My dear Darwin

I have read your interesting book with all carefulness as you enjoined,—have gleaned a great deal from it, & consider it one of the most valuable contributions to Nat. Hist Literature of the present day.² Perhaps you may like to know what I think of your particular theory, tho‘ you will doubtless have many opinions offered far more deserving to be weighed than mine. As you are aware, I am no stickler for the multitude of so-called species created by so many naturalists of late years, & I always thought the time was not distant—when, after the brain-splitting process had been carried to it’s utmost length—some at least could see the necessity of retracing their steps, & again uniting a large number of the forms they had so carefully separated.³

But I frankly confess I did not look for any such large assemblages of species to be brought together in this way, as the descendants from one & the same stock, similar to what you have attempted in your volume. By this you will see that I embrace yr theory in part, but hardly to the full extent to which you carry it.⁴ Still I allow you have made out a very strong case, and I will not pretend to say what future researches in the same direction may not ultimately establish.

I can quite fall in with the view that those fossil animals which so closely resemble their living representatives at the present day, are in fact the progenitors of these last;—such indeed has been my opinion for many years, tho’ a contrary one, I know had been adopted by many of our first Geologists & Naturalists. I can also well believe that whole families have had a common parentage at some remote period of the past,—& that the same may have been the case, reasoning analogically (tho’ this is not always safe in Nat. Hist. speculations),—with groups of even higher denomination. But I cannot think that all the difficulties which stand in the way of so extensive a generalization have been entirely got over—

It seems to me that if “all organic beings that have ever lived on the earth, had descended from some one primordial form”, as you seem to think possible,—we should find (either among the fossil or living species) the same connecting links, & “fine gradations” between the highest groups, that we do find among the lower, & which renders classification & definition so difficult.⁵ Thus birds as a class may be shown to be all more & less closely connected, with only here & there a saltus which we cannot hedge over: the same perhaps of all vertebrate animals—if we had all the lost & unknown living forms at hand to fill up the gaps;—but when we come to another quite distinct type of organization—the annulose, for instance, how little of intermediate between this & the vertebrate, or between either of these & the molluscous, &c. Still more what an hiatus between vegetables & animals, tho’ just at their respective origins, or where the vital powers seems least active, they are scarcely separable by any distinguishing characters. But why should this never be the case afterwards—& not merely at the beginning of things—if they originally sprung from the same primordial germ?

One great difficulty to my mind in the way of your theory is the fact of the existence of Man. I was beginning to think you had entirely passed over this question, till almost in the last page I find you saying that ‘light will be thrown on the origin of man & his history’. By this I suppose is meant that he is to be considered a modified & no doubt greatly improved orang! I doubt if this will find acceptance with the generality of readers— I am not one of those in the habit of mixing up questions of science & scripture,⁶ but I can hardly see what sense or meaning is to be attached to Gen: 2.7. & yet more to vv. 21. 22, of the same chapter, giving an account of the creation of wo man,—if the human species at least has not been created independently of other animals, but merely come into the world by ordinary descent from previously existing races—whatever those races may be supposed to have been. Neither can I easily bring myself to the idea that man’s reasoning faculties & above all his moral sense, c^d. ever have been obtained from irrational progenitors, by mere natural selection—acting however gradually & for whatever length of time that may be required. This seems to be doing away altogether with the Divine Image which forms the insurmountable distinction between man & brutes.