On the other hand, many of the ablest theologians of the same period declared that private ownership was enjoined by the natural law and right reason, and consequently that it was among the individual's natural rights. According to St. Thomas Aquinas, private property is "necessary for human life," and is one of those social institutions which are prescribed by the _jus gentium_; and the content of the _jus gentium_ is not determined by positive law, but by the dictates of "natural reason," by "natural reason itself."[45] These statements seem to convey the doctrine of natural right as clearly as could be expected in the absence of an explicit declaration. Cardinal de Lugo sets forth the same teaching somewhat more compactly, but in substantially the same terms: "Speaking generally, a division of goods and of ownership-titles proceeds from the law of nature, for natural reason dictates such division as necessary in the present circumstances of fallen nature and dense populations."[46] This view is to-day universally accepted among Catholic writers. _The Teaching of Pope Leo XIII_ The official teaching of the Church on the subject is found in the Encyclical, "On the Condition of Labour," by Pope Leo XIII. In this document we are told that the proposals of the Socialists are "manifestly against justice"; that the right of private property in land is "granted to man by nature"; that it is derived "from nature not from man, and the State has the right to control its use in the interest of the public good alone, but by no means to abolish it altogether." These statements the Pope deduces from a consideration of man's needs. Private property in land is necessary to satisfy the wants, present and future, of the individual and his family. Were the State to attempt the task of making this provision, it would exceed its proper sphere, and produce manifold domestic and social confusion. While Pope Leo defines the natural right of private ownership as incompatible with complete Socialism, that is, collective use as well as collective ownership, his statements cannot fairly or certainly be interpreted as condemning the Single Tax system, or any other arrangement which would leave to the individual managerial use and secure possession of his holding, together with the power to transmit and transfer it, and full ownership of improvements. These are the only elements of ownership which the Holy Father defends, and which he insists upon as necessary. The one element of private ownership which the Single Tax system would exclude; namely, the power to take rent from and profit by the changes in land values, finds no place among the advantages of private ownership enumerated in the Encyclical.