Aquinas was born in Aquino c. 1225, according to some authors in the father Count Landulf of Aquino's castle placed in Roccasecca, in the same Contea di Aquino (Kingdom of Sicily, in the present-day: Lazio). Through his mother, Theodora Countess of Theate, Aquinas was related to the Hohenstaufen dynasty of Holy Roman emperors. Landulf's brother Sinibald was abbot of the original Benedictine abbey at Monte Cassino. While the rest of the Aquinas sons pursued a military career, the family intended for Aquinas to follow his uncle into the abbacy; this would have been a normal career path for a younger son of southern Italian nobility.

At the age of five, Aquinas began his early education at Monte Cassino but after the military conflict that broke out between the Emperor Frederick II and Pope Gregory IX spilled into the abbey in early 1239, Landulf and Theodora had Aquinas enrolled at the studium generale (university) recently established by Frederick in Naples. It was here that Aquinas was probably introduced to Aristotle, Averroes and Maimonides, all of whom would influence his theological philosophy. It was also during his study at Naples that Aquinas came under the influence of John of St. Julian, a Dominican preacher in Naples, who was part of the active effort by the Dominican order to recruit devout followers. Here his teacher in arithmetic, geometry, astronomy, and music was Petrus de Ibernia.

At age nineteen, Thomas resolved to join the Dominican Order. Aquinas' change of heart did not please his family, who had expected him to become a Benedictine monk. In an attempt to prevent Theodora's interference in Aquinas' choice, the Dominicans arranged for Aquinas to be removed to Rome, and from Rome, sent to Paris. On his way to Rome, his brothers, per Theodora's instructions, seized him as he was drinking from a spring and took him back to his parents at the castle of Monte San Giovanni Campano. He was held for two years in the family homes 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. Political concerns prevented the Pope from ordering Aquinas' release, extending the detention, a detention which Aquinas spent tutoring his sisters and communicating with members of the Dominican Order. Family members became desperate to dissuade Aquinas, who remained determined to join the Dominicans. At one point, two of his brothers hired a prostitute to seduce him, but he drove her away, wielding a burning stick. According to legend, that night two angels appeared to him as he slept and strengthened his determination to remain celibate. By 1244, seeing that all of her attempts to dissuade Aquinas had failed, Theodora sought to save the family's dignity, arranging for Aquinas to escape at night through his window. In her mind, a secret escape from detention was less damaging than an open surrender to the Dominicans. Aquinas was sent first to Naples and then to Rome to meet Johannes von Wildeshausen, the Master General of the Dominican Order.

In 1245, Aquinas was sent to study at the University of Paris' Faculty of Arts where he most likely met Dominican scholar Albertus Magnus, then the Chair of Theology at the College of St. James in Paris. When Albertus was sent by his superiors to teach at the new studium generale at Cologne in 1248, Aquinas followed him, declining Pope Innocent IV's offer to appoint him abbot of Monte Cassino as a Dominican. Albertus then appointed the reluctant Aquinas magister studentium. After failing in his first theological disputation, Albertus prophetically exclaimed: "We call him the dumb ox, but in his teaching he will one day produce such a bellowing that it will be heard throughout the world."

Aquinas taught in Cologne as an apprentice professor (baccalaureus biblicus), instructing students on the books of the Old Testament and writing Expositio super Isaiam ad litteram (Literal Commentary on Isaiah), Postilla super Ieremiam (Commentary on Jeremiah) and Postilla super Threnos (Commentary on Lamentations). Then in 1252 he returned to Paris to study for the master's degree in theology. He lectured on the Bible as an apprentice professor, and upon becoming a baccalaureus Sententiarum (bachelor of the Sentences) devoted his final three years of study to commenting on Peter Lombard's Sentences. In the first of his four theological syntheses, Aquinas composed a massive commentary on the Sentences entitled Scriptum super libros Sententiarium (Commentary on the Sentences). Aside from his masters writings, he wrote De ente et essentia (On Being and Essence) for his fellow Dominicans in Paris.

In spring of 1256, Aquinas 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. During his tenure from 1256 to 1259, Aquinas wrote numerous works, including: Questiones disputatae de veritate (Disputed Questions on Truth), a collection of twenty-nine disputed questions on aspects of faith and the human condition prepared for the public university debates he presided over on Lent and Advent; Quaestiones quodlibetales (Quodlibetal Questions), a collection of his responses to questions posed to him by the academic audience; and both Expositio super librum Boethii De trinitate (Commentary on Boethius's De trinitate) and Expositio super librum Boethii De hebdomadibus (Commentary on Boethius's De hebdomadibus), commentaries on the works of 6th century philosopher Anicius Manlius Severinus Boethius. By the end of his regency, Aquinas was working on one of his most famous works, Summa contra Gentiles.

Around 1259, Aquinas returned to Naples where he lived until he arrived in Orvieto around September 1261. In Orvieto, he was appointed conventual lector, in charge of the education of friars unable to attend a studium generale. During his stay in Orvieto, Aquinas completed his Summa contra Gentiles, and wrote the Catena Aurea (The Golden Chain). He also wrote the liturgy for the newly created feast of Corpus Christi and produced works for Pope Urban IV concerning Greek Orthodox theology, e.g. Contra errores graecorum (Against the Errors of the Greeks). In 1265 he was ordered by the Dominicans to establish a studium for the Order in Rome at the priory of Santa Sabina, which he did from 1265 until he was called back to Paris in 1268. It was in Rome that Aquinas began his most famous work, Summa Theologica, and wrote a variety of other works like his unfinished Compendium Theologiae and Responsio ad fr. Ioannem Vercellensem de articulis 108 sumptis ex opere Petri de Tarentasia (Reply to Brother John of Vercelli Regarding 108 Articles Drawn from the Work of Peter of Tarentaise). In his position as head of the studium, conducted a series of important disputations on the power of God, which he compiled into his De potentia.

In 1268 the Dominican Order assigned Aquinas to be regent master at the University of Paris for a second time, a position he held until the spring of 1272. Part of the reason for this sudden reassignment appears to have arisen from the rise of "Averroism" or "radical Aristotelianism" in the universities. In response to these perceived evils, Aquinas wrote two works, one of them being De unitate intellectus, contra Averroistas (On the Unity of Intellect, against the Averroists) in which he blasts Averroism as incompatible with Christian doctrine. During his second regency, he finished the second part of the Summa and wrote De virtutibus and De aeternitate mundi, the latter of which dealt with controversial Averroist and Aristotelian beginninglessness of the world.

Disputes with some important Franciscans such as Bonaventure and John Peckham conspired to make his second regency much more difficult and troubled than the first. A year before Aquinas re-assumed the regency at the 1266-67 Paris disputations, Franciscan master William of Baglione accused Aquinas of encouraging Averroists, calling him the "blind leader of the blind". Aquinas called these individuals the murmurantes (Grumblers). In reality, Aquinas 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.

On 10 December 1270, the bishop of Paris, Etienne Tempier, issued an edict condemning thirteen Aristotlelian and Averroistic propositions as heretical and excommunicating anyone who continued to support them. Many in the ecclesiastical community, the so-called Augustinians, were fearful that this introduction of Aristotelianism and the more extreme Averroism might somehow contaminate the purity of the Christian faith. In what appears to be an attempt to counteract the growing fear of Aristotelian thought, Aquinas conducted a series of disputations between 1270 and 1272: De virtutibus in communi (On Virtues in General), De virtutibus cardinalibus (On Cardinal Virtues), De spe (On Hope).

In 1272 Aquinas took leave from the University of Paris when the Dominicans from his home province called upon him to establish a studium generale wherever he liked and staff it as he pleased. He chose to establish the institution in Naples, and moved there to take his post as regent master. He took his time at Naples to work on the third part of the Summa while giving lectures on various religious topics. On 6 December 1273 Aquinas was celebrating the Mass of St Nicholas when he heard Jesus talk to him. Jesus asked him what he wanted due to his good deeds, but he replied "Only you Lord. Only you." Because of what he saw, he abandoned his routine and refused to dictate to his socius Reginald of Piperno. When Reginald begged him to get back to work, Aquinas replied: "Reginald, I cannot, because all that I have written seems like straw to me." (mihi videtur ut palea). What exactly triggered Aquinas' change in behavior is believed to be some kind of spiritual experience. After taking to his bed, he did recover some strength.

Looking to find a way to reunite the Eastern Orthodox churches with the Catholic Church (the Eastern Orthodox and Roman Catholic churches had separated in 1054 A.D.) Pope Gregory X convened the Second Council of Lyon to be held on 1 May 1274 and summoned Aquinas to attend. At the meeting, Aquinas' work for Pope Urban IV concerning the Greeks, Contra errores graecorum, was to be presented. On his way to the Council, riding on a donkey along the Appian Way, he struck his head on the branch of a fallen tree and became seriously ill again. He was then quickly escorted to Monte Cassino to convalesce. After resting for a while, he set out again, but stopped at the Cistercian Fossanova Abbey after again falling ill. The monks nursed him for several days, and as he received his last rites he prayed: "I receive Thee, ransom of my soul. For love of Thee have I studied and kept vigil, toiled, preached and taught..." He died on 7 March 1274 while giving commentary on the Song of Songs.

In 1277, the same bishop of France, Etienne Tempier, who had issued the condemnation of 1270 issued another, more extensive condemnation. One aim of this condemnation was to clarify that God's absolute power transcended any principles of logic that Aristotle or Averroes might place on it. More specifically, it contained a list of 219 propositions that the bishop had determined to violate the omnipotence of God, and included in this list were twenty Thomistic propositions. Their inclusion badly damaged Aquinas' reputation for many years.

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 asserts that Aquinas died by poisoning, on the order of Charles of Anjou; Villani (ix. 218) cites this belief, and the Anonimo Fiorentino describes the crime and its motive. But the historian Ludovico Antonio Muratori reproduces the account made by one of Aquinas' friends, and this version of the story gives no hint of foul play.

Fifty years after the death of Aquinas, Pope John XXII, seated in Avignon, pronounced Thomas a saint. Aquinas' theology had begun its rise to prestige. Two centuries later, in 1567, Pope Pius V proclamied St. Thomas Aquinas a Doctor of the Church and ranked his feast with those of the four great Latin fathers: Ambrose, Augustine of Hippo, 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 Church. Even though Duns Scotus was more consulted than Thomas at the Council of Trent, Aquinas had the honor of having his Summa Theologica placed on the altar alongside the Bible and the Decretals.

In his encyclical of 4 August 1879, Pope Leo XIII stated that Aquinas' 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' 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 Basilique de Saint-Sernin, Toulouse. In 1974, they were returned to the Church of the Jacobins, where they have remained ever since.

In the General Roman Calendar of 1962,in the Roman Catholic Church, Aquinas was commemorated on 7 March, the day of death. However, in the General Roman Calendar of 1969, even though the norm in the Roman Catholic Church is to remember saints on the day of their death, Aquinas' memorial was transferred to 28 January, the date of the translation of his relics to Toulouse.

Aquinas is honored with a feast day on the liturgical of the Episcopal Church in the United States of America on January 28.

By profession, Aquinas was a theologian rather than a philosopher. Indeed he nowhere characterizes himself as a philosopher, and the references to philosophers found in his own work refer to pagans rather than Christians. He was, nonetheless, a masterfully skilled philosopher. Much of his work bears upon philosophical topics, and in this sense may be characterized as philosophical. Aquinas' philosophical thought has exerted enormous influence on subsequent Christian theology, especially that of the Roman Catholic Church, extending to Western philosophy in general. Aquinas stands as a vehicle and modifier of Aristotelianism, Augustinian Neoplatonism and Proclean Neoplatonism.

Commentaries on Aristotle

Aquinas wrote several important commentaries on Aristotle, including On the Soul, Nicomachean Ethics and Metaphysics. His work is associated with William of Moerbeke's translations of Aristotle from Greek into Latin.

Epistemology

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." However, he believed that human beings have the natural capacity to know many things without special divine revelation, even though such revelation occurs from time to time, "especially in regard to [topics of] faith."

Revelation

Aquinas believed that truth is known through reason (natural revelation) and faith (supernatural revelation). Supernatural revelation has its origin in the inspiration of the Holy Spirit and is made available through the teaching of the prophets, summed up in Holy Scripture, and transmitted by the Magisterium, the sum of which is called "Tradition". Natural revelation is the truth available to all people through their human nature; certain truths all men can attain from correct human reasoning. For example, he felt this applied to rational ways to know the existence of God.

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 (such as the Trinity). In Aquinas' 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 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.

Creation

Aquinas believed life could form from non living material or plant life, a theory of ongoing abiogenesis known as spontaneous generation:

Since the generation of one thing is the corruption of another, it was not incompatible with the first formation of things, that from the corruption of the less perfect the more perfect should be generated. Hence animals generated from the corruption of inanimate things, or of plants, may have been generated then.

Additionally, Aquinas considered Empedocles' theory that various mutated species emerged at the dawn of Creation. Aquinas reasoned that these species were generated through mutations in animal sperm, and argued that they were not unintended by nature; rather, such species were simply not intended for perpetual existence. This discussion is found in his commentary on Aristotle's Physics:

The same thing is true of those substances which Empedocles said were produced at the beginning of the world, such as the ‘ox-progeny’, i.e., half ox and half man. For if such things were not able to arrive at some end and final state of nature so that they would be preserved in existence, this was not because nature did not intend this [a final state], but because they were not capable of being preserved. For they were not generated according to nature, but by the corruption of some natural principle, as it now also happens that some monstrous offspring are generated because of the corruption of seed.

Ethics

Aquinas's ethics are based on the concept of "first principles of action." In his Summa Theologica, he wrote:

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:

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":

The desires to live and to procreate are counted by Aquinas among those basic (natural) human values on which all human values are based. However, Aquinas was vehemently opposed to non-procreative sexual activity. This lead him to view masturbation, oral sex, and even coitus interruptus, as being worse than incest and rape when the act itself is considered (apart from the abuse suffered by the violated party). He also objected to sexual positions other than the missionary position, on the assumption that they made conception more difficult.

Human law is positive law: the natural law applied by governments to societies. Divine law is the specially revealed law in the scriptures.

Aquinas also greatly influenced Catholic understandings of mortal and venial sins.

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 contributed to economic thought as an aspect of ethics and justice. He dealt with the concept of a just price, normally its market price or a regulated price sufficient to cover seller costs of production. He argued it was immoral for sellers to raise their prices simply because buyers were in pressing need for a product.

Aquinas viewed theology, or the sacred doctrine, as a science, the raw material data of which consists of written scripture and the tradition of the Catholic Church. These sources of data were produced by the self-revelation of God to individuals and groups of people throughout history. Faith and reason, while distinct but related, are the two primary tools for processing the data of theology. Aquinas believed both were necessary ... or, rather, that the confluence of both was necessary ... for one to obtain true knowledge of God. Aquinas 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. According to Aquinas, God reveals himself through nature, so to study nature is to study God. The ultimate goals of theology, in Aquinas’ mind, are to use reason to grasp the truth about God and to experience salvation through that truth.

Nature of God

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 quinque 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:

1. God is simple, without composition of parts, such as body and soul, or matter and form.
2. God is perfect, lacking nothing. That is, God is distinguished from other beings on account of God's complete actuality.
3. God is infinite. That is, God is not finite in the ways that created beings are physically, intellectually, and emotionally limited. This infinity is to be distinguished from infinity of size and infinity of number.
4. God is immutable, incapable of change on the levels of God's essence and character.
5. God is one, without diversification within God's self. The unity of God is such that God's essence is the same as God's existence. In Aquinas's words, "in itself the proposition 'God exists' is necessarily true, for in it subject and predicate are the same."

In this approach, he is following, among others, the Jewish philosopher Maimonides.

Following St. Augustine of Hippo, Aquinas defines sin as "a word, deed, or desire, contrary to the eternal law." In other words, anything that disobeys God's will is said to be a sin, and is synonymous with "evil" (privation of good, or privatio boni).

Nature of the Trinity

Aquinas argued that God, while perfectly united, also is perfectly described by Three Interrelated Persons. These three persons (Father, Son, and Holy Spirit) are constituted by their relations within the essence of God. The Father generates the Son (or the Word) by the relation of self-awareness. This eternal generation then produces an eternal Spirit "who enjoys the divine nature as the Love of God, the Love of the Father for the Word."

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.

Prima Causa - First Cause

Aquinas' five proofs for the existence of God take some of Aristotle's assertions concerning principles of being. For Aquinas, God as Prima Causa (first cause) comes from Aristotle's concept of the Unmoved Mover and asserts that God is the ultimate cause of all things.

Nature of Jesus Christ

In the Summa Theologica, Aquinas begins his discussion of Jesus Christ by recounting the biblical story of Adam and Eve and by describing the negative effects of original sin. The purpose of Christ's Incarnation was to restore human nature by removing "the contamination of sin", which humans cannot do by themselves. "Divine Wisdom judged it fitting that God should become man, so that thus one and the same person would be able both to restore man and to offer satisfaction." Aquinas argued in favor of the satisfaction view of atonement; that is, that Jesus Christ died "to satisfy for the whole human race, which was sentenced to die on account of sin."

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 Son of God was merely conjoined to the man 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. 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.

Echoing Athanasius of Alexandria, he said that "The only begotten Son of God...assumed our nature, so that he, made man, might make men gods."

Goal of human life

In Aquinas's thought, the goal of human existence is union and eternal fellowship with God. Specifically, this goal is achieved through the beatific vision, an event in which a person experiences perfect, unending happiness by seeing the very essence of God. This vision, which occurs after death, is a gift from God given to those who have experienced salvation and redemption through Christ while living on earth.

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.

Treatment of heretics

Thomas Aquinas belonged to the Ordo Praedicatorum (commonly known as the Dominicans), whose primary goal is the peaceful conversion of the Albigensian heretics. In the Summa Theologica, he wrote:

With regard to heretics two points must be observed: one, on their own side; the other, on the side of the Church. On their own side there is the sin, whereby they deserve not only to be separated from the Church by excommunication, but also to be severed from the world by death. For it is a much graver matter to corrupt the faith which quickens the soul, than to forge money, which supports temporal life. Wherefore if forgers of money and other evil-doers are forthwith condemned to death by the secular authority, much more reason is there for heretics, as soon as they are convicted of heresy, to be not only excommunicated but even put to death.

On the part of the Church, however, there is mercy which looks to the conversion of the wanderer, wherefore she condemns not at once, but "after the first and second admonition," as the Apostle directs: after that, if he is yet stubborn, the Church no longer hoping for his conversion, looks to the salvation of others, by excommunicating him and separating him from the Church, and furthermore delivers him to the secular tribunal... ( Summa, II-II, Q.11, art.3.)

Heresy was against the secular law in most European countries of the 13th century. Aquinas' suggestion specifically demands that heretics be handed to a "secular tribunal" rather than magisterial authority. That Aquinas specifically says that heretics "deserve... death" is concerning his theology, where all sinners do not deserve life ("For the wages of sin is death; but the free gift of God is eternal life in Christ Jesus our Lord"). He elaborates on his opinion regarding heresy in the next article, when he says:

In God's tribunal, those who return are always received, because God is a searcher of hearts, and knows those who return in sincerity. But the Church cannot imitate God in this, for she presumes that those who relapse after being once received, are not sincere in their return; hence she does not debar them from the way of salvation, but neither does she protect them from the sentence of death. ( Summa, op. cit., art.4.)

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 "sense of duty" (called 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.

In recent years, the cognitive neuroscientist Walter Freeman proposes that Thomism is the philosophical system explaining cognition that is most compatible with neurodynamics, in a 2008 article in the journal Mind and Matter entitled "Nonlinear Brain Dynamics and Intention According to Aquinas."

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).

The pioneer of neurodynamics, cognitive neuroscientist Walter Freeman, considers the work of Aquinas important in remodeling intentionality, the directedness of the mind toward what it is aware of.

For centuries there have been recurring claims that Aquinas had the ability to levitate. 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."

• A discussion of Aquinas on BBC Radio 4's In Our Time series 2009
• Paterson, Craig & Matthew S. Pugh (eds.), Analytical Thomism: Traditions in Dialogue. Ashgate, 2006. Introduction to Thomism

Biographies

• St. Thomas Aquinas biography from Fr. Alban Butler's Lives of the Saints
• An Aquinas Bibliography
• St. Thomas Aquinas biography by Jacques Maritain
• St. Thomas Aquinas biography by G. K. Chesterton protected by copyright outside Australia

On Aquinas

• On the legend of St. Albert's automaton
• Aquinas on Intelligent Extra-Terrestrial Life
• Poetry of St. Thomas Aquinas
• Biography and ideas at SWIF/University of Bari/Italy
• Aquinas's Moral, Political and Legal Philosophy
• Thomas Aquinas at Find A Grave
• Thomistic Philosophy Inspired by the enduring thought of Saint Thomas Aquinas
• Article on Thomism by the Jacques Maritain Center of Notre Dame University
• Thomistica.net news and newsletter devoted to the academic study of Aquinas
• Aquinas 101: A Basic Introduction to the Thought of Saint Thomas Aquinas published by Ave Maria Press
• Aquinas the Scholar from The Thirteenth, the Greatest of Centuries, ch. XVII. by James Joseph Walsh

By Aquinas

• Complete works of St. Thomas Aquinas
• Corpus Thomisticum - his complete works
• Documenta Catholica Omnia - his complete works in PDF
• Summa contra Gentiles
• Summa Theologica
• The Principles of Nature
• On Being and Essence ()
• Catena Aurea (partial)
• Bibliotheca Thomistica IntraText: texts, concordances and frequency lists
• St Thomas' Multilanguage Opera Omnia
• Thomas Aquinas in English
• De Magistro (On the teacher q. 11, a.1 of de Veritate)

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