49 It follows from what We have termed the individual and at the same time social character of ownership, that men must consider in this matter not only their own advantage but also the common good. To define these duties in detail when necessity requires and the natural law has not done so, is the function of those in charge of the State. Therefore, public authority, under the guiding light always of the natural and divine law, can determine more accurately upon consideration of the true requirements of the common good, what is permitted and what is not permitted to owners in the use of their property. Moreover, Leo XIII wisely taught "that God has left the limits of private possessions to be fixed by the industry of men and institutions of peoples." That history proves ownership, like other elements of social life, to be not absolutely unchanging, We once declared as follows: "What divers forms has property had, from that primitive form among rude and savage peoples, which may be observed in some places even in our time, to the form of possession in the patriarchal age; and so further to the various forms under tyranny (We are using the word tyranny in its classical sense); and then through the feudal and monarchial forms down to the various types which are to be found in more recent times." That the State is not permitted to discharge its duty arbitrarily is, however, clear. The natural right itself both of owning goods privately and of passing them on by inheritance ought always to remain intact and inviolate, since this indeed is a right that the State cannot take away: "For man is older than the State," and also "domestic living together is prior both in thought and in fact to uniting into a polity." Wherefore the wise Pontiff declared that it is grossly unjust for a State to exhaust private wealth through the weight of imposts and taxes. "For since the right of possessing goods privately has been conferred not by man's law, but by nature, public authority cannot abolish it, but can only control its exercise and bring it into conformity with the common weal." Yet when the State brings private ownership into harmony with the needs of the common good, it does not commit a hostile act against private owners but rather does them a friendly service; for it thereby effectively prevents the private possession of goods, which the Author of nature in His most wise providence ordained for the support of human life, from causing intolerable evils and thus rushing to its own destruction; it does not destroy private possessions, but safeguards them; and it does not weaken private property rights, but strengthens them.
Source: Quadragesimo Anno (Vatican.va)