In view of these considerations, therefore, I think it is perfectly clear that if the argument from teleology is to be saved at all, it can only be so by shifting it from the narrow basis of special adaptations, to the broad area of Nature as a whole.  And here I confess that to my mind the argument does acquire a weight which, if long and attentively considered, deserves to be regarded as enormous.  For, although this and that particular adjustment in Nature may be seen to be proximately due to physical causes, and although we are prepared on the grounds of the largest possible analogy to infer that all other such particular cases are likewise due to physical causes, the more ultimate question arises, How is it that all physical causes conspire, by their united action, to the production of a general order of Nature?  It is against all analogy to suppose that such an end as this can be accomplished by such means as those, in the way of mere chance or ’the fortuitous concourse of atoms.’  We are led by the most fundamental dictates of our reason to conclude that there must be some cause for this co-operation of causes.  I know that from Lucretius’ time this has been denied; but it has been denied only on grounds of feeling.  No possible reason can be given for the denial which does not run counter to the law of causation itself.  I am therefore perfectly clear that the only question which, from a purely rational point of view, here stands to be answered is this—­Of what nature are we to suppose the causa causarum to be?

On this point only two hypotheses have ever been advanced, and I think it is impossible to conceive that any third one is open.  Of these two hypotheses the earliest, and of course the most obvious, is that of mental purpose.  The other hypothesis is one which we owe to the far-reaching thought of Mr. Herbert Spencer.  In Chapter VII of his First Principles he argues that all causation arises immediately out of existence as such, or, as he states it, that ’uniformity of law inevitably follows from the persistence of force.’  For ’if in any two cases there is exact likeness not only between those most conspicuous antecedents which we distinguish as the causes, but also between those accompanying antecedents which we call the conditions, we cannot affirm that the effects will differ, without affirming either that some force has come into existence or that some force has ceased to exist.  If the co-operative forces in the one case are equal to those in the other, each to each, in distribution and amount; then it is impossible to conceive the product of their joint action in the one case as unlike that in the other, without conceiving one or more of the forces to have increased or diminished in quantity; and this is conceiving that force is not persistent.’