resent. We did
not yet know enough of matter in its essential constitution nor of the
various forces of nature; and all he could say was that everything
pointed to its having been a development out of matter--a phase of that
continuous process of evolution by which the whole universe had been
brought to its present condition. And so we had to wait and work
contentedly at minor problems. And now, after forty years, though
Spencer and Darwin and Weismann have thrown floods of light on the
phenomena of life, its essential nature and its origin remain as great a
mystery as ever. Whatever light we do possess is from a source which
Spencer and Darwin neglected or ignored."[27]

In his presidential address to the Entomological Society in 1872 Wallace
made some special allusion to Spencer's theory of the origin of
instincts, and on receiving a copy of the address Spencer wrote: "It is
gratifying to me to find that your extended knowledge does not lead you
to scepticism respecting the speculation of mine which you quote, but
rather enables you to cite further facts in justification of it.
Possibly your exposition will lead some of those, in whose lines of
investigation the question lies, to give deliberate attention to it." A
further proof of his confidence was shown by asking Wallace (in 1874) to
look over the proofs of the first six chapters of his "Principles of
Sociology" in order that he might have the benefit of his criticisms
alike as naturalist, anthropologist, and traveller.

This brief reference to the illustrious group of men to whom we owe the
foundations of this new epoch of evolutionary thought--and not the
foundations only, but also the patient building up of the structure upon
which each one continued to perform his allotted task--and the prefatory
notes and the footnotes attached to the letters will serve to elucidate
the historical correspondence between Darwin and Wallace which follows.

PART II (_Continued_)

II.--The Complete Extant Correspondence between Wallace and Darwin

[1857--81]

"I hope it is a satisfaction to you to reflect--and very few
things in my life have been more satisfactory to me--that we have
never felt any jealousy towards each other, though in some senses
rivals. I believe I can say this of myself with truth, and I am
absolutely sure that it is true of you."--DARWIN to Wallace.

"To have thus inspired and retained this friendly feeling,
not