If we take the above propositions in a synthetic connection, as valid for all thinking beings, as they must be taken in rational psychology as a system, and if from the category of relation,a starting with the proposition All thinking beings are, as such, substances we go backward through the series propositions until the circle closes, then we finally come up against the existence of thinking beings, which in this system are conscious of themselves not only as independent of external things but also as being able to determine themselves from themselves (in regard to the persistence belonging necessarily to the character of a substance).