§ 15.

So far we have only reached the conclusion that a conception, to which understanding is related as faculty to function, is the condition of our ability to distinguish a real from the unreal, matter of fact from illusion. It will be said perhaps that so much pains need not have been spent on establishing a proposition which in effect merely tells us that without a conception of an order of nature we could not conceive an order of nature. Is not this, it may be asked, either an identical proposition or untrue—an identical proposition, if understood strictly as thus put; untrue, if taken to mean that the conception of an order of nature does not admit of being generated out of materials other than itself? Now it is just the difficulties in the way of explaining the origin of the conception in question out of anything else than judgments which presuppose it, that we wish to exhibit. They are the difficulties which beset any theory that would treat the knowledge of nature as itself the result of natural processes. It is through experience that every such theory must suppose the resulting knowledge to be produced. But experience, as most students of philosophy must now be aware, is a term used in very different senses. In this case an experience which is to yield the required result must not be merely an experience in the sense in which, for instance, a plant might be said to experience a succession of atmospheric or chemical changes, or in which we ourselves pass through a definite physical experience during sleep or in respect of the numberless events which affect us but of which we are not aware. Such an experience may no doubt gradually alter to any extent the mode in which the physical organism reacts upon stimulus. It may be the condition of its becoming organic to intellectual processes, but between it and experience of the kind which is to yield a knowledge of nature there is a chasm which no one, except by confusion of speech, has attempted to fill. Or to speak more precisely, between the two senses of experience there is all the difference that exists between change and consciousness of change. (§ 15 ¶ 1)