To J. D. Hooker 11 May 
Down Bromley Kent
My dear Hooker
Thank you for telling me about obscurity of style. But on my life no nigger with lash over him could have worked harder at clearness than I have. But the very difficulty to me, by itself leads to probability that I fail. Yet one lady who has read all my M.S. has found only 2 or 3 obscure sentence.1 But Mrs. Hooker having so found it, makes me tremble.—2 I will do my best in proofs. You are a good man to take trouble to write about it—
With respect to our mutual muddle, I never for a moment thought we could not make our ideas clear to each other by talk or if either of us had time to write in extenso.
I imagine from some expressions (but if you asked me what, I could not answer) that you look at variability as some necessary contingency with organisms, & further that there is some necessary tendency in the variability to go on diverging in character or degree.3 If you do, I do not agree. “Reversion” again, (a form of inheritance) I look at as 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 signification 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 & good Lord how I do long to have done with it:—
Since the above was written I have received & been much interested by A. Gray. I am delighted at his note about my & Wallace’s paper:4 He will go round, for it is futile to give up very many species, & stop at an arbitrary line at others. It is what my grandfather called Unitarianism, “a feather-bed to catch a falling Christian”.—5
The geology at p. 447 seems to be inextricable confusion.6
Some time ago A. Gray wrote to me for my notions on recent migration during late periods, & I gave him the passage before Glacial period by the almost continuous circumpolar land.— I presume he alludes to this, not correctly, by putting me before E. Forbes Hooker & De Candolle.—7
But he has changed my doctrine, apparently after consulting Dana.—8 I knew there was some slight evidence from range of the shell Gnathodon in U. States of warmer climate since Glacial epoch; but I do not believe there is any such evidence for Europe.— I once consulted Lyell on this point & he seemed to know little & be very doubtful about this warmer period since Glacial. I doubt whether Megatherium & Co. have really been found together with the northern Elephant; nor do I at all admit that Megatherium, Mylodon & Co are by themselves proof of warmer climate. The argument from the woolly Elephant & woolly Rhinoceros I look at as false.9
If my letter did start these speculations, I am sorry I ever wrote it, for in my opinion they botch the subject.—
Yours affect | C. Darwin
I return the Paper by this Post
JDH finds style of CD’s MS obscure.
CD wary of JDH’s starting point on variability: it is not inherent, it does not lead necessarily to divergence, and it must be distinguished from inheritance.
Asa Gray has misread CD’s views on pre-glacial migrations and botched the subject.