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or what; how much, or how often. In all these things appetite is a much better guide than reason. Were reason only to direct us in this matter, its calm voice would often be drowned in the hurry of business, or the charms of amusement. But the voice of appetite rises gradually, and at last becomes loud enough to call off our attention from any other employment. Without our appetites, even supposing mankind inspired with all the knowledge requisite for answering their ends, the race of men must have perished long ago; but by their means, whether man be savage or civilized, knowing or ignorant, virtuous or vicious, the race is continued from one generation to another.

"By the same means, the tribes of brute animals, from the whale that ranges the ocean to the least microscopic insect, have been continued from the beginning of the world to this day."*

I have thus enumerated a few of those actions in mankind which suggested themselves to Dr. Reid, as appertaining to the province of Instinct. It is true, they appear somewhat different from the examples that have been given of pure instinct in the brute; and it is possible, that many may question how far some of them belong to this class of animal operations. Some perhaps may refer them entirely to mechanical impulse. But whether the moving cause act in the first instance by mechanical impression; or whether the term Instinct deserves to be applied

* See Reid's Essays, vol. 3. Essay 3. Chap. 1.

to them or not; they certainly do not come within the province of Reason; for they are common to some of the lowest of the brute animals with man; and so far, the conclusion, that they are independent of conscious intention or deliberation, must remain unshaken.

Admitting with Dr. Priestley, that none of these actions are instinctive, and that they are wholly to be explained on mechanical principles, it is easy to see that we must come at last to precisely the same conclusion respecting a divine Intelligence, whether we suppose that it acts in the first instance on mechanical or on vital powers. But, one would think, it was now sufficiently settled, that none of the acts of any living organised being can be explained on purely mechanical principles, without some inherent vital Therefore energy, communicated by the Creator.

the acts of breathing and sucking, though they may implicate some degree of mechanical agency, are in their nature eminently vital, and have no more to do with outward instruction than the germination of a seed has to do with it. Consequently they arise from an instinctive physical impulse directed by Supreme Wisdom.

It appears, therefore, that we have no need to look to the lower animals in order to feel the conviction that many operations, marking singular intelligence, are going forward in the animal economy, which are not under the direction of Reason, and which we are unable to comprehend. Neither are we under the

necessity of being confined to doubtful instances in the human system: for, to rely on these would only weaken our argument, if they were the best or only ones we could adduce. But it is certain that the most important functions of the human body, as digestion, assimilation, nutrition, absorption, secretion, circulation, respiration, and many others, are performed by instinctive living actions, with the operation of which our reason or volition has no immediate concern. Science has pointed out to us, obscurely, the mechanism or fabric of the organs on which some of these functions depend. I say, obscurely, for every fresh insight we get by the microscope or by injection, only shews a new series of wonders in their structure. But about the mode of their working we are as ignorant, as if we knew nothing at all of the mechanism.

In truth, the only material difference that seems to exist between these instinctive actions and others in principle, is this, that they are internal and almost invisible, except by their effects; whereas the others properly called Instincts, display themselves openly to our view.

The caterpillar, when shaken off the leaves of a tree, that returns and crawls up the trunk and along the branches till it regains the situation best fitted for its present support and future transformation, does not exhibit a phenomenon differing much in principle from the stomach that digests, or the gland that secretes, or the lacteal that absorbs. The chief

difference is, that the latter are parts of a system, and the insect to which I have alluded constitutes a whole or entire self-moving structure. But the perfection with which the several organs of the body discharge their functions, when in a state of health, is as worthy of admiration as any phenomenon without us among the insect tribes. And we may presume, as they are none of them the works of man, that the evidence of wisdom should equally appear in one class of phenomena as in another-consequently, the perfection and efficiency of the acts as well as of the divine workmanship.

When a bone is broken, the surgeon does not in fact produce a union between the fractured ends. That process is effected by a power of self-restoration in the human body, to which his skill cannot reach ; and because he can go no farther, he calls it a law of the animal economy. He may, indeed, aid and assist, or he may thwart: so much power has been given to man, to good or to evil, over the body as well as the mind: but the ultimate efforts are not his own, nor can he wholly command their obe


Hence has arisen the term vis medicatrix naturæ, or healing power of nature, to designate a power implanted in the bodily constitution to preside over all its functions, vital and natural, for its support in health, and its preservation from injury, a principle, powerfully active in effect, whether the term be admitted or rejected, and under all its appellations

meaning the same thing, though the cause be unknown. Therefore, whether it be called the quas of Hippocrates, the archæus of Van Helmont, the anima of Stahl, or the vis medicatrix of Cullen; whether it be dignified as the vital principle or degraded to mere mechanical and organic impulse; it is used to imply a mysterious innate faculty or power, from the moment of birth,-even from the first rudiments of living action,-ever watching and sustaining the body in its struggles with the various accidents of time to the last hour of human existence, when by an irreversible decree its efforts must cease.

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