Summa Theologica in the context of "Divine Comedy"

Thomism is the philosophical and theological school which arose as a legacy of the work and thought of Thomas Aquinas (1225–1274), the Dominican philosopher, theologian, and Doctor of the Church.

In philosophy, Thomas's disputed questions and commentaries on Aristotle are perhaps his best-known works. In theology, his Summa Theologica is amongst the most influential documents in medieval theology and continues to be the central point of reference for the philosophy and theology of the Catholic Church. In the 1914 motu proprio Doctoris Angelici, Pope Pius X cautioned that the teachings of the Church cannot be understood without the basic philosophical underpinnings of Thomas's major theses:

The Quinque viæ (Latin for "Five Ways") (sometimes called the "five proofs") are five logical arguments for the existence of God summarized by the 13th-century Catholic philosopher and theologian Thomas Aquinas in his book Summa Theologica. They are:

1. the argument from "first mover";
2. the argument from universal causation;
3. the argument from contingency;
4. the argument from degree;
5. the argument from final cause or ends ("teleological argument").

Aquinas expands the first of these – God as the "unmoved mover" – in his Summa Contra Gentiles.

The Fruit of the Holy Spirit (sometimes referred to as the Fruits of the Holy Spirit) is a biblical term that sums up nine attributes of a person or community living in accord with the Holy Spirit, according to chapter 5 of the Epistle to the Galatians: "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control." The fruit is contrasted with the works of the flesh discussed in the previous verses."These qualities are the result of the work of the Holy Spirit in a Christian's life."[1] Galatians 5:22–23 (New International Version).

The Catholic Church follows the Latin Vulgate version of Galatians in recognizing twelve attributes of the Fruit: charity (caritas), joy (gaudium), peace (pax), patience (patientia), benignity (benignitas), goodness (bonitas), longanimity (longanimitas), mildness (mansuetudo), faith (fides), modesty (modestia), continency (continentia), and chastity (castitas). This tradition was defended by Thomas Aquinas in his work Summa Theologica, and reinforced in numerous Catholic catechisms, including the Baltimore Catechism, the Penny Catechism, and the Catechism of the Catholic Church.

Treatise on Law is Thomas Aquinas' major work of legal philosophy. It forms questions 90–108 of the Prima Secundæ ("First [Part] of the Second [Part]") of the Summa Theologiæ, Aquinas' masterwork of Scholastic philosophical theology. Along with Aristotelianism, it forms the basis not only for the legal theory of Catholic canon law, but provides a model for natural law theories generally.