[32] Thomas was held prisoner for almost one year in the family castles at Monte San Giovanni and Roccasecca in an attempt to prevent him from assuming the Dominican habit and to push him into renouncing his new aspiration.

According to the official records for his canonization, Thomas drove her away wielding a burning log—with which he inscribed a cross onto the wall—and fell into a mystical ecstasy; two angels appeared to him as he slept and said, "Behold, we gird thee by the command of God with the girdle of chastity, which henceforth will never be imperilled.

[38] When Albertus was sent by his superiors to teach at the new studium generale at Cologne, in 1248,[37] Thomas followed him, declining Pope Innocent IV's offer to appoint him abbot of Monte Cassino as a Dominican.

[25] In the spring of 1256, Thomas was appointed regent master in theology at Paris and one of his first works upon assuming this office was Contra impugnantes Dei cultum et religionem (Against Those Who Assail the Worship of God and Religion), defending the mendicant orders, which had come under attack by William of Saint-Amour.

[45] Some of the hymns that Thomas wrote for the feast of Corpus Christi are still sung today, such as the Pange lingua (whose final two verses are the famous Tantum ergo), and Panis angelicus.

Prior to this time, the Roman Province had offered no specialized education of any sort, no arts, no philosophy; only simple convent schools, with their basic courses in theology for resident friars, were functioning in Tuscany and the meridionale during the first several decades of the order's life.

As the Apostle says in 1 Corinthians 3:1–2, as to infants in Christ, I gave you milk to drink, not meat, our proposed intention in this work is to convey those things that pertain to the Christian religion in a way that is fitting to the instruction of beginners.

A new convent of the Order at the Church of Santa Maria sopra Minerva began in 1255 as a community for women converts but grew rapidly in size and importance after being given over to the Dominicans friars in 1275.

In response to these perceived errors, Thomas wrote two works, one of them being De unitate intellectus, contra Averroistas (On the Unity of Intellect, against the Averroists) in which he reprimands Averroism as incompatible with Christian doctrine.

Eleonore Stump says, "It has also been persuasively argued that Thomas Aquinas's De aeternitate mundi was directed in particular against his Franciscan colleague in theology, John Pecham.

"[58] Thomas was deeply disturbed by the spread of Averroism and was angered when he discovered Siger of Brabant teaching Averroistic interpretations of Aristotle to Parisian students.

[59] On 10 December 1270, the Bishop of Paris, Étienne Tempier, issued an edict condemning thirteen Aristotelian and Averroistic propositions as heretical and excommunicating anyone who continued to support them.

For example, G. K. Chesterton wrote that "His experiences included well-attested cases of levitation in ecstasy; and the Blessed Virgin appeared to him, comforting him with the welcome news that he would never be a Bishop.

"[63] It is traditionally held that on one occasion, in 1273, at the Dominican convent of Naples in the chapel of Saint Nicholas,[64] after Matins, Thomas lingered and was seen by the sacristan Domenic of Caserta to be levitating in prayer with tears before an icon of the crucified Christ.

But the historian Ludovico Antonio Muratori reproduces the account made by one of Thomas's friends, and this version of the story gives no hint of foul play.

[88] Pope Pius V proclaimed St. Thomas Aquinas a Doctor of the Church on 15 April 1567,[89] and ranked his feast with those of the four great Latin fathers: Ambrose, Augustine of Hippo, Jerome, and Gregory.

A good example is Aeterni Patris, the 1879 encyclical by Pope Leo XIII stating that Thomas's theology was a definitive exposition of Catholic doctrine.

[103] This criticism is illustrated with the following example: according to Russell, Thomas advocates the indissolubility of marriage "on the ground that the father is useful in the education of the children, (a) because he is more rational than the mother, (b) because, being stronger, he is better able to inflict physical punishment.

"[104] Even though modern approaches to education do not support these views, "No follower of Saint Thomas would, on that account, cease to believe in lifelong monogamy, because the real grounds of belief are not those which are alleged".

[104] Thomas Aquinas viewed theology, "the sacred doctrine", as a science,[70] by which he meant a field of study in which humanity could learn more by its own efforts (as opposed to being totally dependent on having divine revelation planted into our minds).

[70] Thomas blended Greek philosophy and Christian doctrine by suggesting that rational thinking and the study of nature, like revelation, were valid ways to understand truths pertaining to God.

This led him to propose five statements about the divine qualities: Following Augustine of Hippo, Thomas defines sin as "a word, deed, or desire, contrary to the eternal law.

[129] In the Summa Theologica, Thomas begins his discussion of Jesus Christ by recounting the biblical story of Adam and Eve and by describing the negative effects of original sin.

[132] With respect to Paul's assertion that Christ, "though he was in the form of God ... emptied himself" (Philippians 2:6–7) in becoming human, Thomas offered an articulation of divine kenosis that has informed much subsequent Catholic Christology.

For this reason the Church not only admits to Penance those who return from heresy for the first time, but also safeguards their lives, and sometimes by dispensation, restores them to the ecclesiastical dignities which they may have had before, should their conversion appear to be sincere: we read of this as having frequently been done for the good of peace.

[146] Regarding magic, Thomas wrote that: A mention of witchcraft appears in the Summa Theologicae[151] and concludes that the church does not treat temporary or permanent impotence attributed to a spell any differently to that of natural causes, as far as an impediment to marriage.

"[153] The famous 15th-century witch-hunter's manual, the Malleus Maleficarum, also written by a member of the Dominican Order, begins by quoting Thomas Aquinas ("Commentary on Pronouncements" Sent.4.34.I.Co.)

Thomas Aquinas wrote several important commentaries on Aristotle's works, including On the Soul, On Interpretation, Posterior Analytics, Nicomachean Ethics, Physics and Metaphysics.

Thomas Aquinas believed "that for the knowledge of any truth whatsoever man needs divine help, that the intellect may be moved by God to its act.

[187] Aquinas' doctrines of the Fair Price,[188] of the right of tyrannicide and of the equality of all the baptized sons of God in the Communion of saints established a limit to the political power to prevent it from degenerating into tyranny.