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.
Thomas's theology had begun its rise to prestige. Two centuries later, in 1567, Pope Pius V proclaimed 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. At the Council of Trent, Thomas had the honor of having his Summa theologiae placed on the altar alongside the Bible and the Decretals.
The first edition of Thomas's opera omnia, the so-called editio Piana (from Pius V, the Dominican Pope who commissioned it), was produced in 1570 at the studium of the Roman convent at Santa Maria sopra Minerva, the forerunner of the Pontifical University of Saint Thomas Aquinas, Angelicum.
Abbé Migne published an edition of the Summa Theologiae, in four volumes, as an appendix to his Patrologiae Cursus Completus (English editions: Joseph Rickaby 1872, J. M. Ashley 1888).
In his encyclical of 4 August 1879, Aeterni Patris, Pope Leo XIII stated that Thomas Aquinas's theology was a definitive exposition of Catholic doctrine. Thus, he directed the clergy to take the teachings of Thomas as the basis of their theological positions. Leo XIII also decreed that all Catholic seminaries and universities must teach Thomas's doctrines, and where Thomas did not speak on a topic, the teachers were "urged to teach conclusions that were reconcilable with his thinking." In 1880, Saint Thomas Aquinas was declared patron of all Catholic educational establishments.
The critical edition of Thomas's works is the ongoing edition commissioned by Pope Leo XIII (1882–1903), the so-called Leonine Edition. Most of his major works have now been edited, the Summa Theologiae in nine volumes during 1888–1906, the Summa Contra Gentiles in three volumes during 1918–1930.
Thomas's aesthetic theories, especially the concept of claritas, deeply influenced the literary practice of modernist Writer James Joyce, who used to extol Thomas as being second only to Aristotle among Western Philosophers. Joyce refers to Thomas's doctrines in Elementa philosophiae ad mentem D. Thomae Aquinatis doctoris angelici (1898) of Girolamo Maria Mancini, professor of theology at the Collegium Divi Thomae de Urbe. For Example, Mancini's Elementa is referred to in Joyce's Portrait of the Artist as a Young Man.
Henry Adams's Mont Saint Michel and Chartres ends with a culminating chapter on Thomas, in which Adams calls Thomas an "artist" and constructs an extensive analogy between the design of Thomas's "Church Intellectual" and that of the gothic cathedrals of that period. Erwin Panofsky later would echo these views in Gothic Architecture and Scholasticism (1951).
The influence of Thomas's aesthetics also can be found in the works of the Italian semiotician Umberto Eco, who wrote an essay on aesthetic ideas in Thomas (published in 1956 and republished in 1988 in a revised edition).
When he was canonized, his feast day was inserted in the General Roman Calendar for celebration on 7 March, the day of his death. Since this date commonly falls within Lent, the 1969 revision of the calendar moved his memorial to 28 January, the date of the translation of his relics to Church of the Jacobins, Toulouse.
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 titled "Nonlinear Brain Dynamics and Intention According to Aquinas."
Thomas was most probably born in the castle of Roccasecca, located in Aquino, old county of the Kingdom of Sicily (present-day Lazio region, Italy), c. 1225, According to some authors, he was born in the castle of his father, Landulf of Aquino. Though he did not belong to the most powerful branch of the family, Landulf of Aquino was a man of means. As a knight in the Service of King Roger II, he held the title miles. Thomas's mother, Theodora, belonged to the Rossi branch of the Neapolitan Caracciolo family. Landulf's brother Sinibald was abbot of the first Benedictine monastery at Monte Cassino. While the rest of the family's sons pursued military careers, the family intended for Thomas to follow his uncle into the abbacy; this would have been a normal career path for a younger son of southern Italian nobility.
Heresy was a capital offense against the secular law of most European countries of the 13th century, which had a limited prison capacity. Kings and emperors, even those at war with the papacy, listed heresy first among the crimes against the state. Kings claimed power from God according to the Christian faith. Often enough, especially in that age of papal claims to universal worldly power, the rulers' power was tangibly and visibly legitimated directly through coronation by the pope.
A grasp of Thomas's psychology is essential for understanding his beliefs around the afterlife and resurrection. Thomas, following Church doctrine, accepts that the soul continues to exist after the death of the body. Because he accepts that the soul is the form of the body, then he also must believe that the human being, like all material things, is form-matter composite. Substantial form (the human soul) configures prime matter (the physical body) and is the form by which a material composite belongs to that species it does; in the case of human beings, that species is rational animal. So, a human being is a matter-form composite that is organized to be a rational animal. Matter cannot exist without being configured by form, but form can exist without matter—which allows for the separation of soul from body. Thomas says that the soul shares in the material and spiritual worlds, and so has some features of matter and other, immaterial, features (such as access to universals). The human soul is different from other material and spiritual things; it is created by God, but also only comes into existence in the material body.