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comparatively easy for us to conceive some such modification of 
those laws as Mr Darwin suggests, — to suppose that any given 
animal should occasionally produce offspring slightly different from 
itself in some one portion of its structure, and that such differences 
should go on accumulating, until finally they end in the most 
divergent forms. But to imagine processes which shall be the most 
easily conceivable goes but a very little way in science ; and, after 
all, the difficulty is but postponed. Mr Darwin himself is obliged 
to have recourse at last to the ordinary forms of language in which 
the idea of creation is expressed, and speaks of a primordial form 
into which “ life was first breathed.” In science we may sometimes 
allow the question to be asked, “ What is most easily conceivable?” 
but only on condition that it be followed hard by the farther question, 
“ How much of this easiness of conception is gained at the expense 
of departure from the evidence of facts and the experience of nature ?” 
In answer to this inquiry, it may well be doubted whether Mr Dar- 
win has proved one single fact capable of sustaining the very first 
step in his ingenious argument. That argument seems to be as 
follows: Man has succeeded by “artificial selection” — that is, by 
careful “breeding” — in establishing certain modifications in the forms 
of domestic animals. Therefore, similar results may be produced to 
an infinitely greater degree by nature. Only, the principle of selec- 
tion will be different. Man chooses those qualities which are most 
useful to him as master. Nature will choose those which are most 
useful to the animal itself. But the qualities which are most useful 
to an animal will be those which enable it to survive when its 
fellows and congeners die. If, therefore, any such qualities arise 
in any particular family or breed, they will be preserved and per- 
petuated. This is a beautiful theory. But when we ask how 
far the facts carry us towards the “origin of new species,” we find 
that there is in reality no perceptible advance. The changes pro- 
ducible by breeding, or by “artificial selection,” are all confined 
within a circle which indicates a restraining law. The changes 
producible by “ natural selection” are, so far as we know and can 
observe, under similar, if not under still narrower limitation. As 
regards the first, Mr Darwin himself supplies us with an illustration 
beyond all others striking, of that law of reversion to type, the 
existence of which he nevertheless disputes. Pigeons are his favourite 
example of extreme modification of form. They have been “ bred” 
