Pope Pius XI
Quadragesimo Anno §145
Quadragesimo Anno: On Reconstruction of the Social Order
145 To ward off such great evils from human society nothing, therefore, is to be left untried; to this end may all our labors turn, to this all our energies, to this our fervent and unremitting prayers to God! For with the assistance of Divine Grace the fate of the human family rests in our hands.
Source: Quadragesimo Anno (Vatican.va)