Rerum Novarum excerpt V:

"17. It must be first of all recognized that the condition of things inherent in human affairs must be borne with, for it is impossible to reduce civil society to one dead level. Socialists may in that intent do their utmost, but all striving against nature is in vain. There naturally exist among mankind manifold differences of the most important kind; people differ in capacity, skill, health, strength; and unequal fortune is a necessary result of unequal condition. Such unequality is far from being disadvantageous either to individuals or to the community. Social and public life can only be maintained by means of various kinds of capacity for business and the playing of many parts; and each man, as a rule, chooses the part which suits his own peculiar domestic condition. As regards bodily labor, even had man never fallen from the state of innocence, he would not have remained wholly idle; but that which would then have been his free choice and his delight became afterwards compulsory, and the painful expiation for his disobedience. "Cursed be the earth in thy work; in thy labor thou shalt eat of it all the days of thy life."(5)

18. In like manner, the other pains and hardships of life will have no end or cessation on earth; for the consequences of sin are bitter and hard to bear, and they must accompany man so long as life lasts. To suffer and to endure, therefore, is the lot of humanity; let them strive as they may, no strength and no artifice will ever succeed in banishing from human life the ills and troubles which beset it. If any there are who pretend differently - who hold out to a hard-pressed people the boon of freedom from pain and trouble, an undisturbed repose, and constant enjoyment - they delude the people and impose upon them, and their lying promises will only one day bring forth evils worse than the present. Nothing is more useful than to look upon the world as it really is, and at the same time to seek elsewhere, as We have said, for the solace to its troubles.

5). Gen. 3:17.