"The popular or habitual conception of mankind in general is that there are two distinct worlds mixed up in the phenomenal Cosmos--a world of Mind, consisting of multitudes of individual minds, and a world of Matter, consisting of all the extended immensity and variety of material objects. Neither of these worlds is thought of as begotten of the other, but each of them as existing independently in its own proper nature and within its own definite bounds, though they traffic with each other at present. Sweep away all existing minds, and the deserted Earth would continue to spin round all the same, still whirling its rocks, trees, clouds, and all the rest of its material pomp and garniture, alternately in the sunshine and in the depths of the starry stillness. Though no eye should behold, and no ear should hear, there would be evenings of silver moonlight on the ocean-marge, and the waves would roar as they broke and retired. On the other hand, suppose the entire fabric of the material Universe abolished and dissolved, and the dishoused population of spirits would still somehow survive in the imaginable vacancy. If this second notion is not so easy or common as the first, it still virtually belongs to the popular conception of the contents or constitution of the Cosmos. The conception is that of a Natural Dualism, or of the contact in every act of perception of two distinct spheres, one an internal perceiving mind, and the other an external world composed of the actual and identical objects which this mind perceives.