States began to be established, and so two categories were made of the things which had been wrested away from early ownership in common. For some things were public, that is, were the property of the people (which is the real meaning of that expression), while other things were private, that is, were the property of individuals. Ownership, however, both public and private, arises in the same way . . . Two conclusions may be drawn from what has thus far been said. The first is, that that which cannot be occupied, or which never has been occupied, cannot be the property of any one, because all property has arisen from occupation. The second is, that all that which has been so constituted by nature that although serving some one person it still suffices for the common use of all other persons, is today and ought in perpetuity to remain in the same condition as when it was first created by nature . . . things which are called “public” are, according to the Laws of the law of nations, the common property of all, and the private property of none. The air belongs to this class of things for two reasons. First, it is not susceptible of occupation; and second its common use is destined for all men. For the same reasons the sea is common to all, because it is so limitless that it cannot become a possession of any one, and because it is adapted for the use of all.