The new phase in the development of the Church’s political theology, which Pope Leo XIII introduced toward the end of the 1870s, confirms the papal see’s attempts to free itself from its defensive and judgmental attitude to modern society. Thomistic social philosophy and political ethics was held up as an alternative. And this was indeed an alternative based on an ontological foundation which could win out over both modern liberalism and the socially destructive individualistic liberation ideology. Thomistic ontology, which had been enshrined in the late Scholastic understanding of theology, could – in the view of the papal see – provide a sustainable rational foundation for both politics and culture, including the sciences, which now represented what was seen as a (scientistic) outlook. What later would be called the Leonine program was an ambitious attempt to bring the Church out of the cultural backwaters.