Barthez has enjoyed a much higher reputation on the Continent than in this country, where, indeed, his writings are but little known. The work which has chiefly contributed to establish his fame, and which contains the developement of his peculiar opi nions on physiology, is the Nouveaux Lumens de la Science de Homme. It is not written, however, with the simplicity and clearness which might have been expected from one who had been in the constant habit of instructing others, and whose lectures were generally admired as possessing those qualities in an eminent degree. He appears to have been early im pressed with the fhtility of all the theories that had been hitherto advanced in explanation of the phenomena presented by living beings, and to have been incited to the bold attempt of raising a new system upon more rational and solid foundations. In the prelimi nary discourse to the work we have alluded to, he lays down, with great correctness, the fundamental principles of the method of philosophizing in the na tural sciences. The common object of these sciences he states to be the research into the causes of natu ral phenomena, in as far as they can be learned by experience ; and shows that we have no direct know ledge of these causes, except as manifested by stich of their effects as we perceive. In the infancy of philosophy, numerous causes are assigned to these "pit** *Sae ; Itattag *draftee -nrea, and in proportion as the siedlarity of effects, which had been retbered to different causes, is ease: Wished, the number of these assigned causes beeenres more and more circantecribed, Although the real nature of the agents prodncing those 'general facts, to which we ultimately arrive by ibllovnng this me thod of indamion, be absolutely unknown, yet, in reasoning coweerning them, we find it convenient to express them bya•narne, as' Wilsey were really known to us ; in the same way eb in prosecuting an alge braical ealculus; we name misplay characters to ex press the tubnown, as well as the given quantities. Brie the distinction ohotild ever be kept in vie* ; and • •should err greatly were we to imagine that we could derive any Ultimate advantage by the imbed .
tution of other symbols, which differed from them only in appearance, or which involved the admission of some hypothetical principle.
Such are the rules by which he professes to be guided in his own investigations ; end such the tests by which he examinee and passes judgment upon the doctrines of the different sects of Animists, Mecha nicians, and' Chemists, which had successively pie veiled before him in theathools of medicine, and also upon the more recent doctrine of the Solidists,•which was then becoming fbthienable. In the reviesiwhich he gives of the opinions of the several leaders of these sects, he displays an accurate acquaintance With the wide circle of medical literature. But, in the prosecution of his plan, he shows, what the ex ample of others has so often proved,. that it is easier to overthrow than to build a system ; and 'he evi dently violates the Strict principles of and of cautious Hesitation to the province of philosophi cal inquiry, which he had prescribed, when he en gages in the task himself. He sets out with endea vouring to' esti*** a gradation' among the camas which' in producing motion. The simplest of these. is the lbece of impulsion ; that of gravitation appears to• him less simple ; and still less so those of electricity and maghedens. The pliettiples which regulate cheridad.aifinitito are mere complicated, as Well as those whichare concerned in the stsdlieau tion of bodies. Hitt the • threes which produce the phenomena df living vegetables and 'animals are of a mere Order, and tat all *eatable, according to -Mathes, tb 'crest, which he denornirrates the shed prineipk, erlirincipk Having es tablished 'this dogma,. he proceeds to 'dikes* a 'vs
riety of abstruse questions that have been 'agitated on the subject, seen as whether the has an independent existence, distinct from the or - &Mixed 'body Which It animates ; and whether it be • modificatton. of the steti of rational sided. He gives an elaborate historical sketch' of the opinions Of philosophers fresh The•earliest dine* redperebng the' nature ofbfe, ttacibg the different sentiments enter.' tabled 'Ely the fbilowers'of Aristotle and Descartes, together with the Shifted an•'Beettimarians, on the one hand ; and those of Pythagoras, • df Plato, and the sect of Stoics, on theother : the Antler net ac knowledging an principle of life distinct frees tither matter or tided— and the latter edesittleg such a principle lid* body. A 'shbe oho of philosophers* noticed, at the head of Which.tm places bacon, and with which he associates Leibnitz, Cudworth, Van Hehnont, and who have cognised the existence of a vital power different from. the ordinary physical properties of matter, and at the same time totally distinct from the soul. After expending much useless argument in refutation of the Stahlian doctrine of the identity of the vital with the thinking principles, and devoting a long chapter to the consideration of doubts as to our means of de ciding the question, he shows himself strongly in clined to the belief that the principle of life is some thing which has a separate existence, distinct front any modification, either of matter or of mind. There is little doubt, indeed, that this was his firm pet suasion, as he reasons from it in many parts of his work, though he seems averse to declare it, without qualification, while he is discussing these questions. Having thus prrsottOrd, as he very aptly expresses it, this new principle of life, he appeals to it for the solution of every difficulty. it is the master key which unlocks every secret, and renders all the ope rations of the living animal body perfectly intelligible. Irritability and sensibility are at once the direct ef fects of this universal agent. All the modifications of these properties, and, in a word, every pheno Amnon of life, which is not obviously the result of phisical laws, are but so many immediate operations' of the vital principle. To this fertile source he re fers not only the ordinary muscular contractions, but also the slower and less sensible motions which piece in the iris, in the vascular system, end, in ge neral, in those parts in which no muscular strut:Wei can be discerned : Abets which he attributes to the. tonic power of the vital principle. He contends for the existence ofanother power in the de. rived from the same source ; namely, the power se elongation, after they have been contracted; a porter which he ;links quite distinct from the other me. chemical properties of the ibre,• and of whiCh the operation is exemplified in the dilatation • of the pupil,. the extension of the corpora caveman, and of the nipples, and in the'disuitole of the heart itself. Ile plumes himself more particularly upon his supposed discovery of a new species 'of forte, distinct from the Muscular power, eench he terms theftiee efixed .16 tuation, and of which he infers the existence from 'the circumstance of the tendo Achilles being ruptured, and of the patella, sad head of the or eaten being fractered, on'sovne occasions,' by an sppareatly slight exertion. Heaveils 'himself of this principle, also, of expinin'the phenomena of teirMus, and other vas modle affections.