18 The Church did not let these rich fountains lie quiescent in her bosom, but from them drew copiously for the common good of the longed-for peace. Leo himself and his Successors, showing paternal charity and pastoral constancy always, in defense especially of the poor and the weak, proclaimed and urged without ceasing again and again by voice and pen the teaching on the social and economic question which On the Condition of Workers presented, and adapted it fittingly to the needs of time and of circumstance. And many bishops have done the same, who in their continual and able interpretation of this same teaching have illustrated it with commentaries and in accordance with the mind and instructions of the Holy See provided for its application to the conditions and institutions of diverse regions.
Source: Quadragesimo Anno (Vatican.va)