The papal encyclical Rerum Novarum is delivered on May 15, 1891, and offers a prospect of a Catholic labour movement. Pope Leo XIII opposes Marxism as well as capitalism with the idea of a corporatist society. In such a society every group would be an essential part of the whole. This is a society in which state power is crucial, and the various social groups are interdependent. Exactly forty years later, on May 15, 1931, the encyclical Quadragesimo Anno by Pius XI elaborates further on this idea. This memorial by the Dutch Roman Catholic workers' foundation appears in that same year.