At this point we may probably anticipate a rejoinder to some such effect as the following. It appears to be impossible to take the matter of experience to be the effect of things-in-themselves, since these things, if they are to be things-in-themselves, cannot be supposed to exist in a relation which only holds for the world of experience, as determined by an intelligent subject. But it must be equally impossible to consider it a product of the intelligent subject, to which, when we have allowed every function that can be claimed for it in the way of uniting in a related system the manifold material of sensation, we must still deny the function of generating that material. Yet we cannot ignore sensation. We cannot reduce the world of experience to a web of relations in which nothing is related, as it would be if everything were erased from it which we cannot refer to the action of a combining intelligence. After all our protests against Dualism, then, are we not at last left with an unaccountable residuum--an essential element of the real world of experience, which we cannot trace to what we regard as the organising principle of that world, but which is as necessary to make the world what it is as that principle itself? What do we gain by excluding other ways of accounting for it, if it is finally irreducible to the only agency by which we can explain the order of the world? Does it not remain a thing-in-itself, alien and opposite to anything that we can explain as the construction of intelligence, just as much as if it were admitted to be the product of an unknowable power? (§ 42 ¶ 1)