I thank you most sincerely for your letter, which is very interesting to me. I wish I had known of these views of Hippocrates before I had published, for they seem almost identical with mine--merely a change of terms--and an application of them to classes of facts necessarily unknown to the old philosopher. The whole case is a good illustration of how rarely anything is new. Hippocrates has taken the wind out of my sails, but I care very little about being forestalled. I advance the views merely as a provisional hypothesis, but with the secret expectation that sooner or later some such view will have to be admitted. ... I do not expect the reviewers will be so learned as you: otherwise, no doubt, I shall be accused of wilfully stealing Pangenesis from Hippocrates,--for this is the spirit some reviewers delight to show. CHARLES DARWIN TO VICTOR CARUS. Down, March 21 [1868]. ... I am very much obliged to you for sending me so frankly your opinion on Pangenesis, and I am sorry it is unfavourable, but I cannot quite understand your remark on pangenesis, selection, and the struggle for life not being more methodical. I am not at all surprised at your unfavourable verdict; I know many, probably most, will come to the same conclusion. One English Review says it is much too complicated... Some of my friends are enthusiastic on the hypothesis... Sir C. Lyell says to every one, "you may not believe in 'Pangenesis,' but if you once understand it, you will never get it out of your mind." And with this criticism I am perfectly content. All cases of inheritance and reversion and development now appear to me under a new light... [An extract from a letter to Fritz Muller, though of later date (June), may be given here:-- "Your letter of April 22 has much interested me. I am delighted that you approve of my book, for I value your opinion more than that of almost any one. I have yet hopes that you will think well of Pangenesis. I feel sure that our minds are somewhat alike, and I find it a great relief to have some definite, though hypothetical view, when I reflect on the wonderful transformations of animals,--the re-growth of parts,--and especially the direct action of pollen on the mother-form, etc. It often appears to me almost certain that the characters of the parents are "photographed" on the child, only by means of material atoms derived from each cell in both parents, and developed in the child."] CHARLES DARWIN TO ASA GRAY. Down, May 8 [1868]. My dear Gray,