The Philosophy of Law: Private Right, § 14: The Juridical Act of This Original Acquisition Is Occupancy
The Act of taking possession (appreliensio), as being at its beginning the physical appropriation of a corporeal thing in space (possession™ physiccc}, can accord with the Law of the external Freedom of all, under no other condition than that of its Priority in respect of Time. In this relation it must have the characteristic of a first net in the way of taking possession, as a free exercise of Will. The activity of Will, however, as determining that the thing—in this case a definite separate place on the surface of the Earth—shall be mine, being an act of Appropriation, cannot be otherwise in the case of original Acquisition than individual or unilateral (voluntas uni-lateralis s. propria). Now, OCCUPANCY is the Acquisition of an external object by an individual act of Will., The original Acquisition of such an object as a limited portion of the Soil, can therefore only be accomplished by an act of Occupation.
The possibility of this mode of Acquisition cannot be intuitively apprehended by pure Reason in any way, nor established by its Principles, but is an immediate conse quence from the Postulate of the Practical Reason. The Will as practical Reason, however, cannot justify external Acquisition otherwise than only in so far as it is itself included in an absolutely authoritative Will, with which it is united by implication; or, in other words, only in so far as it is contained within a union of the Wills of all who come into practical relation with each other. For an individual, unilateral Will—and the same applies to a Dual or other particular Will—cannot impose on all an Obligation which is contingent in itself. This requires an omnilateral or universal Will, which is not contingent, but a priori, and which is therefore necessarily united and legislative. Only in accordance with such a Principle can there be agreement of the active free-will of each individual with the freedom of all, and consequently Rights in general, or even the possibility of an external Mine and Thine.