Of course the teleologist will here answer—­’The fact of such a gradual building up is no argument against design:  whether the structure appeared on a sudden or was the result of a slow elaboration, the marks of design in either case occur in the structure as it stands.’  All of which is very true; but I am not maintaining that the fact of a gradual development in itself does affect the argument from design.  I am maintaining that it only does so because it reveals the possibility (excluded by the hypothesis of sudden or special creation) of the structure having been proximately due to the operation of physical causes.  Thus, for the value of argument, let us assume that natural selection has been satisfactorily established as a cause adequate to account for all these effects.  Given the facts of heredity, variation, struggle for existence, and the consequent survival of the fittest, what follows?  Why that each step in the prolonged and gradual development of the eye was brought about by the elimination of all the less adapted structures in any given generation, i.e. the selection of all the better adapted to perpetuate the improvement by heredity.  Will the teleologist maintain that this selective process is itself indicative of special design?  If so, it appears to me that he is logically bound to maintain that the long line of seaweed, the shells, the stones and the little heap of garnet sand upon the sea-coast are all equally indicative of special design.  The general laws relating to specific gravity are at least of as much importance in the economy of nature as are the general laws relating to specific differentiation; and in each illustration alike we find the result of the operation of known physical causes to be that of selection.  If it should be argued in reply that the selection in the one case is obviously purposeless, while in the other it is as obviously purposive, I answer that this is pure assumption.  It is perhaps not too much to say that every geological formation on the face of the globe is either wholly or in part due to the selective influence of specific gravity, and who shall say that the construction of the earth’s crust is a less important matter in the general scheme of things (if there is such a scheme) than is the evolution of an eye?  Or who shall say that because we see an apparently intentional adaptation of means to ends as the result of selection in the case of the eye, there is no intention served by the result of selection in the case of the sea-weeds, stones, sand, mud?  For anything that we can know to the contrary, the supposed intelligence may take a greater delight in the latter than in the former process.