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places, unite them, and at the same time allow them tɔ move a little upon one another; these purposes are answered by the cellular membrane, or edipose substance.
There must be an outward covering over the whole apparatus, both to give it compactness, and to defend it from a thousand injuries; which, in fact, are the very purposes of the skin and other integuments.
Say, what the various bones so wisely wrought?
Lastly, the mind being formed for society and intercourse with beings of her own kind, she must be endued with powers of expressing and communicating her thoughts by some sible marks or signs, which shall be both easy to herself, and admit of great variety. And accordingly she is provided with the organs and faculty of speech, by which she can throw out signs with amazing facility, and vary them without end.
Thus we have built up an animal body, which would seem to be pretty complete; but as it is the nature of matter to be altered and worked upon by matter, so in a very little time such a living creature must be destroyed, if there is no provision for repairing the injuries which she must commit upon herself, and those which she must be exposed to from without. Therefore a treasure of blood is actually provided in the heart and vascular system, full of nutritious and healing particles; fluid enough to penetrate into the minutest parts of the animal; impelled by the heart, and conveyed by the arteries, it washes every part, builds up what was broken down, and sweeps away the old and useless materials. Hence we see the necessity or advantage of the heart and arterial system.
What more there was of the blood than enough to repair the present damages of the machine, must not be lost, but should be returned again to the heart; and for this purpose the venous system is provided. These requisites in the animal explain the circulation of the blood, a priori.*
All this provision, however, would not be sufficient; for the store of blood would soon be consumed, and the fabric would break down, if there was not a provision made by fresh supplies. These we observe, in fact, are profusely scattered round he in the animal and vegetable kingdoms; and she is furnished with hands, the fittest instruments that could be conuived for gathering them, and for preparing them in their varieties for the mouth.
* This subject will be more fully explained hereafter.
But these supplies, which we call food, must be considerably changed; they must be converted into blood. Therefore she is provided with teeth for cutting and bruising the food, and with a stomach for melting it down; in short, with all the organs subservient to digestion: the finer parts of the aliments only can be useful in the constitution; these must be taken up and conveyed into the blood, and the dregs must be hrown off. With this view, the intestinal canal is provided. it separates the nutritious parts, which we call chyle, to be conveyed into the blood by the system of the absorbent vessels; and the coarser parts pass downwards to be ejected.
We have now got our animal not only furnished with what is wanting for immediate existence, but also with powers of protracting that existence to an indefinite length of time. But its duration, we may presume, must necessarily be limited; for as it is nourished, grows, and is raised up to its full strength and utmost perfection; so it must in time, in common with all material beings, begin to decay, and then hurry on into final ruin.
Thus we see, by the imperfect survey which human reason is able to take of this subject, that the animal man must necessarily be complex in his corporeal system, and in its operations.
He must have one great and general system, the vascular, branching through the whole circulation: another, the nervous, with its appendages-the organs of sense, for every kind of feeling: and a third, for the union and connection of. all these parts.
Besides these primary and general systems, he requires others, which may be more local or confined: one, for strength, support, and protection,-the bony compages: another, for the requisite motions of the parts among themselves, as well as for moving from place to place, the muscular system: another to prepare nourishment for the daily recruit of the body, -the digestive organs.
Dr. Paley observes, that, of all the different systems in the human body, the use and necessity are not more apparent, than the wisdom and contrivance which have been exerted, in putting them all into the most compact and convenient form: in disposing them so, that they shall mutually receive from, and give helps to one another: and that all, or many of the parts, shall not only answer their principal end or purpose, but operate successfully and usefully in a variety of secondary ways. If we consider the whole animal machine in this light, and compare it with any machine in which human art has exerted its utmost, we shall be convinced, beyond the possibility of doubt, that there are intelligence and power far sur passing what humanity can boast of.
Que superiority in the natural machine is peculiarly striking. -In machines of human contrivance or art, there is no internal power, no principle in the machine itself, by which it can alter and accommodate itself to injury which it may suffer, or make up any injury which admits of repair. But in the na tural machine, the animal body, this is most wonderfully provided for, by internal powers in the machine itself; many of which are not more certain and obvious in their effects, than they are above all human comprehension as to the manner and means of their operation. Thus, a wound heals up of itself; a broken bone is made firm again by a callus; a dead part is separated and thrown off; noxious juices are driven out by some of the emunctories; a redundancy is removed by some spontaneous bleeding; a bleeding naturally stops of itself; and the loss is in a measure compensated, by a contracting power in the vascular system, which accommodates the capacity of the vessels to the quantity contained. The stomach gives intimation when the supplies have been expended; represents, with great exactness, the quantity and quality, of what is wanted in the present state of the machine; and in proportion as she meets with neglect, rises in her demand, urges her petition in a louder tone, and with more forcible arguments For its protection, an animal body resists heat and cold in a very wonderful manner, and preserves an equal temperature in a burning and in a freezing atmosphere.
A farther excellence or superiority in the natural machine, if possible, still more astonishing, more beyond all human comprehension, than what we have been speaking of, is the distinction of sexes, and the effects of their united powers. Besides those internal powers of self-preservation in each individual, when two of them, of different sexes, unite, they are endued with powers of producing other animals or machines. like themselves, which again are possessed of the same powers of producing others, and so of multiplying the species without end These are powers which mock all human invention or imitation. They are characteristics of the Divine Architect.Thus far Paley.
Galen takes notice, that there are in the human body above 600 muscles, in each of which there are, at least, 10 several intentions, or due qualifications, to be observed; so that, about the muscles alone, no less than 6000 ends and ains are to be attended to! The bones are reckoned to be 284; and the distinct scopes or intentions of these are above 40—in all about 12,000! and thus it is, in some proportion, with all the other parts, the skin, ligaments, vessels, and humours; but more especially with the several vessels, which do, in regard to their great variety, and multitude of their several intentions very much exceed the homogeneous parts.