The scheme of creation, moreover, implied in the development theory, proceeds, as it appears to us, upon an inconsistency of assumption that is completely at variance with its own leading cardinal principle, namely, a continuous progression from the less to the more perfect forms of organic existence. If this be true with the _particulars_, why not also in the _generals_ of all that is endowed with the mystery of life? Every great type or class of being, whose remains are detected in the most ancient rocks of the earth, has still its representatives in living nature. The two ends of the chain, the infusorial and mammalian families, are still produced distinct, and each perfect after its kind. The course of creation is thus always, through indefinite time, returning upon itself like the fallacy in dialectics of reasoning in a circle, instead of advancing from the successively higher standards of the perfected models to still more varied and perfect degrees of excellence. The circumstances and conditions, too, of the planet are different from what they were in the palæozoic times, and yet the tribes developed then are all developed still; different in the species and genera, but of the same forms and families; not larger, but more frequently less, in size, and not of better or more complex workmanship. The principle is, therefore, inconsistent with itself, while it leaves unexplained its own assumption of progression in _one_ particular direction only, instead, as it ought to be, in all the primitive types of organic existence. The theory is imperfect beside, in attempting no explanation of the inorganic structures of creation; for the original molecules of matter which assimilated, aggregated, and produced the primary rocks of granite, gneiss, schist, limestone, should have had their law in this direction as well as in the other, of progressive perfection. But these rocks, in no such sense as this, have been repeated or reproduced: matter, essentially the same, according to the theory of the “Vestiges,” whether organic or inorganic, has here retrograded rather than progressed; and if we would contemplate its most elaborate and beautiful forms, either igneous or sedimentary, we must go, not to the secondary and tertiary formations for our specimens, but to the crystalline groups of the primary epoch.