Natural Law and Possession According to the Catholic Church: Pope John Paul II (1987)

It is necessary to state once more the characteristic principle of Christian social doctrine: the goods of this world are originally meant for all. The right to private property is valid and necessary, but it does not nullify the value of this principle. Private property, in fact, is under a "social mortgage," which means that it has an intrinsically social function, based upon and justified precisely by the principle of the universal destination of goods.

Sollicitudo Rei Socialis, encyclical, On Social Concern,John Paul II, December 30, 1987, 42.