his surroundings, but he was able to express his thoughts systematically, clearly and simply. Because of his keen grasp of his materials, Aquinas does not make the reader his companion in the search for truth; rather, he teaches authoritatively. On the other hand, he felt dissatisfied by the insufficiency of his works as compared to the divine revelations he had received.
He is said to have spoken on the morning of 6 December 1273, his last words: "Such secrets have been revealed to me that all I have written now appears of little value."
The 1276 condemnation "has often been depicted as the most dramatic and significant doctrinal censure in the history of the University of Paris, and a landmark in the history of medieval philosophy and theology." In fact, it took many years for Thomas's reputation to recover from this censure.
In January 1274, Pope Gregory X directed Thomas to attend the Second Council of Lyons. Aquinas's task was to investigate and, if possible, settle the differences between the Greek and Latin churches. Far from healthy, he undertook the journey. On the way, he stopped at the castle of a niece and there became seriously ill. Aquinas desired to end his days in a monastery. However, he was unable to reach a house of the Dominicans, so he was taken to the Cistercian monastery of Fossa Nuova. After a lingering illness of seven weeks, Aquinas died on 7 March 1274.
In The Divine Comedy, Dante sees the glorified spirit of Aquinas in the Heaven of the Sun with the other great exemplars of religious wisdom. Dante also asserts that Aquinas died by poisoning, on the order of Charles of Anjou (Purg. xx. 69). Villani (ix. 218) cites this belief, and the Anonimo Fiorentino describes the crime and its motive. But the historian Muratori reproduces the account made by one of Aquinas's friends, and this version of the story gives no hint of foul play.
Fifty years after Thomas's death, Pope John XXII, seated in Avignon, pronounced Thomas a saint of the Catholic Church. Thomas's theology had begun its rise to prestige. Two centuries later, in 1567, Pope Pius V ranked the festival of St. Thomas Aquinas with those of the four great Latin fathers: Ambrose, Augustine, Jerome, and Gregory. However, in the same period the Council of Trent would still turn to Duns Scotus before Thomas, as a source of arguments in defence of the Catholic Church. Even though Duns Scotus was consulted at the Council of Trent, Aquinas still maintained the honor of having his Summa Theologica placed on the altar alongside the Bible and the Decretals. It was not until the First Vatican Council that Thomas was elevated to the preeminent status of "teacher of the church".
In his Encyclical of 4 August 1879, Pope Leo XIII stated that Aquinas's theology was a definitive exposition of Catholic doctrine. Thus, he directed the clergy to take the teachings of Aquinas as the basis of their theological positions. Leo XIII also decreed that all Catholic seminaries and universities must teach Aquinas's doctrines, and where Aquinas did not speak on a topic, the teachers were "urged to teach conclusions that were reconcilable with his thinking." In 1880, Aquinas was declared patron of all Catholic educational establishments.
In a monastery at Naples, near the cathedral of St. Januarius, a cell in which he supposedly lived is still shown to visitors. His remains were placed in the Church of the Jacobins in Toulouse in 1369. Between 1789 and 1974, they were held in Saint Sernin basilica of Toulouse. In 1974, they were returned to the Church of the Jacobins, where they have remained ever since.
The Roman Catholic Church today celebrates his feast on January 28, the date of publication of the Summa. Before the revision of the Roman calendar in 1969 the feast was observed on March 7, the day of his death.
The philosophy of Aquinas has exerted enormous influence on subsequent Christian theology, especially that of the Roman Catholic Church, extending to Western philosophy in general, where he stands as a vehicle and modifier of Aristotelianism, which he fused with the thought of Augustine. Philosophically, his most important and enduring work is the Summa Theologica, in which he expounds his systematic theology of the quinquae viae.
Though one may deduce the existence of God and His Attributes (One, Truth, Good, Power, Knowledge) through reason, certain specifics may be known only through special revelation (Like the Trinity). In Aquinas's view, special revelation is equivalent to the revelation of God in Jesus Christ. The major theological components of Christianity, such as the Trinity and the Incarnation, are revealed in the teachings of the Catholic Church and the Scriptures and may not otherwise be deduced.
Supernatural revelation (faith) and natural revelation (reason) are complementary rather than contradictory in nature, for they pertain to the same unity: truth.
Virtue denotes a certain perfection of a power. Now a thing's perfection is considered chiefly in regard to its end. But the end of power is act. Wherefore power is said to be perfect, according as it is determinate to its act.
Aquinas defined the four cardinal virtues as prudence, temperance, justice, and fortitude. The cardinal virtues are natural and revealed in nature, and they are binding on everyone. There are, however, three theological virtues: faith, hope, and charity. These are supernatural and are distinct from other virtues in their object, namely, God:
Now the object of the theological virtues is God Himself, Who is the last end of all, as surpassing the knowledge of our reason. On the other hand, the object of the intellectual and moral virtues is something comprehensible to human reason. Wherefore the theological virtues are specifically distinct from the moral and intellectual virtues.
Furthermore, Aquinas distinguished four kinds of law: eternal, natural, human, and divine. Eternal law is the decree of God that governs all creation. Natural law is the human "participation" in the eternal law and is discovered by reason. Natural law, of course, is based on "first principles":
. . . this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this . . .
The desires to live and to procreate are counted by Aquinas among those basic (natural) human values on which all human values are based.
Aquinas denied that human beings have any duty of charity to animals because they are not persons. Otherwise, it would be unlawful to use them for food. But this does not give us license to be cruel to them, for "cruel habits might carry over into our treatment of human beings.
Aquinas believed that the existence of God is neither obvious nor unprovable. In the Summa Theologica, he considered in great detail five reasons for the existence of God. These are widely known as the quinquae viae, or the "Five Ways."
Concerning the nature of God, Aquinas felt the best approach, commonly called the via negativa, is to consider what God is not. This led him to propose five statements about the divine qualities:
In this approach, he is following, among others, the Jewish philosopher Maimonides.
This Trinity exists independently from the world. It transcends the created world, but the Trinity also decided to communicate God's self and God's goodness to human beings. This takes place through the Incarnation of the Word in the person of Jesus Christ and through the indwelling of the Holy Spirit (indeed, the very essence of the Trinity itself) within those who have experienced salvation by God.
Aquinas argued against several specific contemporary and historical theologians who held differing views about Christ. In response to Photinus, Aquinas stated that Jesus was truly divine and not simply a human being. Against Nestorius, who suggested that God merely inhabited the body of Christ, Aquinas argued that the fullness of God was an integral part of Christ's existence. However, countering Apollinaris' views, Aquinas held that Christ had a truly human (rational) soul, as well. This produced a duality of natures in Christ, contrary to the teachings of Arius. Aquinas argued against Eutyches that this duality persisted after the Incarnation. Aquinas stated that these two natures existed simultaneously yet distinguishably in one real human body, unlike the teachings of Manichaeus and Valentinus.
In short, "Christ had a real body of the same nature of ours, a true rational soul, and, together with these, perfect Deity." Thus, there is both unity (in his one hypostasis) and diversity (in his two natures, human and Divine) in Christ.
This ultimate goal carries implications for one's present life on earth. Aquinas stated that an individual's will must be ordered toward right things, such as charity, peace, and holiness. He sees this as the way to happiness. Aquinas orders his treatment of the moral life around the idea of happiness. The relationship between will and goal is antecedent in nature "because rectitude of the will consists in being duly ordered to the last end [that is, the beatific vision]." Those who truly seek to understand and see God will necessarily love what God loves. Such love requires morality and bears fruit in everyday human choices.
Many modern ethicists both within and outside the Catholic Church (notably Philippa Foot and Alasdair MacIntyre) have recently commented on the possible use of Aquinas's virtue ethics as a way of avoiding utilitarianism or Kantian deontology. Through the work of twentieth century philosophers such as Elizabeth Anscombe (especially in her book Intention), Aquinas's principle of double effect specifically and his theory of intentional activity generally have been influential.
It is remarkable that Aquinas's aesthetic theories, especially the concept of claritas, deeply influenced the literary practice of modernist writer James Joyce, who used to extol Aquinas as being second only to Aristotle among Western philosophers. The influence of Aquinas's aesthetics also can be found in the works of the Italian semiotician Umberto Eco, who wrote an essay on aesthetic ideas in Aquinas (published in 1956 and republished in 1988 in a revised edition).