speculations in some degree too sublime for us: the moment we launch into them, that moment we become lost, and find it necessary to return with suitable modesty to our proper province, an examination of the world around us; where, with all the aids of which we can avail ourselves, we shall still find difficulties enough to try the wisdom of the wisest, and the patience of the most persevering.

208

LECTURE X.

ON THE PRINCIPLE OF LIFE, IRRITABILITY, AND MUSCULAR POWER.

WE have distinguished organic from inorganic matter; and have characterised the former, among other differences, by its being actuated in every separate form by an internal principle, and possessed of parts mutually dependent and contributory to each other's functions. What then is this internal principle, this wonderful and ever active power, which, in some sort or other, equally pervades animals and vegetables-which extends from man to brutes, from brutes to zoophytes, from zoophytes to fucuses and confervas, the lowest tribes of the vegetable kingdom, whose general laws and phænomena constituted the subject of our last study, this fleeting and evanescent energy, which, unseen by the eye, untracked by the understanding, is only known, like its great Author, by its effects; but which, like him, too, wherever it winds its career, is perpetually diffusing around it life and health, and harmony and happiness?

I do not here enter into the consideration of a thinking or intelligent principle, or even a principle of sensation, both which are altogether of distinct natures from the present, and to which I shall intreat your attention hereafter; but confine myself entirely to that inferior but energetic power upon which the identity and individuality of the being depends, and upon a failure of which the individual

frame ceases, the organs lose their relative connexion, the laws of chemistry, which have hitherto been controlled by its superior authority, assume their action, and the whole system becomes decomposed and resolved into its primary elements.

The subject is, indeed, recondite, but it is deeply interesting it has occupied the attention of the wisest and the best of mankind in all ages; and though, after the fruitless efforts with which such characters have hitherto pursued it, I have not the vanity to conceive that I shall be able to throw upon it any thing like perfect daylight, you will not, I presume, be displeased with my submitting to you a brief outline of some few of the speculations to which it has given birth, together with the conjectures it has excited in my own mind.

Of the innumerable theories that have been started upon this subject, the three following are those which are chiefly entitled to our attention. Life is the result of a general harmony or consent of action between the different organs of which the vital frame consists.-Life is a principle inherent in the blood.—Life is a gas, or aura, communicated to the system from without. Each of these theories has to boast of a very high degree of antiquity; and each, after having had its day, and spent itself, has successively yielded to its rivals; and in its turn has re-appeared, under a different modification, in some subsequent age, and run through a new stage of popularity.

For THE SYSTEM OF HARMONY we are indebted to the inventive genius of Aristoxenus, a celebrated physician of Greece, who was at first a pupil of

Lamptus of Erythræa, afterwards of Xenophylus the Pythagorean, and lastly of Aristotle. He was most excellently skilled in music, and is supposed to have given the name of HARMONY to his system from his attachment to this science. It is an ingenious and elegant dogma, and was at one time highly fashionable at Rome as well as at Athens; and is thus alluded to and explained by Lactantius: "As in musical instruments, an accord and assent of sounds, which musicians term HARMONY, is produced by the due tone of the strings; so in bodies, the faculty of perception proceeds from a connexion and vigour of the members and organs of the frame."*

To this theory there are two objections, either of which is fatal to it. The first is, that admitting the absolute necessity of the health or perfection of every separate part to the health or perfection of the whole, we are still as much in the dark as ever in respect to the principle by which this harmonious machine has been developed, and is kept in perpetual play. The second objection, by which, indeed, it was vigorously attacked by the Epicureans, and at length completely driven from the field, is derived from observing that the health or well-being of the general system does not depend upon that of its collective organs; and that some parts are of far more consequence to it than others. Thus the mind, observes Lucretius, in his able refutation of this hypothesis, may be diseased, while the body remains unaffected; or the body, on the contrary, may lose some of its own organs, while the mind, or even the general health of the body itself, continues perfect.

v. 140.

The abbé Polignac, who, consistently with the Cartesian system, makes a very proper distinction between the principle of the mind or soul, and that of the life, enters readily into the hypothesis of Aristoxenus in regard to the latter power, though he thinks it inapplicable to the former: and Leibnitz appears to have availed himself of it as a mean of accounting for the union between the soul and body in his celebrated system, which he seems to have named, from the theory before us, the system of PRE-ESTABLISHED HARMONY. By a writer of the present age, however, M. Lusac, the doctrine of Aristoxenus seems to have been resuscitated in its fullest scope, and even to have been carried to a much wider latitude than its inventor had ever intended for the theory of M. Lusac affects to regard, not only the frame of man and other animals, but the vast frame of the universe, as a sort of musical organ or instrument; the concordant and accumulated action of whose different parts or agents he denominates, like Aristoxenus, harmony. "Concerts of music," says he, "afford a clear example: you perceive harmony in music when different tones, obtained by the touch of various instruments, excite one general sound, a compound of the whole." This observation he applies to the grand operations of nature, the irregularities of which, resulting from inundations, earthquakes, volcanoes, tempests, and similar evils, this philosopher considers as the dissonances occasionally introduced into music to heighten the harmony of the entire system. With respect to the harmony of the human frame, individually contemplated, or the concordant action of the different parts of the body, he observes, "It may be said, that