I am not shaken about the female protected butterflies: I will grant (only for argument) that the life of the male is of _very_ little value; I will grant that the males do not vary; yet why has not the protective beauty of the female been transferred by inheritance to the male? The beauty would be a gain to the male, as far as we can see, as a protection; and I cannot believe that it would be repulsive to the female as she became beautiful. But we shall never convince each other. I sometimes marvel how truth progresses, so difficult is it for one man to convince another unless his mind is vacant. Nevertheless, I myself to a certain extent contradict my own remark; for I believe _far more_ in the importance of protection than I did before reading your articles. I do not think you lay nearly stress enough in your articles on what you admit in your letter, viz. "there seems to be some production of vividness ... of colour in the male independent of protection." This I am making a chief point; and have come to your conclusion so far that I believe that intense colouring in the female sex is often checked by being dangerous. That is an excellent remark of yours about no known case of the male _alone_ assuming protective colours; but in the cases in which protection has been gained by dull colours, I presume that sexual selection would interfere with the male losing his beauty. If the male alone had acquired beauty as a protection, it would be most readily overlooked, as males are so often more beautiful than their females. Moreover, I grant that the loss of the male is somewhat less precious and thus there would be less rigorous selection with the male, so he would be less likely to be made beautiful through Natural Selection for protection. (This does not apply to sexual selection, for the greater the excess of males and the less precious their lives, so much the better for sexual selection.) But it seems to me a good argument, and very good if it could be thoroughly established.--Yours most sincerely, C. DARWIN. I do not know whether you will care to read this scrawl. P.S.--I heard yesterday that my photograph had been sent to your London address--Westbourne Grove. * * * * * _Down, Bromley, Kent, S.E. May 5, 1868._