Pope Pius XI
Quadragesimo Anno §63
Quadragesimo Anno: On Reconstruction of the Social Order
63 As We have already indicated, following in the footsteps of Our Predecessor, it will be impossible to put these principles into practice unless the non-owning workers through industry and thrift advance to the state of possessing some little property. But except from pay for work, from what source can a man who has nothing else but work from which to obtain food and the necessaries of life set anything aside for himself through practicing frugality? Let us, therefore, explaining and developing wherever necessary Leo XIII's teachings and precepts, take up this question of wages and salaries which he called one "of very great importance."
Source: Quadragesimo Anno (Vatican.va)