Such are the strange and absurd consequences to which our chemical theories inevitably lead : hut to vicy: the matter in a more serious light, let us ask to \Vila' do these reveries tend ? and what do they prove ? Only this, that some chemists are beginning to wander front the true path of science, and flitter themselves that they are making important discoveries, while they employ the phrase dicinical to eNpress things which were just as well understood before by their ordinary names. It cannot, indeed, be denied, that both chemi cal and mechanical causes are employed as operativ agents in the animal system : but, as they are always observed to act in a uniform manner, we must conclude, that, in the execution of different plans, they arc con stantly directed by some other agent, which confines their operations to certain forms, situations, magnitudes. and pet iods of life. This agent, philosophers have dis tinguished by the name of vital principle, and have de monstrated many of its properties ; while anatomists, and naturalists, as Darvey, Malpighi, Lyonct, Bonnet, Trembley, Baker, the late Mr Hunter, and many- others, have shewn its vast influence in the system, and proved, from a number of sound observations, and accorate ex periments, its peculiar powers in a great variety of dif ferent animals. When we consider what they have done, we cannot but express our surprise, that impor tant enquiries of this nature, begun and carried on by the most ingenious anatomists in Europe, should have been almost totally laid aside, and have given place to the theories of men little acquainted with the subject, who had studied the animal stmeture and economy chief ly in the closet, and Nvho had proceeded on this singu lar postulate, that there is no difference between the living and the dead states, that the principle of life does not affect the animal processes, and consequently that conclusions drawn from experiments made on the dead body, may fairly and warrantably be applied to the living.
" This species of philosophy," says Dr Hunter, " has prevailed in many parts of physiology, and makes up a great part of what has been taught as sound and tHeful physiological learning. The consequence has been, that one thing of peculiar properties and powers has been explained by another of different properties and powers. as absurdly as if colours had been explained by sounds But animal functions, generally speaking, are like nothing to be found in the works 01 art, or where there is not animation and life ; and had physiologists spent that time in making accurate observations upon animals themselves which has been thrown away upon mechan ical and chemical visions, by this time we might have understood animal principles and processes much better than we do now." In confirmation of these observations we may ask, whether, without experiment or observa tion, mechanical or chemical reasoning could ever have informed us, that a new tail will grow to the lizard, and a new head on many of the vermes, after the old ones are struck off? Or could we have been assured, on any principle of the two sciences, that when the first pha lanx in the large claw of a lobster or Tray fish, is bro ken or destroyed, the remaining phalanxes shall drop off at the fourth joint, and that then the animal, by its vital power, shall reproduce an entire limb such as the former ? Could they ever have learned, from their know ledge of angles or chemical affinities, that eight or nine successive generations of the puceron or vine-fretter, can propagate their species without the intercourse of sexes, and that after that period, the intercourse of two sexes become necessary ? Or could they have seen that the large bone of the human leg may tJ •: of disease, a new one occupy its place, and that ye .ne
person affected should all this time be able to ? These are a few specimens of that knowledge r rich the chemical philosophers would have us to desp e, or attempt to explain by their doctrine of affinities. It is unnecessary, we trust, to warn our readers of the con sequences. As the living principle has hecome the sub ject of experiment, and methods have been pointed out, by which its properties, powers, functions, and modes of action, may be ascertained, it cannot surely be prudent to leave a field of such useful enquiry, merely because it is not countenanced by the fashion of the day. Such opposition is not peculiar to the vital principle. The circulation of the blood, discovered by Harvey, was for a long time hooted and ridiculed, because the fastidious pride of anatomists, and their attachment to favourite theories, would not allow them to examine the facts on which it was founded. Chemistry experienced a similar treatment from the mathematicians, who talked with contempt of its acids and alkalies, because it seemed to threaten destruction to their diagrams, postulates, and calculations. General knowledge alone can prevent such ridiculous prejudices, which usually arise from al lowing the mind to be wholly engrossed with a favourite science. In that situation, a person must necessarily see things through a false medium. The chemist can only see his affinities ; the geometrician his mechanical laws ; and both must resemble the blind man, who, ex amining visible objects by the ear, concluded that colours were a species of sounds, and that scarlet was something like the blast of a trumpet. Nor was this misapplication of a sense attended with more palpable errors than the application of one science in explaining and illustrating the principles of another.
It is a singular and most curious fact in the history of anatomy, that geometry, chemistry, and the vital prin ciple of Iielmont and Stahl, have all, for a time, been successively rejected from physiology, because each in its turn would attempt to explain, on its own principles, the whole functions of the animal system. Should not these failures serve as a hint to modern physiologists, that the different functions of the animal system are not to be e.,plained upon one hypothesis ; that nature is not to be dragged into our systems, nor restricted by our rules, and that, therefore, if we mean to investigate the truth, we must not dictate to her in a tone of autho rity, but mark her laws, observe her operations, and try to distinguish in what cases she principally employs her chemical, mechanical, and vital agents ? Perhaps she may even employ more than we have yet discovered : much is reserved for time and accident, and of much, too, we must for ever remain ignorant. To comprehend all that relates to the animal system, is to comprehend its great Creator, an attainment far beyond our hopes ; for though we can trace the chain of gradation from the meanest reptile up to man, from man to the Sovereign of the universe, the distance is unmeasurable.