Do not act and say, like Macleay versus Fleming, "I write with aqua fortis to bite into brass."
Ever yours, C. DARWIN.
CHARLES DARWIN TO C. LYELL. Ilkley, Yorkshire, October 20th [1859].
My dear Lyell,
I have been reading over all your letters consecutively, and I do not feel that I have thanked you half enough for the extreme pleasure which they have given me, and for their utility. I see in them evidence of fluctuation in the degree of credence you give to the theory; nor am I at all surprised at this, for many and many fluctuations I have undergone.
There is one point in your letter which I did not notice, about the animals (and many plants) naturalised in Australia, which you think could not endure without man's aid. I cannot see how man does aid the feral cattle. But, letting that pass, you seem to think, that because they suffer prodigious destruction during droughts, that they would all be destroyed. In the "gran secos" of La Plata, the indigenous animals, such as the American deer, die by thousands, and suffer apparently as much as the cattle. In parts of India, after a drought, it takes ten or more years before the indigenous mammals get up to their full number again. Your argument would, I think, apply to the aborigines as well as to the feral.
An animal or plant which becomes feral in one small territory might be destroyed by climate, but I can hardly believe so, when once feral over several large territories. Again, I feel inclined to swear at climate: do not think me impudent for attacking you about climate. You say you doubt whether man could have existed under the Eocene climate, but man can now withstand the climate of Esquimaux-land and West Equatorial Africa; and surely you do not think the Eocene climate differed from the present throughout all Europe, as much as the Arctic regions differ from Equatorial Africa?
With respect to organisms being created on the American type in America, it might, I think, be said that they were so created to prevent them being too well created, so as to beat the aborigines; but this seems to me, somehow, a monstrous doctrine.
I have reflected a good deal on what you say on the necessity of continued intervention of creative power. I cannot see this necessity; and its admission, I think, would make the theory of Natural Selection valueless. Grant a simple Archetypal creature, like the Mud-fish or Lepidosiren, with the five senses and some vestige of mind, and I believe natural selection will account for the production of every vertebrate animal.
Farewell; forgive me for indulging in this prose, and believe me, with cordial thanks,
Your ever attached disciple, C. DARWIN.
P.S.--When, and if, you reread, I supplicate you to write on the margin the word "expand," when too condensed, or "not clear." or "?." Such marks would cost you little trouble, and I could copy them and reflect on them, and their value would be infinite to me.
My larger book will have to be wholly re-written, and not merely the present volume expanded; so that I want to waste as little time over this volume as possible, if another edition be called for; but I fear the subject will be too perplexing, as I have treated it, for general public.
CHARLES DARWIN TO J.D. HOOKER. Ilkley, Yorkshire, Sunday [October 23rd, 1859].
My dear Hooker,
I congratulate you on your 'Introduction' ("Australian Flora".) being in fact finished. I am sure from what I read of it (and deeply I shall be interested in reading it straight through), that it must have cost you a prodigious amount of labour and thought. I shall like very much to see the sheet, which you wish me to look at. Now I am so completely a gentleman, that I have sometimes a little difficulty to pass the day; but it is astonishing how idle a three weeks I have passed. If it is any comfort to you, pray delude yourself by saying that you intend "sticking to humdrum science." But I believe it just as much as if a plant were to say that, "I have been growing all my life, and, by Jove, I will stop growing." You cannot help yourself; you are not clever enough for that.