1. That it is a mere hypothesis or conjecture, designed, not to establish the _historical fact_, but to explain merely the _dynamical possibility_ of the production of the planetary bodies by the operation of known natural laws, must be admitted, I think, even by its most enthusiastic admirers. It might have seemed, indeed, to have something like a basis of fact to rest upon, had the conception of the elder Herschell been verified, when he announced the existence of a nebulous fluid, capable of being distinguished, by certain well-defined marks, from unresolved clusters of stars; but even then it presupposed so many postulates, which could in no way be established by experimental or historical evidence, that it could scarcely be regarded in any other light than as an ingenious speculation or a splendid conjecture. For, let it be considered, first of all, that the theory proceeds on the assumption of the existence and wide diffusion of a nebulous fluid of whose reality there is no actual proof; secondly, that it necessarily requires, also, the supposed existence of certain favorable conditions; and, thirdly, the operation of certain invariable laws; and it will be manifest at once that it is purely hypothetical throughout, and that it includes a variety of topics which never have been, and never can be made the subjects of experimental verification. For it postulates, in the words of an acute writer, "the establishment of nuclei in the body of the elemental mass, as well as the action of heat on its substance, and then seeks to explain the concentration of the nebulous particles into these nuclei by the force of gravitation, the rotation of the bodies so produced by the confluence of the nebulous fluid, the separation of a portion of the outer surface of these revolving masses in the form of rings, the disruption of these rings, and the subsequent recomposition of their fragments into separate spheres, answering to the planets and satellites of our system."[32] But even were the existence of a nebulous fluid admitted, we have no access to know what was its internal structure; we cannot determine whether it was uniform and homogeneous throughout, or whether it contained nuclei which might become centres of aggregation; we have no means of estimating the intensity of the heat which belonged to it, or of calculating the process by which it was dispersed, so as to occasion the condensation of successive portions of the mass. No eye ever saw the separation of any part of it in the form of a ring, or the disruption of that ring, or the subsequent recomposition of its fragments into a solid sphere. And even had all this been matter, not of mere conjecture, but of actual observation, it would still have left much to be explained which can only be accounted for by ascribing it to a designing Intelligent Cause.