34 But although all citizens, without exception, can and ought to contribute to that common good in which individuals share so advantageously to themselves, yet it should not be supposed that all can contribute in the like way and to the same extent. No matter what changes may occur in forms of government, there will ever be differences and inequalities of condition in the State. Society cannot exist or be conceived of without them. Some there must be who devote themselves to the work of the commonwealth, who make the laws or administer justice, or whose advice and authority govern the nation in times of peace, and defend it in war. Such men clearly occupy the foremost place in the State, and should be held in highest estimation, for their work concerns most nearly and effectively the general interests of the community. Those who labor at a trade or calling do not promote the general welfare in such measure as this, but they benefit the nation, if less directly, in a most important manner. We have insisted, it is true, that, since the end of society is to make men better, the chief good that society can possess is virtue. Nevertheless, it is the business of a well-constituted body politic to see to the provision of those material and external helps "the use of which is necessary to virtuous action."(28) Now, for the provision of such commodities, the labor of the working class - the exercise of their skill, and the employment of their strength, in the cultivation of the land, and in the workshops of trade - is especially responsible and quite indispensable. Indeed, their co-operation is in this respect so important that it may be truly said that it is only by the labor of working men that States grow rich. Justice, therefore, demands that the interests of the working classes should be carefully watched over by the administration, so that they who contribute so largely to the advantage of the community may themselves share in the benefits which they create-that being housed, clothed, and bodily fit, they may find their life less hard and more endurable. It follows that whatever shall appear to prove conducive to the well-being of those who work should obtain favorable consideration. There is no fear that solicitude of this kind will be harmful to any interest; on the contrary, it will be to the advantage of all, for it cannot but be good for the commonwealth to shield from misery those on whom it so largely depends for the things that it needs.
Source: Rerum Novarum (Vatican.va)