ection which, like a previous one, touches upon the
intimate relations between Darwin and Wallace, and the points on which
they agreed or differed, it is well, as the differences have been
exaggerated and misunderstood, to bear in mind his own declaration:
"None of my differences from Darwin imply any real divergence as to the
overwhelming importance of the great principle of natural selection,
while in several directions I believe that I have extended and
strengthened it."[8]

With these explanatory notes the reader will now be able to follow the
two groups of letters on Natural Selection, Geographical Distribution,
and the Origin of Life and Consciousness which follow.

PART III (_Continued_)

II.--Correspondence on Biology, Geographical Distribution, etc.

[1864-93]

* * * * *

H. SPENCER TO A.R. WALLACE

_29 Bloomsbury Square, W.C. May 19, 1864._

My dear Sir,--When I thanked you for your little pamphlet[9] the other
day, I had not read it. I have since done so with great interest. Its
leading idea is, I think, undoubtedly true, and of much importance
towards an interpretation of the facts. Though I think that there are
some purely physical modifications that may be shown to result from the
direct influence of civilisation, yet I think it is quite clear, as you
point out, that the small amounts of physical differences that have
arisen between the various human races are due to the way in which
mental modifications have served in place of physical ones.

I hope you will pursue the inquiry. It is one in which I have a
direct interest, since I hope, hereafter, to make use of its
results.--Sincerely yours,

HERBERT SPENCER

* * * * *

SIR C. LYELL TO A.R. WALLACE

_53 Harley Street. May 22, [1864]._

My dear Sir,--I have been reading with great interest your paper on the
Origin of the Races of Man, in which I think the question between the
two opposite parties is put with such admirable clearness and fairness
that that alone is no small assistance towards clearing the way to a
true theory. The manner in which you have given Darwin the whole credit
of the theory of Natural Selection is very handsome, but if anyone else
had done it without allusion to your papers it would have been wrong....
With many thanks for your most admirable paper, believe me, my dear Sir,
ever very truly yours,

CHA. LYELL.

* * *