Pope Leo XIII Apostolici Muneris, December 28, 1878. As the nature of Our Apostolic office required of Us, We have not omitted, from the very outset of Our Pontificate, addressing you, Venerable Brothers, in Encyclical Letters, in order to advert to the deadly plague which is tainting society to its very core and bringing it… Read More Socialism, Communism, Nihilism: Encyclical Letter. Leo XIII. 1878.