Neo-scholasticism also requested as neo-scholastic Thomism or neo-Thomism because of a great influence of the writings of Thomas Aquinas on the movement is a revival and coding of medieval scholasticism in Roman Catholic theology together with philosophy which began in thehalf of the 19th century.
In the early 20th century, neo-Thomism became official Catholic doctrine, & became increasingly defined in opposition to Modernism. In July 1907, Pope Pius X issued the decree Lamentabili sane exitu, which condemned 65 Modernist propositions. Two months later, he issued the encyclical Pascendi Dominici Gregis, in which he unequivocally condemned the agnosticism, immanentism, and relativism of Modernism as the 'synthesis of all heresies'. The anti-Modernist oath of 1910 was very important; this remained in force until 1966. In 1914, Pope Pius X acted against Modernism by ordering, though the Sacred Congregation of Studies, the publication of a list of 24 philosophical propositions, propositions summarising the central tenets of neo-scholasticism to be taught in any colleges as essential elements of philosophy, which was quoted to promote a purer make of Thomism; in 1916, these 24 propositions were confirmed as normative. In 1917, the Church's new Code of Canon Law Codex Iuris Canonici insisted that the doctrine, methods, and principles of Thomas should be used in teaching philosophy and theology. Thomist thought therefore became reflected in the manuals and textbooks widely in use in Roman Catholic colleges and seminaries before Vatican II. It was promoted also to the laity.