Pope Pius XI
Quadragesimo Anno §33
Quadragesimo Anno: On Reconstruction of the Social Order
33 To the founding of these associations the clergy and many of the laity devoted themselves everywhere with truly praiseworthy zeal, eager to bring Leo's program to full realization. Thus associations of this kind have molded truly Christian workers who, in combining harmoniously the diligent practice of their occupation with the salutary precepts of religion, protect effectively and resolutely their own temporal interests and rights, keeping a due respect for justice and a genuine desire to work together with other classes of society for the Christian renewal of all social life.
Source: Quadragesimo Anno (Vatican.va)