is carried into the thoracic duct, and there mixed with a large portion of the chyle and lymph, by which its acrimony is fheathed and diluted, or its chemical properties changed, before it enters the mass of blood? For the absorbents of the skin, and of the intestines, fhould feem to require a capacity to bear the ftimulus of those extraneous bodies to which, in both fituations, they are expofed.

III. Medicines introduced into the course of circulation may affect the general conftitution of the fluids; produce changes in their particular qualities; fuperadd new ones; or counteract the morbific matter, with which they may be occafionally charged. By obfervations on the hæmorrhages, which have been fuftained without destruction to life; from experiments made on animals, by drawing forth all their blood; and by a compution of the bulk of the arteries and veins*; the mafs of circulating fluids has been estimated at fifty pounds, in a middle-fized man; of which twenty-eight pounds are supposed to be red blood. Fluids, bearing fo large a properties to the weight of the whole body, have affuredly very important offices in the animal œconomy. Endued with the common properties of other fluids, they are fubject to mechanical laws; being variously compounded,

* Vid. Halleri Prim. Lin. fe&t. CXLIX.

they are incident to chemical changes; and, as they are contained in a living vascular system, their motions become fubject to the influence of nervous energy.

But the profecution of this fubject will exceed the bounds of the prefent evening's difcuffion: And I fhall referve what I have further to advance upon it to fome future meeting of the Society,

OBSERVATIONS concerning the VITAL PRINCIPLE; by JOHN FERRIAR, M. D.

READ FEBRUARY 7, 1787.

Quibus ipfis noftrum (fc. humanum) ingenium optimè poteft cognofci, quod vilia, fenfibus obvia et facilia, ac fimpliciffima defpicit; ad ignota vero, obfcura et magnifica magno impetu fertur. HOFFMAN.

PHILOSOPHERS have generally supposed

the human body to poffefs a living power, independent of the mind. This opinion arose at a very early period, and prevailed, with little interruption, till the origin of the eclectic philofophy; the revival and confirmation of the doctrine have been attempted, by fome eminent phyfiologifts of our own times. The doctrines of pneumatology have, indeed, little influence

on

on medical theories at prefent, but the opinion of a vital principle is chiefly directed, to explain thofe actions of the living body, both in health and difeafe, which become the most important objects of a phyfician's attention; and as it seems calculated to restore the theory of occult qualities, under the fpecious title of principles, fhould it extend itself among perfons lefs enlightened than its present defenders, a view of its foundation, and its connection with facts, becomes defirable.

The immateriality of the foul was admitted. by most of the ancient philofophers*, but the reciprocal action of the foul and body on each other, in the phænomena of fenfation and voluntary motion, were not easily explained on that fuppofition. To get rid of this difficulty, Plato, improving perhaps on the opinion attributed to Pythagorast, propofed that of a plastic nature, incorporeal indeed, but without confcioufnefs, and forming the medium between the foul and body. This doctrine appears to have been variously modified by different fects, but believed, to a certain extent, by all till the time of Ariftotle. Mr. Barthez, in his learned

That is its diftinction from matter, though not in the fenfe of the modern immaterialists.

+ Of an Anima Mundi, from which the fouls of men were emanations. Vell. in Cic. de Nat. Deor.

Cudworth's Intellect. Syft. p. 158, 165, 166.

treatise

treatise on this subject, alledges that the Stoics held the existence of a vital principle*. Ariftotle is reprefented, by fomet, as following the Platonic theory, because he diftinguished the mind into the intellectus agens et patiens; but he is vindicated against former affertions of the fame kind, by Sennertus, who explains his meaning to be, that the mind operates in two distinct ways, in confequence of being affected by two diftinct claffes of perceptions; confequently, that the distinction implies only a differentia in anima: Intellectum agentem et patientem non realiter et effentialiter, fed ratione tantum diftingui. It appears, however, that most of the Peripatetics understood Ariftotle's expreffions in a sense favourable to the plastic nature. Physicians had always admitted the existence of the vital principle, under the title of the calidum innatum. Some of the first reftorers of letters alfo, adopted this opinion, with different modifications §; and during a confiderable part of the laft century, a regular fyftem

* Nouv. Elem. de L'Homme. C. II.

+ Cudworth, p. 165. & feq.

Sunt plurimi, qui intellectum agentem, vel deum, vel alium aliquem demonem feu intelligentiam, homini affiften. tem ftatuunt. Verum enimvero et ab Ariftotele et a veritate horum opinio aliena videtur. Epit. Phyfic. p. 82. Sennert. fub titulo. Barthez Nouv. Elem. chap. II. Vid. Brucker. Hift. Crit. Philof. T. V. p. 50, 136, prevailed,

943.

prevailed, by which the vital principle was reckoned the efficient caufe of generation and existence, in all animals and plants. It then took the name of the anima vegetans *. Paracelfus changed this term, in his philofophy, for that of fidereal fpirit, which he believed to be equally independent of the body and the mind †, and to descend from the firmament, as the rational foul proceeded from the Deity. This doctrine was very serviceable to the demonologists . Van Helmont, among other improvements of the Paracelfian system, suggested the theory of the Archeus, without venturing to affert the unity of the rational and living fouls §. The actions of the Archeus were afterwards reduced, by Stahl, to operations of the rational foul; but Defcartes appears to have been the first modern philofopher, who rejected the feparate existence of the vital principle, under all denominations. He availed himself of the progress which was made in the nervous phyfiology not long before, by Willis and others, to form an hypothefis of the vital functions, founded on the fuppofition of the

* Alfted. Encyclop. T. I. p. 603.

+ Brucker. T. V. p. 324. Mor. Antid. adv. Atheifmum.

ations.

1 Id. IV. Glanville's Confider

Barthez, chap. I. He fets Lord Verulam at the head of the modern fupporters of the vital principle, p. 23.