I imagine from some expressions (but if you ask me what, I could not answer) that you look at variability as some necessary contingency with organisms, and further that there is some necessary tendency in the variability to go on diverging in character or degree. IF YOU DO, I do not agree. "Reversion" again (a form of inheritance), I look at as in no way directly connected with Variation, though of course inheritance is of fundamental importance to us, for if a variation be not inherited, it is of no significance to us. It was on such points as these I FANCIED that we perhaps started differently.
I fear that my book will not deserve at all the pleasant things you say about it; and Good Lord, how I do long to have done with it!
Since the above was written, I have received and have been MUCH INTERESTED by A. Gray. I am delighted at his note about my and Wallace's paper. He will go round, for it is futile to give up very many species, and stop at an arbitrary line at others. It is what my grandfather called Unitarianism, "a feather bed to catch a falling Christian."...
CHARLES DARWIN TO J.D. HOOKER. Down, May 18th [1859].
My dear Hooker,
My health has quite failed. I am off to-morrow for a week of Hydropathy. I am very very sorry to say that I cannot look over any proofs (Of Sir J. Hooker's Introduction to the 'Flora of Australia.') in the week, as my object is to drive the subject out of my head. I shall return to-morrow week. If it be worth while, which probably it is not, you could keep back any proofs till my return home.
In haste, ever yours, C. DARWIN.
[Ten days later he wrote to Sir J.D. Hooker: