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)
Source: Rerum Novarum (Vatican.va)