§ 18. Judgments of experience are empirical judgments that are valid for external objects. They require special pure concepts which have originated in the pure understanding. All judging subjects will agree on their experience of the object. When a perception is subsumed under these pure concepts, it is changed into objective experience. On the other hand, all empirical judgments that are only valid for the one judging subject are judgments of mere perception. These judgments of perception are not subsumed under a pure concept of the understanding.