I often vow to myself that I will utterly disregard every statement made by any one who has not shown the world he can observe accurately." In a letter to Dr. Dohrn, of Naples, January 4th, 1870, Darwin wrote: "Forgive me for suggesting one caution; as Demosthenes said, 'Action, action, action,' was the soul of eloquence, so is caution almost the soul of science.")
LETTER 778. TO J. BURDON SANDERSON. Down, July 16th, 1875.
Some little time ago Mr. Simon (778/1. Now Sir John Simon) sent me the last Report, and your statements about contagion deeply interested me. By the way, if you see Mr. Simon, and can remember it, will you thank him for me; I was so busy at the time that I did not write. Having been in correspondence with Paget lately on another subject, I mentioned to him an analogy which has struck me much, now that we know that sheep-pox is fungoid; and this analogy pleased him. It is that of fairy rings, which are believed to spread from a centre, and when they intersect the intersecting portion dies out, as the mycelium cannot grow where it has grown during previous years. So, again, I have never seen a ring within a ring; this seems to me a parallel case to a man commonly having the smallpox only once. I imagine that in both cases the mycelium must consume all the matter on which it can subsist.
LETTER 779. TO A. GAPITCHE.
(779/1. The following letter was written to the author (under the pseudonym of Gapitche) of a pamphlet entitled "Quelques mots sur l'Eternite du Corps Humaine" (Nice, 1880). Mr. Gapitche's idea was that man might, by perfect adaptation to his surroundings, indefinitely prolong the duration of life. We owe Mr. Darwin's letter to the kindness of Herr Vetter, editor of the well-known journal "Kosmos.")
Down, February 24th, 1880.
I suppose that no one can prove that death is inevitable, but the evidence in favour of this belief is overwhelmingly strong from the evidence of all other living creatures. I do not believe that it is by any means invariably true that the higher organisms always live longer than the lower ones. Elephants, parrots, ravens, tortoises, and some fish live longer than man. As evolution depends on a long succession of generations, which implies death, it seems to me in the highest degree improbable that man should cease to follow the general law of evolution, and this would follow if he were to be immortal.
This is all that I can say.
LETTER 780. TO J. POPPER.
(780/1. Mr. Popper had written about a proposed flying machine in which birds were to take a part.)
Down, February 15th, 1881.
I am sorry to say that I cannot give you the least aid, as I have never attended to any mechanical subjects. I should doubt whether it would be possible to train birds to fly in a certain direction in a body, though I am aware that they have been taught some tricks. Their mental powers are probably much below those of mammals. It is said, and I suppose truly, that an eagle will carry a lamb. This shows that a bird may have great power for a short distance. I cannot remember your essay with sufficient distinctness to make any remarks on it. When a man is old and works hard, one subject drives another out of his head.
LETTER 781. TO T.H. HUXLEY. Worthing, September 9th, 1881.
(781/1. Mr. Anthony Rich left his house at Worthing as a legacy to Mr. Huxley. See Huxley's "Life and Letters," II., pages 286, 287.)
We have been paying Mr. Rich a little visit, and he has often spoken of you, and I think he enjoyed much your and Mrs. Huxley's visit here. But my object in writing now is to tell you something, which I am very doubtful whether it is worth while for you to hear, because it is uncertain. My brother Erasmus has left me half his fortune, which is very considerable. Therefore, I thought myself bound to tell Mr. Rich of this, stating the large amount, as far as the executors as yet know it roughly. I then added that my wife and self thought that, under these new circumstances, he was most fully justified in altering his will and leaving his property in some other way.