28 Our predecessor Pius XII—and this redounds to his special credit and praise—exhorted the laity, with eloquent and abundant doctrine and repeated admonitions, willingly and zealously to enter the apostolic field and give their active cooperation to the ecclesiastical hierarchy, in the same way in which, since the times of the early Church and throughout the centuries, the faithful have cooperated with their bishops and their clergy, to enable them to carry out their tasks more easily and with greater efficacy, in religious and social fields. Our times require this effort, not less, nay, even more, since requirements of this kind have grown, and the greatly increased multitudes are hungry for the spiritual food of true doctrine. Indeed, their circumstances have become more difficult and complex. And, wherever the Church fights her peaceful battles, she must be able to count on a complete organization, including not only the different grades of the hierarchy, but also the ranks of the laity proper. It is also necessary that her work of salvation be carried out equally by all. (49)
Source: Princeps Pastorum (Vatican.va)