Pope Pius XI
Quadragesimo Anno §147
Quadragesimo Anno: On Reconstruction of the Social Order
147 Surely there is not one that does not know how many and how great are the works that the tireless zeal of Catholics is striving everywhere to carry out, both for social and economic welfare as well as in the fields of education and religion. But this admirable and unremitting activity not infrequently shows less effectiveness because of the dispersion of its energies in too many different directions. Therefore, let all men of good will stand united, all who under the Shepherds of the Church wish to fight this good and peaceful battle of Christ; and under the leadership and teaching guidance of the Church let all strive according to the talent, powers, and position of each to contribute something to the Christian reconstruction of human society which Leo XIII inaugurated through his immortal Encyclical, On the Condition of Workers , seeking not themselves and their own interests, but those of Jesus Christ, not trying to press at all costs their own counsels, but ready to sacrifice them, however excellent, if the greater common good should seem to require it, so that in all and above all Christ may reign, Christ may command to Whom be "honor and glory and dominion forever and ever."
Source: Quadragesimo Anno (Vatican.va)