Let any one endeavor to assign a reason for the sole, exclusive existence either of "matter" or of "spirit," or a distinct, specific ground for the opinion that they are necessarily incompatible with each other, and he will be compelled to own that the theory of "unisubstancisme," however plausible by reason of its apparent simplicity, is really nothing more than a gratuitous assumption. It cannot be admitted with reference even to _nature_ and _man_ without confounding the simplest elements of human knowledge; and with reference to _God_ and the _universe_, it is attended with still more fatal consequences, since it must lead, if consistently followed out, to undisguised Pantheism. Why should it be supposed that there is, or can only be, _one_ substance in Nature? one substance invested with all those properties and powers which exist, in such manifold diversity, in the organic and inorganic kingdoms? The wonder might rather seem to be that any _two_ substances should be capable of accounting for such a variety of phenomena as the universe exhibits. A "dualism" is unavoidable, unless we are to materialize God as well as man; and why may there not be a "dualism" in the case of created _mind_ and _matter_, as there must be, on any supposition except that of Pantheism, in the case of the uncreated mind and the material universe? We see variety and gradation in all the works of God; we see thousands of substances, simple and compound, possessing various properties, even in the inorganic world; we see different forms of life, vegetable and animal, ascending by steps of regular gradation, from the lowest to the highest; we see, in the animal kingdom, various propensities, instincts, and powers, which constitute the characteristics of distinct species; at length we rise to Man, with his rational, responsible, and immortal nature. Why may not Man be the _nexus_ between a world of "matter" and a world of "spirits,"--Man, who is equally connected with the material world by his body, and with the spiritual by his soul,--who is, as it were, "mind incarnate," spirit in flesh? And why may there not be higher spirits still, whether embodied in subtler and more refined vehicles, or existing apart from all material forms, in those other worlds which Astronomy has brought to light? No reason can be assigned for a negative answer to these and similar queries, unless it be that _we cannot conceive of pure spirit without bodily form_; and this may be true, if it be meant merely to affirm that we can find no sensible image for it, nothing by which it can be represented to our sight, or pictured in our imagination, as visible things may be; but it is not true, if it be meant to imply that we have no distinct notion of "mind" or "spirit," for it is as clearly known by its properties, of thought, feeling, volition, and consciousness, as matter itself can be; and who will venture to define, or to depict, or to form any image of _the substance