This chapter explores the origins of Catholic discourses of “revolution” in the writings of Thomas Aquinas and his late nineteenth- and early twentieth-century interpreters. Leo XIII (1878–1903) launched his papacy with a promise of “Thomist renewal.” In response, a generation of Catholic thinkers from across Europe developed their own visions of a just society. French philosopher Jacques Maritain and his Polish counterparts, the priests Władysław Korniłowicz and Antoni Szymański, made a passionate case for the “human person” as a concept rooted in their study of Aquinas’s Summa Theologiae. Their generation confronted powerful currents of integral nationalism in French Action (France) and National Democracy (Poland). Responding to Leo XIII’s 1891 encyclical Rerum Novarum, they attempted to break with the integralist currents—with, at best, limited success. These early Catholic “revolutionaries” included Thomists, social Catholics, and Europe’s first Christian Democrats. In the 1930s, as republics collapsed across Europe and both fascist regimes and the nascent Soviet Union grew in power, the generation of laymen who had studied under Korniłowicz, Maritain, and Szymański began looking for more radical solutions. First and foremost among these budding radicals was Emmanuel Mounier, and it was principally to him that subsequent generations turned.
