The organic powers of the human body naturally divide themselves into two principal classes. The first class embraces those which no known laws and phenomena of the physical world enable us to comprehend; and to these belong the sensibility of the nerves and the irritability of the muscles. Inasmuch as it has hitherto been impossible to penetrate the economy of the invisible, men have sought to interpret this unknown mechanism through that with which they were already familiar, and have considered the nerves as a canal conducting an excessively fine, volatile, and active fluid, which in rapidity of motion and fineness was held to excel ether and the electric spark. This fluid was held to be the principle and author of our sensibility and power of motion, and hence received the name of the spirit of life. Further, the irritability of the muscles was held to consist in a certain effort to contract themselves on the touch of some external provocation. These two principles go to form the specific character of animal organism.
The second class of powers embraces those which we can account for by the universally-known laws of physics. Among these I reckon the mechanism of motion, and the chemistry of the human body, the source of vegetable life. Vegetation, then, and animal mechanism, thoroughly mingled, form the proper physical life of the human body.
§ 4.—Animal Life.
This is not yet all. Since loss or misfortune, when it occurs, falls more or less within the will-power of the spirit, the spirit must be able to make some compensation for it. Further, since the body is subjected to all the consequences of this connection, and in the circle of circumstances is exposed to countless hostile forces, it must be within the power of the soul to protect the body against these harmful influences, and to bring it into such relations with the physical world as shall tend most to its preservation. The soul must therefore be conscious of the present evil or good state of its organs; from a bad state it must draw dissatisfaction, from a good state satisfaction, so that it may either retain or remove the condition, seek it or fly from it. Here then we have the organism at once and closely linked to the sensational capacity, and the soul drawn into the service of the body. We have now something more than vegetation, something more than a dead model and the mechanism of nerves and muscles. Now we have animal life.[[19]]
A healthy condition of our animal life is, as we know, most important for the healthy condition of our spiritual life; and we dare never ignore the animal life so long as we are not quit of it. It must therefore possess a firm foundation, not easily moved; that is, the soul must be fitted and prepared for the actions of our bodily life by an irresistible power. Were then the sensations of our animal loss or well-being to become spiritual perceptions, and had they to be created by thought, how often would the soul be obscured by the overwhelming blaze of passion; how often stifled by laziness and stupidity; how often overlooked in the absorptions and distractions of business! Further, would not, in this case, the most perfect knowledge of his economy be demanded of the animal man—would not the child need to be a master in a branch of knowledge in which, after fifty years of investigation, Harvey, Boerhaave, and Haller were only beginners? The soul could thus have positively no idea of the condition she was called upon to alter. How shall she become acquainted with it? how shall she begin to act at all?
§ 5.—Animal Sensations.
So far we have met with such sensations only as they take their rise in an antecedent operation of the understanding; but we have now to deal with sensations in which the understanding bears no part. These sensations, if they are not exactly the expression of the present state of our organs, mark it out specifically, or, better, accompany it. These sensations have quickly and forcibly to determine the will to aversion or desire; but, on the other hand, they are ever to float on the surface of the soul, and never to extend to the province of the reason. The part, accordingly, played by thought, in the case of a mental perception, is here taken up by that modification in the animal parts of us which either threatens the destruction of the sensation or insures its duration: that is, an eternal law of wisdom has combined with that condition of the machine which confirms its welfare, a pleasant emotion of the soul; and, on the other hand, with that condition which undermines it and threatens ruin, an unpleasant emotion is connected; and this in such a manner that the sensation itself has not the faintest resemblance to the state of the organs of which it is the mark. Animal sensations have, on this showing, a double origin: (1) in the present state of the machine; (2) in the capacity or faculty (of sensation).
We are now able to understand how it is that the animal sensations have the power to drive the soul with an irresistible tyranny in the direction of passionate action, and not seldom gain the upper hand in a struggle with those sensations which are most purely intellectual. For these last the soul has produced by means of thought, and therefore they can by thought be solved or even destroyed. Abstraction and philosophy have this power over the passions, over opinions—in short, over all the situations of life; but the animal sensations are forced upon the soul by a blind necessity, by a stern mechanical law. The understanding, which did not create them, likewise cannot dissolve them and make them as if they were not, though by giving an opposite direction to our attention it can do much to weaken their power and obscure their pretensions. The most stubborn stoic, lying in the agony of the stone, will never be able to boast that he did not feel its pain; but, lost in the consideration of the end of his existence, he will be able to divide his whole power of sensation and perception, and the preponderating pleasure of a great achievement, which can subordinate even pain to the general welfare, will be victorious over the present discomfort. It was neither absence of nor annihilation of sensation that enabled Mucius, while he was roasting his hand in the fire, to gaze upon the foe with the Roman look of proud repose, but the thought of great Rome in admiration of his deed. This it was that ruled in his soul, and kept it grandly self-possessed, so that the terrible provocation of the animal pain was too slight to disturb the equal balance of his nature. But not on this account was the pain the Roman suffered less than it would have been in the case of the most effeminate voluptuary. True enough, the man who is accustomed to pass his days in a state of confused ideas will be less capable of manly action, in the critical moment of sensuous pain, than he who lives persistently among ideas distinct and clear; but, for all that, neither the loftiest virtue, nor the profoundest philosophy, nor even divine religion, can save a man from the result of a necessary law, though religion can bless her servants even at the stake, and make them happy as the pile gives way.
The wisest purpose is served by the power which the animal sensations possess over the perceptive faculty of the soul. The spirit once initiated in the mysteries of a higher pleasure would look with disdain upon the motions of its companion, and would pay no heed to the poor necessities of physical life, were it not that the animal feeling compelled it to do so. The mathematician, soaring in the region of the infinite, and dreaming away reality in a world of abstractions, is roused by the pang of hunger from his intellectual slumber; the natural philosopher, dismembering the solar system, accompanying through immeasurable space the wanderings of the planets, is restored by the prick of a needle to his mother earth; the philosopher who unfolds the nature of the Deity, and fancies himself to have broken through the fetters of mortality, returns to himself and everyday life when the bleak north wind whistles through his crazy hut, and teaches him that he stands midway between the beast and the angel.
Against an excess of the animal sensations the severest mental exertion in the end possesses no influence; as they continue to grow stronger, reason closes her ears, and the fettered soul moves but to subserve the purposes of the bodily organization. To satisfy hunger or to quench thirst man will do deeds at which humanity will shudder: against his will he turns traitor or murderer—even cannibal:—