Well, the answer to be made is that only upon the hypothesis of special creation can this analogy hold: on the hypothesis of evolution by physical causes the evidence in the two cases is _not_ equal. For, upon this hypothesis we have the eye beginning, not as a ready-made structure prepared beforehand for the purposes of seeing, but as a mere differentiation of the ends of nerves in the skin, probably in the first instance to enable them better to discriminate changes of temperature. Pigment having been laid down in these places the better to secure this purpose (I use teleological terms for the sake of brevity), the nerve-ending begins to distinguish between light and darkness. The better to secure this further purpose, the simplest conceivable form of lens begins to appear in the shape of small refractive bodies. Behind these sensory cells are developed, forming the earliest indication of a retina presenting a single layer. And so on, step by step, till we reach the eye of an eagle. 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