4. For example, if we suppose that men begin to speculate upon the properties of living things without acknowledging a peculiar Vital Power, but making use successively of the knowledge supplied by the study of other subjects, we may easily imagine a series of hypotheses along which they would pass. They would probably, first, in this as in other sciences, have their thoughts occupied by vague and mystical notions in which material and spiritual agency, natural and supernatural events, were mixed together without discrimination, and without any clear notion at all. But as they acquired a more genuine perception of the nature of knowledge, they would naturally try to explain vital motions and processes by means of such forces as they had learnt the existence of from other sciences. They might first have a mechanical hypothesis, in which the mechanical forces of the solids and fluids which compose organized bodies should be referred to, as the most important influences in the process of life. They might then attend to the actions which the fluids exercise in virtue of their affinity, and might thus form a chemical theory. When they had proved the insufficience of these hypotheses, borrowed from the powers which matter exhibits in other cases, they might think themselves authorized to assume some peculiar power or agency, still material, and thus they would have the hypothesis of a vital fluid. And if they were driven to reject this, they might think that there was no resource but to assume an immaterial principle of life, and thus they would arrive at the doctrine of an animal soul. Now, through the cycle of hypotheses which we have thus supposed, physiology has actually passed. The conclusions to which the most philosophical minds have been led by a survey of this progress is, that by the failure of all these theories, men have exhausted this path of inquiry, and shown that scientific truth is to be sought in some other manner. But before I proceed further to illustrate this result, it will be proper, as I have already stated, to exhibit historically the various hypotheses which I have described. In doing this I shall principally follow the History of Medicine of Sprengel. It is only by taking for my guide a physiologist of acknowledged science and judgment, that I can hope, on such a subject, to avoid errors of detail. I proceed now to give in succession an account of the Mystical, the Iatrochemical, the Iatromathematical, and the Vital-Fluid Schools; and finally of the Psychical School who hold the Vital Powers to be derived from the Soul (Psychè). CHAPTER II. SUCCESSIVE BIOLOGICAL HYPOTHESES. SECT. I. Mystical School.-In order to abbreviate as much as can conveniently be done the historical view which I have now to take, I shall altogether pass over the physiological speculations of the ancients, and begin my survey with the general revival of science in modern times. We need not dwell long on the fantastical and unsubstantial doctrines concerning physiology which prevailed in the sixteenth century, and which flowed in a great measure from the fertile but ill-regulated imaginations of the cultivators of Alchemy and Magic. One of the prominent doctors of this school is the celebrated Paracelsus, whose doctrines contained a combination of biblical interpretations, visionary religious notions, fanciful analogies, and bold experiments in practical medicine. The opinion of a close but mystical resemblance of parts between the universe and the human body, the Macrocosm and the Microcosm, as these two things, thus compared, were termed, had probably come down from the Neoplatonists; it was adopted by the Paracelsists*, and connected with various astrological dreams and cabbalistic riddles. A succession of later Paracelsists†, Rosicrucians, and other fanatics of the same kind, continued into the seventeenth century. Upon their notions was founded the pretension of curing wounds by a sympathetic powder, which Sir Kenelm Digby, among others, asserted; while animal magnetism, and the transfer of diseases from one person to another‡, were maintained by others of this school. They held, too, the doctrines of astral bodies corresponding to each terrestrial body; and of the signatures of plants, that is, certain features in their external form by which their virtues might be known. How little advantage or progress real physiology could derive from speculations of this kind may be seen from this, that their tendency was to obliterate the distinction between living and lifeless things: according to Paracelsus, all things are alive, eat, drink, and excrete; even minerals and fluids§. According to him and his school, besides material and immaterial beings, there are elementary spirits which hold an intermediate place, sylvans, nymphs, gnomes, salamanders, &c. by whose agency various processes of enchantment may be achieved, and things apparently supernatural explained. Thus this spiritualist scheme dealt with a world of its own by means of fanciful inventions and mystical visions, instead of making any step in the study of nature. Perhaps, however, one of the most fantastical of the inventions of Paracelsus may be considered as indicating a perception of a peculiar character in the vital powers. According to him, the business of digestion is performed by a certain demon whom he calls Archæus, who has his * SPR., iii., 456. + Ib., iv., 270. ‡ Ib., iv., 276. § Ib., iii. 458. PARAC., De Vita Rerum Naturalium, p. 889. abode in the stomach, and who, by means of his alchemical processes, separates the nutritive from the harmful part of our food, and makes it capable of assimilation*. This fanciful notion was afterwards adopted and expanded by Van Helmont. According to him the stomach and spleen are both under the direction of this master-spirit, and these two organs form a sort of Duumvirate in the body. But though we may see in such writers occasional gleams of physiological thought, the absence of definite physical relations in the speculations thus promulgated was naturally intolerable to men of sound understanding and scientific tendencies. Such men naturally took hold of that part of the phenomena of life which could be most distinctly conceived, and which could be apparently explained by means of the sciences then cultivated; and this was the part which appeared to be reducible to chemical conceptions and doctrines. It will readily be supposed that the processes of chemistry have a considerable bearing upon physiological processes, and might, till their range was limited by a sound investigation, be supposed to have still more than they really had; and thus a physiology was formed which depended mainly upon chemistry, and the school which held this doctrine has been called the iatrochemical school. SECT. II. The Iatrochemical School. That all physical properties, and therefore chemical relations, have a material influence on physiological results, was already recognised, though dimly, in the Galenic doctrine of the four elementary qualities. But at the time of Paracelsus, chemical action was more distinctly than before separated from other kinds of physical action; and therefore a physiological doctrine, founded upon chemistry, and freed from the extravagance and mysticism of the Paracelsists, was a very promising path of speculation. Andrew Liba* SPR., iii., 468. + Ib., iv., 302. vius* of Halle, in Saxony, Physician and Teacher in the Gymnasium at Koberg, is pointed out by Sprengel as the person who began to cultivate chemistry, as distinct from the theosophic fantasies of his predecessors; and Angelus Sala of Viennat, as his successor. The latter has the laudable distinction of having rejected the prevalent conceits about potable gold, a universal medicine, and the like. In Germany already at the beginning of the seventeenth century a peculiar chair of Chymiatria was already created at Marpurg: and many in various places pursued the same studies, till, in the middle of the seventeenth century, we come to Lemery §, the principal reformer of pharmaceutical chemistry. But we are not here so much concerned with the practical as with the theoretical parts of iatrochemistry; and hence we pass on to Sylvius and his system. The opinion that chemistry had an important bearing upon physiology did not, however, begin with Sylvius. Paracelsus, among his extravagant absurdities, did some service to medicine by drawing attention to this important truth. He used chemical principles for the explanation of particular diseases; most or all of them according to him, arise from the effervescence of salts, from the combustion of sulphur, or from the coagulation of mercury. His medicines were chemical preparations; and it was ** an undeniable advantage of the Paracelsian doctrine that chemistry thus became indispensable to the physician. We still retain a remnant of the chemical nomenclature of Paracelsus in the term tartar, denoting the stony concretion which forms on the teeth++. According to him there is a certain substance, the basis of all diseases which arise from a thickening of the juices and a collection of *SPR., iii., 550. § Ib., iv., 291. Ib., iii., 472. + Ib., iv., 281. ** Ib., iii., 482. Ib., iv., 283. || Ib., iv., 336. ++ Ib., iii., 475. |
