Book I: Metaphysics of Knowledge.
Chapter I: The Spiritual Principle in Knowledge and Nature.
§ 46.
After what has been already said, the answer to these questions need not detain us long. If it is admitted that we know of no other medium but a thinking or self-distinguishing consciousness, in and through which that unification of the manifold can take place which is necessary to constitute relation, it follows that a sensation apart from thought--not determined or acted on by thought--would be an unrelated sensation; and an unrelated sensation cannot amount to a fact. Mere sensation is in truth a phrase that represents no reality. It is the result of a process of abstraction; but having got the phrase we give a confused meaning to it, we fill up the shell which our abstraction has left, by reintroducing the qualification which we assumed ourselves to have got rid of. We present the mere sensations to ourselves as determined by relation in a way that would be impossible in the absence of that connecting action which we assume to be absent in designating them mere sensations. The minimum of qualification which we mentally ascribe to the sensation in thus speaking of it, is generally such as implies sequence and degree. A feeling not characterised either by its connexion with previous feeling or by its own intensity we must admit to be nothing at all, but at first sight we take it for granted that the character thus given to a feeling would belong to it just the same, though there were no such thing as thought in the world. It certainly does not depend on ourselves--on any power which we can suppose it rests with our will to exert or withhold--whether sensations shall occur to us in this or that order of succession, with this or that degree of intensity. But the question is whether the relation of time between one sensation and another, or that relation between a sensation and other possible modes of itself which is implied in its having a degree, could exist if there were not a subject for which the several sensations, or modes of the same sensation, were equally present and equally distinguished from itself. If it is granted that these relations, which constitute the minimum determination of sensible fact, only exist through the action of a subject, it follows that thought is the necessary condition of the existence of sensible facts, and that mere sensation, in the sense supposed, is not a possible constituent in the realm of facts. (§ 46 ¶ 1)