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the conditions on which it depends； I say that we have no right to
affirm that those conditions will not be better understood by and by；
and we have no ground for supposing that we may not be able to
experiment so as to obtain that crucial result which I mentioned just
now。 So that though Mr。 Darwin's hypothesis does not completely
extricate us from this difficulty at present； we have not the least
right to say it will not do so。
There is a wide gulf between the thing you cannot explain and the thing
that upsets you altogether。 There is hardly any hypothesis in this
world which has not some fact in connection with it which has not been
explained； but that is a very different affair to a fact that entirely
opposes your hypothesis； in this case all you can say is； that your
hypothesis is in the same position as a good many others。
Now； as to the third test； that there are no other causes competent to
explain the phenomena； I explained to you that one should be able to
say of an hypothesis； that no other known causes than those supposed by
it are competent to give rise to the phenomena。 Here； I think； Mr。
Darwin's view is pretty strong。 I really believe that the alternative
is either Darwinism or nothing； for I do not know of any rational
conception or theory of the organic universe which has any scientific
position at all beside Mr。 Darwin's。 I do not know of any proposition
that has been put before us with the intention of explaining the
phenomena of organic nature； which has in its favour a thousandth part
of the evidence which may be adduced in favour of Mr。 Darwin's views。
Whatever may be the objections to his views； certainly all others are
absolutely out of court。
Take the Lamarckian hypothesis； for example。 Lamarck was a great
naturalist； and to a certain extent went the right way to work； he
argued from what was undoubtedly a true cause of some of the phenomena
of organic nature。 He said it is a matter of experience that an animal
may be modified more or less in consequence of its desires and
consequent actions。 Thus； if a man exercise himself as a blacksmith；
his arms will become strong and muscular； such organic modification is
a result of this particular action and exercise。 Lamarck thought that
by a very simple supposition based on this truth he could explain the
origin of the various animal species： he said； for example； that the
short…legged birds which live on fish had been converted into the
long…legged waders by desiring to get the fish without wetting their
bodies； and so stretching their legs more and more through successive
generations。 If Lamarck could have shown experimentally； that even
races of animals could be produced in this way； there might have been
some ground for his speculations。 But he could show nothing of the
kind； and his hypothesis has pretty well dropped into oblivion； as it
deserved to do。 I said in an earlier lecture that there are hypotheses
and hypotheses； and when people tell you that Mr。 Darwin's
strongly…based hypothesis is nothing but a mere modification of
Lamarck's； you will know what to think of their capacity for forming a
judgment on this subject。
But you must recollect that when I say I think it is either Mr。 Darwin's
hypothesis or nothing； that either we must take his view； or look upon
the whole of organic nature as an enigma； the meaning of which is
wholly hidden from us； you must understand that I mean that I accept it
provisionally； in exactly the same way as I accept any other hypothesis。
Men of science do not pledge themselves to creeds； they are bound by
articles of no sort； there is not a single belief that it is not a
bounden duty with them to hold with a light hand and to part with it
cheerfully； the moment it is really proved to be contrary to any fact；
great or small。 And if； in course of time I see good reasons for such
a proceeding； I shall have no hesitation in coming before you； and
pointing out any change in my opinion without finding the slightest
occasion to blush for so doing。 So I say that we accept this view as
we accept any other； so long as it will help us； and we feel bound to
retain it only so long as it will serve our great purposethe
improvement of Man's estate and the widening of his knowledge。 The
moment this； or any other conception； ceases to be useful for these
purposes； away with it to the four winds； we care not what becomes of
it！
But to say truth； although it has been my business to attend closely to
the controversies roused by the publication of Mr。 Darwin's book； I
think that not one of the enormous mass of objections and obstacles
which have been raised is of any very great value； except that
sterility case which I brought before you just now。 All the rest are
misunderstandings of some sort； arising either from prejudice； or want
of knowledge； or still more from want of patience and care in reading
the work。
For you must recollect that it is not a book to be read with as much
ease as its pleasant style may lead you to imagine。 You spin through
it as if it were a novel the first time you read it； and think you know
all about it； the second time you read it you think you know rather
less about it； and the third time； you are amazed to find how little
you have really apprehended its vast scope and objects。 I can
positively say that I never take it up without finding in it some new
view； or light； or suggestion that I have not noticed before。 That is
the best characteristic of a thorough and profound book； and I believe
this feature of the 'Origin of Species' explains why so many persons
have ventured to pass judgment and criticisms upon it which are by no
means worth the paper they are written on。
Before concluding these lectures there is one point to which I must
advert；though； as Mr。 Darwin has said nothing about man in his book；
it concerns myself rather than him；for I have strongly maintained on
sundry occasions that if Mr。 Darwin's views are sound； they apply as
much to man as to the lower mammals； seeing that it is perfectly
demonstrable that the structural differences which separate man from
the apes are not greater than those which separate some apes from
others。 There cannot be the slightest doubt in the world that the
argument which applies to the improvement of the horse from an earlier
stock； or of ape from ape； applies to the improvement of man from some
simpler and lower stock than man。 There is not a single
facultyfunctional or structural； moral； intellectual； or
instinctive；there is no faculty whatever that is not capable of
improvement； there is no faculty whatsoever which does not depend upon
structure； and as structure tends to vary； it is capable of being
improved。
Well； I have taken a good deal of pains at various times to prove this；
and I have endeavoured to meet the objections of those who maintain；
that the structural differences between man and the lower animals are
of so vast a character and enormous extent； that even if Mr。 Darwin's
views are correct； you cannot imagine this particular modification to
take place。 It is； in fact； easy matter to prove that； so far as
structure is concerned； man differs to no greater extent from the
animals which are immediately below him than these do from other members
of the same order。 Upon the other hand； there is no one who estimates
more highly than I do the dignity of human nature； and the width of the
gulf in intellectual and moral matters； which lies between man and the
whole of the lower creation。
But I find this very argument brought forward vehemently by some。 〃You
say that man has proceeded from a modification of some lower animal；
and you take pains to prove that the structural differences which are
said to exist in his brain do not exist at all； and you teach that all
functions； intellectual； moral； and others； are the expression or the
result； in the long run； of structures； and of the molecular forces
which they exert。〃 It is quite true that I do so。
〃Well； but；〃 I am told at once； somewhat triumphantly； 〃you say in the
same breath that there is a great moral and intellectual chasm between
man and the lower animals。 How is this possible when you declare that
moral and intellectual characteristics depend on structure； and yet
tell us that there is no such gulf between the structure of man and that
of the lower animals？〃
I think that objection is based upon a misconception of the real
relations which exist between structure and function； between mechanism
and work。 Function is the expression of molecular forces and
arrangements no doubt； but； does it follow from this； that variation in
function so depends upon variation in structure that the former is
always exactly proportioned to the latter？ If there is no such
relation； if the variation in function which follows on a variation in
structure； may be enormously greater than the variation of the
structure； then； you see； the objection falls to the ground。
Take a couple of watchesmade by the same maker； and as completely
alike as possible； set them upon the table； and the function of
eachwhich is its rate of goingwill be performed in the sam