Rerum novarum (from its incipit, with the direct translation of the Latin meaning "of revolutionary change"), or Rights and Duties of Capital and Labor, is an encyclical issued by Pope Leo XIII on 15 May 1891. It is an open letter, passed to all Catholic patriarchs, primates, archbishops and bishops, that addressed the condition of the working classes. It discusses the relationships and mutual duties between labor and capital, as well as government and its citizens.
https://en.wikipedia.org/wiki/Rerum_novarum