The material of intuition and thought is given to the soul, received by it; it arises through the action of objects upon the senses, and is always empirical.  Intuition is the only organ of reality; in sensation the presence of a real object as the cause of the sensation is directly revealed.  When Kant’s transcendental idealism was placed by a reviewer on a level with the empirical idealism of Berkeley, which denies the existence of the external world, he distinctly asserted that it had never entered his mind to question the reality of external things.  Further, after the existence of real things affecting the senses had been transformed in his mind from a basis of the investigation into an object of inquiry, he endeavored to defend this assumption (which at first he had naively borrowed from the realism of pre-scientific thought) by arguments, but without any satisfactory result.[1]

[Footnote 1:  The task of confirming the existence of things in themselves changes under his hands into another, that of proving the existence of external phenomena.  “That external objects are real as representations” Berkeley had never disputed.]

On the basis of the inseparability of sensibility and understanding the ideal of knowledge—­an extension of knowledge to be attained by a priori means (p. 333)—­experiences a remarkable addition in the position that the rational synthesis thus obtained must be a knowledge of reality, must be applied to matter given in intuition.  To the question, “How are synthetic judgments a priori possible?” is joined a second equally legitimate inquiry, “How do they become objectively valid, or applicable to objects of experience?” The principle from which their validity is proved—­they are applicable to objects of experience because without them experience would not be possible, because they are conditions of experience—­like the criterion of apriority (strict universality and necessity), is one of the noetic assumptions of the critical theory.[1]

[Footnote 1:  Cf.  Vaihinger, Kommentar, i. pp. 425-430.]

Inasmuch as its investigation relates to the conditions of experience the Kantian criticism follows a method which it itself terms transcendental.  Heretofore, when the metaphysical method had been adopted, the object had been the suprasensible; and when knowledge had been made the object of investigation, the method followed had been empirical, psychological.  Kant had the right to consider himself the creator of noetics, for he showed it the transcendental point of view.  Knowledge is an object of experience, but its conditions are not.  The object is to explain knowledge, not merely to describe it psychologically,—­to establish a new science of knowledge from principles, from pure reason.  That which lies beyond experience is sealed from our thought; that which lies on this side of it is still uninvestigated, though capable and worthy of investigation, and in extreme need thereof.  Criticism forbids the transcendent use of reason (transcending experience); it permits, demands, and itself exercises the transcendental[1] use of it, which explains an experiential object, knowledge, from its conditions, which are not empirically given.