CHARLES DARWIN TO A.R. WALLACE. Down, January 30 [1871]. My dear Wallace, (In the note referred to, dated January 27, Mr. Wallace wrote:-- "Many thanks for your first volume which I have just finished reading through with the greatest pleasure and interest; and I have also to thank you for the great tenderness with which you have treated me and my heresies." The heresy is the limitation of natural selection as applied to man. My father wrote ('Descent of Man,' i. page 137):--"I cannot therefore understand how it is that Mr. Wallace maintains that 'natural selection could only have endowed the savage with a brain a little superior to that of an ape.'" In the above quoted letter Mr. Wallace wrote:--"Your chapters on 'Man' are of intense interest, but as touching my special heresy not as yet altogether convincing, though of course I fully agree with every word and every argument which goes to prove the evolution or development of man out of a lower form.") Your note has given me very great pleasure, chiefly because I was so anxious not to treat you with the least disrespect, and it is so difficult to speak fairly when differing from any one. If I had offended you, it would have grieved me more than you will readily believe. Secondly, I am greatly pleased to hear that Volume I. interests you; I have got so sick of the whole subject that I felt in utter doubt about the value of any part. I intended, when speaking of females not having been specially modified for protection, to include the prevention of characters acquired by the male being transmitted to the female; but I now see it would have been better to have said "specially acted on," or some such term. Possibly my intention may be clearer in Volume II. Let me say that my conclusions are chiefly founded on the consideration of all animals taken in a body, bearing in mind how common the rules of sexual differences appear to be in all classes. The first copy of the chapter on Lepidoptera agreed pretty closely with you. I then worked on, came back to Lepidoptera, and thought myself compelled to alter it--finished Sexual Selection and for the last time went over Lepidoptera, and again I felt forced to alter it. I hope to God there will be nothing disagreeable to you in Volume II., and that I have spoken fairly of your views; I am fearful on this head, because I have just read (but not with sufficient care) Mivart's book ('The Genesis of Species,' by St. G. Mivart, 1871.), and I feel ABSOLUTELY CERTAIN that he meant to be fair (but he was stimulated by theological fervour); yet I do not think he has been quite fair... The part which, I think, will have most influence is where he gives the whole series of cases like that of the whalebone, in which we cannot explain the gradational steps; but such cases have no weight on my mind--if a few fish were extinct, who on earth would have ventured even to conjecture that lungs had originated in a swi-bladder? In such a case as the Thylacine, I think he