Pope John XXIII
Mater et Magistra §240
Mater et Magistra: On Christianity and Social Progress
240 These, then, are the educational principles which must be put into effect. It is a task which belongs particularly to Our sons, the laity, for it is their lot to live an active life in the world and organize themselves for the attainment of temporal ends.
Source: Mater et Magistra (Vatican.va)