The Philosophy of Law: Private Right, § 20: What Is Acquired by Contract?
But what is that, designated as ‘External,’ which I acquire by Contract? As it is only the Causality of the active Will of another, in respect of the Performance of something promised to me, I do not immediately acquire thereby an external Thing, but an Act of the Will in question, whereby a Thing is brought under my power so that I make it mine.—By the Contract, there fore, I acquire the Promise of another, as distinguished from the Thing promised; and yet something is thereby added to my Having and Possession. I have become the richer in possession (locuplctior) by the Acquisition of an active Obligation that I can bring to bear upon the Freedom and Capability of another.—This my Right, however, is only a personal Right, valid only to the effect of acting upon a particular physical Person and specially upon the Causality of his Will, so that he shall perform something for me. It is not a Real Right upon that Mural Person, which is identified with the Idea of the united Will of All viewed a priori, and through which alone I can acquire a Right valid against every Possessor of the Tkinfj. For, it is in this that all Right in a T/tiny consists.
The Transfer or transmission of what is mine to another by Contract, takes place according to the Law of Continuity (Lex Continui). Possession of the object is not interrupted for a moment during this Act; for, otherwise, I would acquire an object in this state as a Thing that had no Possessor, and it would thus be acquired originally; which is contrary to the idea of a Contract.—This Continuity, however, implies that it is not the particular Will of either the Promiser or the Acceptor, but their united Will in common, that transfers what is mine to another. And hence it is not accomplished in such a manner that the Promiser first relinquishes (derclinquit) his Possession for the benefit of another, or renounces his Right (renunciat), and thereupon the other at the same time enters upon it; or conversely. The Trans fer (translatio) is therefore an Act in which the object belongs for a moment at the same time to both, just as in the parabolic path of a projectile the object on reaching its highest point may be regarded for a moment as at the same time both rising and falling, and as thus passing in fact from the ascending to the falling motion.