5 Westbourne Grove Terrace, W. May 10, 1864.

My dear Darwin,—­I was very much gratified to hear by your letter of a month back that you were a little better, and I have since heard occasionally through Huxley and Lubbock that you are not worse.  I sincerely hope the summer weather and repose may do you real good.

The Borneo Cave exploration is to go on at present without a subscription.  The new British consul who is going out to Sarawak this month will undertake to explore some of the caves nearest the town, and if anything of interest is obtained a good large sum can no doubt be raised for a thorough exploration of the whole country.  Sir J. Brooke will give every assistance, and will supply men for the preliminary work.

I send you now my little contribution to the theory of the origin of man.  I hope you will be able to agree with me.  If you are able, I shall be glad to have your criticisms.

I was led to the subject by the necessity of explaining the vast mental and cranial differences between man and the apes combined with such small structural differences in other parts of the body, and also by an endeavour to account for the diversity of human races combined with man’s almost perfect stability of form during all historical epochs.

It has given me a settled opinion on these subjects, if nobody can show a fallacy in the argument.

The Anthropologicals did not seem to appreciate it much, but we had a long discussion which appears almost verbatim in the Anthropological Review.[39]

As the Linnean Transactions will not be out till the end of the year I sent a pretty full abstract of the more interesting parts of my Papilionidae paper[40] to the Reader, which, as you say, is a splendid paper.

Trusting Mrs. Darwin and all your family are well, and that you are improving, believe me yours most sincerely,

ALFRED R. WALLACE.

* * * * *

Down, Bromley, Kent.  May 28, 1864.

Dear Wallace,—­I am so much better that I have just finished a paper for the Linnean Society; but as I am not yet at all strong I felt much disinclination to write, and therefore you must forgive me for not having sooner thanked you for your paper on Man received on the 11th.  But first let me say that I have hardly ever in my life been more struck by any paper than that on variation, etc. etc., in the Reader.  I feel sure that such papers will do more for the spreading of our views on the modification of species than any separate treatises on the single subject itself.  It is really admirable; but you ought not in the Man paper to speak of the theory as mine; it is just as much yours as mine.  One correspondent has already noticed to me your “high-minded” conduct on this head.