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the teeth. What they stood in need of, was a strong, hard, insensible, desensive coat: and exactly such a covering is given to them, in the ivory enamel which adheres to their surface.
2. The scarf-skin, which clothes all the rest of the body, gives way, at the extremities of the toes and fingers, to nails. A man has only to look at his hand, to observe with what nicety and precision, that covering, which extends over every other part, is here superseded by a different substance and a different texture. Now, if either the rule had been necessary, or the-deviation from it accidental, this effect would not be seen. When I speak of the rule being necessary, I mean the formation of the skin upon the surface being produced by a set of causes constituted without design, and acting, as all ignorant causes must act, by a general operation. Were this the case, no account could be given of the operation being suspended at the fingers' ends, or on the back par^of the singers, and not on the fore part. On the other hand; if the deviation were accidental, an error, an anomalifm; were it any thing else than settled by intention; we should meet with
nails upon other parts of the body. They would be scattered over the surface, like warts or pimples.
3. All the great cavities of the body are enclosed by membranes except the skull. Why mould not the brain be content with the fame covering as that which serves for the other principal organs of the body? The heart, the lungs, the liver, the stomach, the bowels, have all soft integuments, and nothing else. The muscular coats are all soft and membranous. I can see a reason for this distinction in the final cause, but in no other. The importance of the brain to life, (which experience proves to be immediate,) and the extreme tenderness of its substance, make a solid case more necessary for it, than for any other part: and such a case, the hardness of the skull supplies. When the smallest portion of this natural casquet is lost, how carefully, yet how impersectly, is it replaced by a plate of metal? If an anatomist should fay, that this bony protection is not confined to the brain, but is extended along the course of the spine, I answer, that he adds strength to the argument. If he remark, that the chest also is fortified by bones, I reply, that I would have alledged this inQ„ stance stance myself, if the ribs had not appeared subservient to the purpose of motion, as well as of desence. What distinguishes the skull from every other cavity is, that the bony covering completely surrounds its contents, and is calculated, not for motion, but solely for desence. Those hollows, likewise, and inequalities, which we observe in the inside of the skull, and which exactly fit the folds of the brain, answer the important designs of keeping the substance of the brain steady, and of guarding it against concussions.
Whenever we find a general plan pursued, yet with such variations in it, as are, in each cafe, required by the particular exigency of the subject to which it is applied, we possess, in such plan and such adaptation, the strongest evidence, that can be afforded, of intelligence and design; and evidence, which the most completely excludes every other hypothesis. If the general plan proceeded from any fixed necessity in the nature of things, how could it accommodate itself to the various wants and uses which it had to serve, under different cir cumstances, and on different occasions? Arkwright's mill was invented for the spinning of cotton. We see it employed for the spinning of wool, flax, and hemp, with such modifications of the original principle, such variety in the fame plan, as the texture of those difserent materials rendered necessary. Of the machine's being put together with design, 0^,2 if if it were possible to doubt, whilst we saw it only under one mode, and in one form; when we came to observe it in its different applications, with such changes of structure, such additions, and supplements, as the special and particular use in each case demanded, we could not refuse any longer our assent to the proposition, " that intelligence, properly and strictly so called (including under that name, foresight, consideration, reference to utility,) had been employed, as well in the primitive plan, as in the several changes and accommodations which it is made to undergo."
Very much of this reasoning is applicable to what has been called Comparative Anatomy. In their general economy, in the outlines of the plan, in the construction as well as offices of their principal parts, there exists, between all large terrestrial animals, a close resemblance. In all, life is sustained, and the body nourished, by nearly the fame apparatus. The heart, the lungs, the stomach, the liver, the kidneys, are much alike in all. The fame fluid (for no distinction of blood has been observed) circulates through their vessels, and yearly in the fame order. The fame cause,