8 The fact that God has given the earth for the use and enjoyment of the whole human race can in no way be a bar to the owning of private property. For God has granted the earth to mankind in general, not in the sense that all without distinction can deal with it as they like, but rather that no part of it was assigned to any one in particular, and that the limits of private possession have been left to be fixed by man's own industry, and by the laws of individual races. Moreover, the earth, even though apportioned among private owners, ceases not thereby to minister to the needs of all, inasmuch as there is not one who does not sustain life from what the land produces. Those who do not possess the soil contribute their labor; hence, it may truly be said that all human subsistence is derived either from labor on one's own land, or from some toil, some calling, which is paid for either in the produce of the land itself, or in that which is exchanged for what the land brings forth.
Source: Rerum Novarum (Vatican.va)