consistent with an intellectual—­and which the most analogous cases we can think of in the organic world do not favor; for there is a material connection between the grub, the pupa, and the butterfly, between the tadpole and the frog, or, still better, between those distinct animals which succeed each other in alternate and very dissimilar generations.  So that mere analogy might rather suggest a natural connection than the contrary; and the contrary cannot be demonstrated until the possibilities of Nature under the Deity are fathomed.

But, the intellectual connection being undoubted, Mr. Agassiz properly refers the whole to “the agency of Intellect as its first cause.”  In doing so, however, he is not supposed to be offering a scientific explanation of the phenomena.  Evidently he is considering only the ultimate why, not the proximate why or how.

Now the latter is just what Mr. Darwin is considering.  He conceives of a physical connection between allied species; but we suppose he does not deny their intellectual connection, as related to a supreme intelligence.  Certainly we see no reason why he should, and many reasons why he should not, Indeed, as we contemplate the actual direction of investigation and speculation in the physical and natural sciences, we dimly apprehend a probable synthesis of these divergent theories, and in it the ground for a strong stand against mere naturalism.  Even if the doctrine of the origin of species through natural selection should prevail in our day, we shall not despair; being confident that the genius of an Agassiz will be found equal to the work of constructing, upon the mental and material foundations combined, a theory of Nature as theistic and as scientific as that which he has so eloquently expounded.

To conceive the possibility of “the descent of species from species by insensibly fine gradations” during a long course of time, and to demonstrate its compatibility with a strictly theistic view of the universe, is one thing; to substantiate the theory itself or show its likelihood is quite another thing.  This brings us to consider what Darwin’s theory actually is, and how he supports it.

That the existing kinds of animals and plants, or many of them, may be derived from other and earlier kinds, in the lapse of time, is by no means a novel proposition.  Not to speak of ancient speculations of the sort, it is the well-known Lamarckian theory.  The first difficulty which such theories meet with is that in the present age, with all its own and its inherited prejudgments, the whole burden of proof is naturally, and indeed properly, laid upon the shoulders of the propounders; and thus far the burden has been more than they could bear.  From the very nature of the case, substantive proof of specific creation is not attainable; but that of derivation or transmutation of species may be.  He who affirms the latter view is bound to do one or both of two things:  1.  Either to assign real and adequate causes,