If theories of derivation could only stop here, content with explaining the diversification and succession of species between the teritiary period and the present time, through natural agencies or secondary causes still in operation, we fancy they would not be generally or violently objected to by the savants of the present day.  But it is hard, if not impossible, to find a stopping-place.  Some of the facts or accepted conclusions already referred to, and several others, of a more general character, which must be taken into the account, impel the theory onward with accumulated force.  Vires (not to say virus) acquirit eundo.  The theory hitches on wonderfully well to Lyell’s uniformitarian theory in geology—­that the thing that has been is the thing that is and shall be—­that the natural operations now going on will account for all geological changes in a quiet and easy way, only give them time enough, so connecting the present and the proximate with the farthest past by almost imperceptible gradations—­a view which finds large and increasing, if not general, acceptance in physical geology, and of which Darwin’s theory is the natural complement.

So the Darwinian theory, once getting a foothold, marches; boldly on, follows the supposed near ancestors of our present species farther and yet farther back into the dim past, and ends with an analogical inference which “makes the whole world kin.”  As we said at the beginning, this upshot discomposes us.  Several features of the theory have an uncanny look.  They may prove to be innocent:  but their first aspect is suspicious, and high authorities pronounce the whole thing to be positively mischievous.  In this dilemma we are going to take advice.  Following the bent of our prejudices, and hoping to fortify these by new and strong arguments, we are going now to read the principal reviews which undertake to demolish the theory—­with what result our readers shall be duly informed.

II

“I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained, namely, that each species has been independently created, is erroneous.  I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species.  Furthermore, I am convinced that Natural Selection has been the main, but not exclusive, means of modification.”

This is the kernel of the new theory, the Darwinian creed, as recited at the close of the introduction to the remarkable book under consideration.  The questions, “What will he do with it?” and “How far will he carry it?” the author answers at the close of the volume: