In 1250, the year when Frederic II. died, Thomas proceeded to Paris by direction of the General of the Order. In that mother university of Christendom the Dominicans were allowed by their rule to receive the doctorate—in that and no other. For one year the candidate must hear and dispute in the Dominican school on St. Jacques Street; for another he must teach, but without ascending the cathedra, from which authoritative decisions were expected. But in Thomas’s case these two years of his Parisian apprenticeship were prolonged to seven. The university quarrelled with the representatives of the Mendicant orders just as Thomas was about to take his degree, and in the five years’ struggle which ensued all ordinary relations and procedures were suspended. For some time, indeed, the university itself was dissolved, to evade the bull of excommunication which the Pope aimed at it in the interest of the Mendicants.

In 1656 William of St. Amour sent the Pope his treatise Concerning the Dangers of these Last Times (De Periculis Novissimorum Temporum), in which he pleaded the cause of the university against the Mendicants, and told some home-truths about the greediness, the lawlessness, and the encroachments of the friars, but in an angry and excited tone, which harmed his cause. Both the assailed orders put forward their ablest men to make answer. For the Franciscans spoke John Fidanza, better known as John Bonaventura, who had come to Paris in the heat of the conflict, and had been delayed, as Thomas was, in obtaining his degree.

John was older than Thomas by several years, having been born in 1221. He had been recovered from an apparently mortal illness through the prayers of Francis of Assisi in his third year, and then received the name Bonaventura from the good man’s own lips. He entered the order in his twenty-second year, and studied in Paris under Alexander of Hales and John of Rochelle. The devout humility of the man, and his purity of character, produced as deep an impression upon his teachers as Thomas had produced upon his by the force and keenness of his intellect. Alexander used to say that “in Brother Bonaventura Adam seems not to have sinned.” John was probably the most perfect exemplar of the spirit of Francis of Assisi that was to be seen in the second generation of the order. Not by intellectual force, but by humble ministry to the commonest human needs, by the infection of an all-embracing love and the close imitation of our Lord’s humanity, he would save the world from its wanderings. Thomas and he were the best possible representatives of their respective orders, and it speaks well for both men that their differences only bound them more intimately in friendship. Each reverenced what was strongest in the other. When Thomas asked to see the books by whose help John had acquired his Christian erudition, the Franciscan pointed him to a crucifix, and said that from that he had learned all that he ever knew.

Their answers to William of St. Amour reflect the character of the men. Bonaventura defended the mendicant form of the monastic life as an ideal; but without admitting the truth of the dark picture William had drawn, he conceded that serious abuses had crept in, and that already there was need of a reformation unless matters were to be let grow worse. Thomas makes no concessions whatever. He entitles his book Against those who Assail the Worship of God and the Monastic Life (Contra Impugnantes Dei Cultum et Religionem). William and all who hold with him are the enemies of God and of His Church. The critics of the Mendicant rule are standing in the way of the forces which are sent of God to win the world to Christ. The monk, and especially the mendicant friar, is the only thorough Christian who keeps to the “counsels of perfection” our Lord gave His disciples, as well as to the precepts of obedience obligatory upon all. William uttered false and damnable doctrine when he tried to limit them to a purely ascetic life. They have the right to teach as well as to pray and mourn, and the Pope has power to open to them the doors of every secular college by his mandate.

The controversy was brought to an end in 1257, when Pope Alexander IV. at Anagni formally condemned the book of William of St. Amour, and bound the plenipotentiaries of the university by an oath to admit the Mendicants to their former footing in the university. And to signalize the victory of the friars, Thomas and Bonaventura were admitted to the doctorate on the same day, October 23d, 1257.

From the masters the head of the school in St. Jacques Street was chosen by the General of the Order, and naturally the choice fell on Thomas. Usually the place was held for a year only, and its occupant then transferred to some other field of labor. Thomas held it for four years, lecturing, preaching at least every Lent in the adjacent church, and exercising the discipline of the order over its students. The number who heard his lectures must have been great. The school at Paris, unlike that at Koeln, being a branch of the university, its lectures were open to all comers, and the renown of the Italian who had been more than a match for the ablest of the secular doctors would draw hearers. And those who came once, if they had any love for the play of pure intelligence and the fearless handling of great questions, would come again. Thomas, with all his orthodoxy, was a pretty thorough rationalist. He had full faith in the capacity of the human understanding to deal fruitfully and safely with the deepest mysteries. If his conclusions always are with the Church, it is not because he has shrunk from attending to, and even suggesting, what might be said against the doctrine under consideration. It is because he has satisfied himself that the balance of logical argument, after all objections have been weighed, is on the side of orthodoxy. In this respect his writings represent the highest point reached by the rationalistic tendency in the Middle Ages, just as Abelard represents its initiation. We find Duns Scotus, his great Franciscan rival, shrinking from his rationalism, and removing some of the mysteries of theology out of the field of logical discussion.

Of course, his most devoted hearers were the young men of the order. Of these some ninety were sent up every year from the schools in the provinces outside France; and in addition to these picked men, who came for the master’s degree, Paris had the training of all the students of Northern France. Some of the former were from Spain, where the order was engaged in combatting the Mohammedan doctors. Their needs drew Thomas’s attention to the subject of his first systematic work, the Summa contra Gentiles. Thomas puts himself upon the level of one who has no Christian convictions, but argues simply from principles of philosophic truth and of natural religion accepted by both parties. Besides these and other literary labors he attended the annual General Chapters of his order at Valenciennes in 1259, where he and Albrecht drew up the new order of studies for the young Dominicans.

In 1261 Michael Palaeologus, the Greek Emperor of Nicea, conquered Constantinople, and thus put an end to the Latin Empire established by the Fourth Crusade. But the wily Greek feared a general movement in Latin Christendom to recover the city from him, and to gain time by diplomacy he opened negotiations for the reconciliation of Eastern and Western Christendom with Urban IV., then newly chosen to the papacy. The Pope summoned Thomas Aquinas from Paris to Rome, to aid in these negotiations by his erudition and acuteness. The subject was one into which his previous studies had not conducted him, but a scholastic philosopher must be prepared to write on any topic. De omni scibili was his scope. So Thomas wrote his Treatise against the Errors of the Greeks (Opusculum contra Errores Graecorum) by the papal order. In its preparation he became at once the victim and the instrument of one of the most memorable forgeries in ecclesiastical literature. The Dominicans had followed the Latin Empire into the East, but found themselves at a loss for authorities to prove to the Greeks that the autocratic papacy was a venerable, much less a primitive institution, of the Christian Church. One of them conceived the bright thought of manufacturing a supply. So he sent to Urban IV. a long catena of quotations from the Greek fathers, especially the two Cyrils and the Council of Chalcedon, in which the papal authority and infallibility were set forth with a boldness never used even in the West. The Pope fully believed in their genuineness and handed them over to Thomas, who incorporated many of them into his opusculum, besides using them in his greater work. He knew too much about the teachings of the Greek fathers not to be staggered by the quotations as to the Procession of the Holy Spirit from the Father and the Son, and he expressed his doubts in a letter to Urban. But he was not staggered by the forger’s showing that the Greeks accepted the universal jurisdiction and infallible authority of the papacy. In this way the notion of a universal episcopate and an infallibility in the Bishop of Rome, from being the audacious whim of a few canonists, passed into the dogmatic theology of the Church, and came to be made an article of faith in our own time. (See Acton-Döllinger-Huber’s book, Janus, or the Pope and the Council, chap, iii., section 18.)

Urban IV. having brought Thomas to Italy, Clemens IV. kept him there as long as he lived, making him a professor in the university established by Innocent IV. within the Roman Curia, and as such carried him about from city to city as the Papal Court removed, and had him lecture on theology wherever the Court was staying. He also set him to the work of writing commentaries on part of the Scripture: Job, the Psalms, Canticles, Isaiah, Jeremiah, and Paul’s Epistles, besides his catena of comments on the Gospels gathered from the Latin fathers. Most important of all for our purposes, he asked him to prepare the service for Corpus Christi Day—a festival established in 1264. It was for this that Thomas wrote four of the hymns which have given him his place in the annals of hymnology, and those are his finest. And it is said that he also began his Summa in these years, but that I doubt. But in 1269 Clemens died, and it was two years before another Pope was elected. Thomas took the opportunity to escape out of the throng and noise of the Curia, and made his way back to France and to his old manner of life. He came back to Paris and lectured in St. Jacques Street, but not as the head of the school. At Paris he now found critics as well as admirers. His doctrine that individuality is dependent upon matter was censured as involving a denial of immortality, and in 1269 he wrote a treatise, Contra Averroistas, to show that this was not a necessary or even a fair inference. In the same year we find him in London attending a Chapter General of his order.

In 1271 the vacancy in the papacy ended with the selection of Gregory X., one of the best of the popes. Thomas was recalled to Italy and offered the Archbishopric of Naples, doubtless at the suggestion of Charles of Anjou, whose hands were red with the blood of the young Conradin. Thomas wisely declined it, and when, in 1272, he agreed to go to Naples as a teacher of theology, it was with the reservation that this should not bring him into close relations with the Court. Enough of his Ghibelline traditions clung to him to make him abhor the murderer of his kinsman. So in Naples he taught, and wrote at his Summa, and prayed and saw visions—his biographers say—until one day the Pope summoned him to a General Council at Lyons, with the view of proclaiming a new crusade. He obeyed the summons, but when he reached the Cistercian monastery of Fossa Nuova, on the hills above the Pontine Marshes, below Rome, he fell ill and died, March 7th, 1274. Of course the Italians knew he was poisoned, and even Dante countenances the report. The Pontine Marshes in spring are so wholesome that no other hypothesis could account for his death! His friend Bonaventura reached Lyons, but died during the sessions of the council. His earlier friend and master, Albert the Great, although his senior by thirty years, outlived him by six, dying in 1280.