Dear Sir

I am very much obliged for your kind letter, and I have waited for a week before answering it, in hopes of receiving the “Kleine Schrift” to which you allude; but I fear it is lost, which I am much surprised at, as I have seldom failed to receive any thing sent by the post.¹

As I do not know the title and cannot order a copy; I should be very much obliged if you can spare another.

I am delighted that you, with whose name I am familiar, should approve of my work. I entirely agree with what you say about each species varying according to its own peculiar laws; but at the same time it must, I think, be admitted, that the variations of most species have in the lapse of ages been extremely diversified; for I do not see how it can be otherwise explained that so many forms have acquired analogous structures for the same general object, independently, of descent. I am very glad to hear that you have been arguing against Nägeli’s law of perfectibility which seems to me superfluous.² Others hold similar views, but none of them define what this “perfection” is, which cannot be gradually attained through Natural Selection. I thought M. Wagner’s first pamphlet (for I have not yet had time to read the second) very good and interesting; but I think that he greatly overrates the necessity for emigration and isolation.³ I doubt whether he has reflected on what must occur when his forms colonize a new country, unless they vary during the very first generation; nor does he attach, I think, sufficient weight to the cases of what I have called unconscious selection by man;⁴ in these cases races are modified by the preservation of the best and the destruction of the worst, without any isolation.

I sympathize with you most sincerely, on the state of your eye-sight;⁵ it is indeed the most fearful evil which can happen to any one who like yourself is earnestly attached to the pursuit of natural knowledge.

With the most sincere respect pray believe me | dear Sir | Yours very faithfully | Charles Darwin