Thomism is the philosophical school that arose as a legacy of the work and thought of Saint
Thomas Aquinas (1225–1274), philosopher, theologian, and Doctor of the Church. In philosophy, his
disputed questions and commentaries on
Aristotle are perhaps his most well-known works. In theology, his
Summa Theologica is one of 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 encyclical
Doctoris Angelici Pope Pius X cautioned that the teachings of the Church cannot be understood without the basic philosophical underpinnings of Thomas' major theses:
The
Second Vatican Council described Thomas's system as the "Perennial Philosophy".