Now we have got our animal, not only furnished with what is wanted for its im mediate existence, but also with the pow er of spinning out that existence to an in definite length of time. But its duration, we may presume, must necessarilybc : for as it is nourished, grows, and is raised up to its full strength and perfec tion, so it must, in time, in common with all material things, begin to decay, and then hurry on to final ruin. Hence we see the necessity of a scheme for renova tion. Accordingly, a wise Providence, to perpetuate as well as to preserve his work, besides giving a strong appetite for life and self-preservation, has made ani mals male and female, and given them such organs and passions as will secure the propagation of the species to the end of the world.
Thus we sec, that by the very imper fect survey which human reason is able to take of' this subject, the animal man must necessarily be complex in his cor poreal system, and in its operations, Ile must have one great and general system, the vascular,bmnehing through the whole for 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 those parts.
Besides these primary and general sys tems, he requires others, which may be more local or confined : one for strength, support, and protection ; the bony corn pages : another for the requisite motions of the parts among themselves, as well as for moving from place to place ; the mus cular part of the body : another to pre pare nourishment for the daily recruit of the body; the digestive organs : and one for propagating the species ; the organs of generation.
In taking this general survey of what would appear, a priori, to be necessary for adapting an animal to the situations of humanity, we observe, with great satis faction, that man is in fact made of such systems, and for such purposes. He has them all, and he has nothing more, except the organs of respiration. Breathing we cannot account for a priori, we only know that it is in fact essential to life. Not withstanding this, when we see all the other parts of the body, and their func tions, so well accounted for, and so wisely adapted to their several purposes, we can not doubt that respiration A so likewise. We find, in fitet, that the blcapd in its cir culation becomes altered in its properties, and that these arc renewed by the ab sorption of the oxygenons or pure part of the atmosphere in the lungs ; we find also,.that this function is the means of
supporting the temperature ofthe animal. The use and necessity of all the differ ent systems in a man's 'body is not more apparent, t han the wisdom and contrivance which has been exerted in putting them all into the most compact and convenient form, and in disposing them so, that they shall mutually receive and give helps to one another, and that all, or many of the parts, shall not only answer their princi pal end or purpose, but operate success fully and usefully in many secondary ways.
If we understand and consider the whole animal machine in this light, and compare it with any machine, in which hu man art has done its utmost, suppose the best constructed ship that ever was built, we shall be convinced, beyond the possi bility of doubt, that there is intelligence and power far surpassing what humanity can boast of.
In making such a comparison, there is a peculiarity and superiority in the natu ral machine, which cannot escape obser vation. It is this; in machines of human contrivance or art, there is no internal power, no principle in the machine itself, Ely which it can alter or accommodate it self to any injury which it may suffer, or make up any injury which is reparable. But in the natural machine, the animal body, this is most wonderiully provided for by internal powers in the machine it self, many of which are not more certain or 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 bro ken bone is made firm again by callus ; a dead part is separated and thrown off; noxious juices are driven out by some of the emunetories ; a redundancy is remo ved by some spontaneous bleading ; bleeding naturally stops of itself; and a great loss of blood, from any cause, is in some measure compensatedby a contract i ng power in the vascular system, which accommodates the capacity of the vessels to the quantity contained. The stomach gives information when the supplies have been expended, represents with great ex actness the quantity and quality of what is wanted in the present state of the ma chine, and in proportion as she meets with neglect, rises in her demand, urges her petition in a louder voice, and with more forcible arguments. For its protection, an animal body resists heat and cold in a very wonderful and preserves an equal temperature in a burning and in a free zing atmosphere.