To Henry Walter Bates 22 November 
Down Bromley Kent
My dear Sir
I thank you sincerely for writing to me & for your very interesting letter. Your name has for very long been familiar to me, & I have heard of your zealous exertions in the cause of Natural History.1 But I did not know that you had worked with high philosophical questions before your mind.2 I have an old belief that a good observer really means a good theorist & I fully expect to find your observations most valuable. I am very sorry to hear that your health is shattered; but I trust under a healthy climate it may be restored. I can sympathise with you fully on this score, for I have had bad health for many years & fear I shall ever remain a confirmed invalid.—
I am delighted to hear that you, with all your large practical knowledge of Nat. History, anticipated me in many respects & concur with me.— As you say I have been thoroughily well attacked & reviled, (especially by entomologists, Westwood, Wollaston & A. Murray have all reviewed & sneered at me to their hearts’ content)3 but I care nothing about their attacks; several really good judges go a long way with me, & I observe that all those who go some little way tend to go somewhat further. What a fine philosophical mind your friend, Mr Wallace has, & he has acted in relation to me, like a true man with a noble spirit.—4 I see by your letter that you have grappled with several of the most difficult problems, as it seems to me, in natural History—such as the distinctions between the different kinds of varieties, representative species &c.5
Perhaps I shall find some facts in your paper on intermediate varieties in intermediate regions,—on which subject I have found remarkably little information.— I cannot tell you how glad I am to hear that you have attended to the curious point of Equatorial refrigeration.6 I quite agree that it must have been small; yet the more I go into that question the more convinced I feel that there was during the Glacial period some migration from N. to S.— The sketch in the Origin gives a very meagre account of my fuller M.S. Essay on this subject.—7
I shall be particularly obliged for a copy of your paper when published; & if any suggestions occur to me (not that you require any) or questions I will write & ask.—
Pray believe me, with respect & good wishes | My dear Sir | Yours sincerely | C. Darwin
I have at once to prepare a new Edit of the Origin, & I will do myself the pleasure of sending you a copy; but it will be only very slightly altered.—
Cases of neuter ants, divided into castes, with intermediate gradations. (which I imagine are rare) interest me much.8 V. Origin on the Driver Ants p.—241.— (please look at the passage)
Thanks for interesting letter which confirms belief that a good observer is a good theorist.
He is glad to hear that HWB, with his wide knowledge of natural history, has anticipated CD in many respects and agrees with the Origin.
Has been thoroughly attacked, especially by entomologists – J. O. Westwood, T. V. Wollaston, and Andrew Murray.
Glad HWB is writing on "equatorial refrigeration"; CD expresses his belief in north to south migration during glacial period.
Please cite as
Darwin Correspondence Project, “Letter no. 2993,” accessed on 24 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-2993