Quadragesimo Anno §2

² Other Encyclicals of Our Predecessor had in a way prepared the path for that outstanding document and proof of pastoral care: namely, those on the family and the Holy Sacrament of Matrimony as the source of human society, on the origin of civil authority and its proper relations with the Church, on the chief duties of Christian citizens, against the tenets of Socialism against false teachings on human liberty, and others of the same nature fully expressing the mind of Leo XIII. Yet the Encyclical, On the Condition of Workers , compared with the rest had this special distinction that at a time when it was most opportune and actually necessary to do so, it laid down for all mankind the surest rules to solve aright that difficult problem of human relations called "the social question."