In confirmation of the theory that all objects of the senses are mere phenomena, the fact is adduced that (with the exception of the will and the feelings, which are not cognitions) nothing is given us through the senses but representations of relations, while a thing in itself cannot be known by mere relations.  The phenomenon is a sum total of mere relations.  In regard to matter we know only extension, motion, and the laws of this motion or forces (attraction, repulsion, impenetrability), but all these are merely relations of the thing to something, else, that is, external relations.  Where is the inner side which underlies this exterior, and which belongs to the object in itself?  This is never to be found in the phenomenon, and no matter how far the observation and analysis of nature may advance (a work with unlimited horizons!) they reach nothing but portions of space occupied by matter and effects which matter exercises, that is, nothing beyond that which is comparatively internal, and which, in its turn, consists of external relations.  The absolutely inner side of matter is a mere fancy; and if the complaint that the “inner side” of things is concealed from us is to mean that we do not comprehend what the things which appear to us may be in themselves, it is unjust and irrational, for it demands that we should be able to intuit without senses, in other words, that we should be other than men.  The transcendent questions concerning the noumenon of things are unanswerable; we know ourselves, even, only as phenomena!  A phenomenon consists in nothing but the relation of something in general to the senses.

It is indubitable that something corresponds to phenomena, which, by affecting our sensibility, occasions sensations in us, and thereby phenomena.  The very word, the very concept, “phenomenon”, indicates a relation to something which is not phenomenon, to an object not dependent on the sensibility. What this may be continues hidden from us, for knowledge is impossible without intuition.  Things in themselves are unknowable.  Nevertheless the idea (it must be confessed, the entirely empty idea) of this “transcendental object”, as an indeterminate somewhat = x which underlies phenomena, is not only allowable, but, as a limiting concept, unavoidable in order to confine the pretensions of sense to the only field which is accessible to it, that is, to the field of phenomena.

The inference “space and time are nothing but representations and representations are in us, therefore space and time as well as all phenomena in them, bodies with their forces and motions, are in us,” does not accurately express Kant’s position, for he might justly reply that, according to him, bodies as phenomena are in different parts in space from that which we assign to ourselves, and thus without us; that space is the form of external intuition, and through it external objects arise for us from sensations; but that, in regard to the things in themselves which affect us, we are entirely ignorant whether they are within or without us.