 The influence of the movement was important as a counterpoint to the widespread neo-scholasticism of Catholic thought, especially through its influence on the reforms initiated at the Second Vatican Council.In the late nineteenth and first half of the twentieth century (especially after the issuing of the encyclical "Aeterni Patris" by Pope Leo XIII in 1879), Roman Catholic thought was dominated by neo-scholastic forms of thought.This, in reaction against modernist theology, insisted on a rigid adherence to the thought, methods and principles of the 13th-century thinker Thomas Aquinas.