45 First, then, let it be considered as certain and established that neither Leo nor those theologians who have taught under the guidance and authority of the Church have ever denied or questioned the twofold character of ownership, called usually individual or social according as it regards either separate persons or the common good. For they have always unanimously maintained that nature, rather the Creator Himself, has given man the right of private ownership not only that individuals may be able to provide for themselves and their families but also that the goods which the Creator destined for the entire family of mankind may through this institution truly serve this purpose. All this can be achieved in no wise except through the maintenance of a certain and definite order.
Source: Quadragesimo Anno (Vatican.va)