Another of Mr. Spencer's questions is, "Why, if typical uniformity was to be maintained, does the number of sacral vertebræ vary within the same order of birds?" The answer is the same as that which assigns a reason for all other variations in the skeleton of animals of the same order but of different varieties, namely, the special utility of the variations in the number of sacral vertebræ that would be most useful in that variety. The typical uniformity maintained is a uniformity in the process of growth and formation, down to a point where the variations are to come in which mark one animal from another; and I have more than once had occasion to suggest that the typical uniformity, and its adaptation to the varying requirements of different beings, is the highest kind of moral evidence of the existence, wisdom, and power of a supreme artificer, and that it militates so strongly against the doctrine of evolution that, without more proof than can possibly be claimed for that doctrine, we ought not to yield to it our belief. The theory that the original condition of all vertebrate animals was that of separate movable segments throughout the spinal column, as it is now in fishes and some reptiles, and that in the evolution of the higher vertebrates out of these lower forms, certain of these movable segments were rendered less movable with respect to each other by the mechanical conditions to which the successive generations were exposed, until at length the sacrum was formed, is undoubtedly a theory that excludes all design of an infinite artificer, and all intention whatever. It is a theory which relegates the most special contrivances and the most exact adaptations to the fortuitous operation of causes that could not have produced the variations of structure and at the same time have preserved the typical uniformity. It is certainly a theory which we should not apply to the works of man, if we were investigating products which seemed to be the result of human ingenuity and skill, but of the origin of which we had no direct evidence. In such a case, we should not shut our eyes to the proofs of intentional variations and adaptation, or, if we did, our speculations would not be likely to command the assent of cultivated and sound reasoners. We may treat the works of Nature by a system of logic that we should not apply to the works of man, but if we do, we shall end in no tenable results. The principal and in fact the only essential distinction to be observed between the works of Nature and the works of man relates to the degree of power, intelligence, and skill in the actor. If we assume, as we must, that in the one case there was an actor, applying will, intelligence, and power to the properties of matter, and molding it into certain products and uses, and that in the other case there was no actor, but that all products and results are but the ungoverned effects of what are called natural laws in contradistinction to all