With objects of sense this happens through the connection with some perception of mine in accordance with empirical laws; but for objects of pure thinking there is no means whatever for cognizing their existence, because it would have to be cognized entirely a priori, but our consciousness of all existence (whether immediately through perception or through inferences connecting something with perception) belongs entirely and without exception to the unity of experience, and though an existence outside this field cannot be declared absolutely impossible, it is a presupposition that we cannot justify through anything.