So far we have been following the lead of Kant in enquiring what is necessary to constitute, what is implied in there being, a world of experience--an objective world, if by that is meant a world of ascertainable laws, as distinguished from a world of unknowable things-in-themselves. We have followed him also, as we believe every one must who has once faced the question, in maintaining that a single active self-conscious principle, by whatever name it be called, is necessary to constitute such a world, as the condition under which alone phenomena, i.e. appearances to consciousness, can be related to each other in a single universe. This is the irrefragable truth involved in the proposition that the understanding makes nature. But so soon as we have been brought to the acceptance of that proposition, Kant's leading fails us. We might be forward, from the work thus assigned to understanding in the constitution of nature, to infer something as to the spirituality of the real world. But from any such inference Kantwould at once withhold us. He would not only remind us that the work assigned to understanding is a work merely among and upon phenomena; that the nature which it constitutes is merely a unity in the relations of phenomena; and that any conclusion we arrive at in regard to nature in this sense has no application to things in themselves. He insists, further, on a distinction between the form and matter of nature itself, and, having assigned to its form an origin in understanding, ascribes the matter to an unknown but alien source, in a way which seems to cancel the significance of his own declarations in regard to the intellectual principle necessary to constitute its form. We do not essentially misrepresent him in saying that by the form of nature or, as he sometimes phrases it natura formaliter spectata, he means the relations by which phenomena are connected in the one world of experience; by its matter, or natura materialiter spectata, the mere phenomena or sensations undetermined by those relations. Natura formaliter spectata is the work of the understanding; but natura materialiter spectata is the work of unknown things-in-themselves, acting in unknown ways upon us. (§ 38 ¶ 1)