Again, the human body is not made for the habitation of an infernal spirit, but for one of a quite different character. The boisterous passions of fury, discord and hatred ought never to disturb the mind, which is made for the habitation of endless peace and joy. The tumultuous passions are enemies to health; and this is so well known to physicians that they are very careful to prevent their patients from being any way ruffled or disturbed by violent passions. It is true these passions act upon the rational soul, which we may suppose to be distinct from that merely animal spirit, probably no other than the electric fluid, which runs along the nerves; but experience shows that each of these can act upon the other; a disorder in the body, particularly in the nervous system, will sometimes disturb the rational soul in such a manner as almost entirely to deprive it of all its faculties; while on the other hand a violent commotion in the rational soul may at once extinguish all the powers of life, as has already been shown from Zimmerman. Now, let any one consider what must be the sensations of those who engage in war. Whatever pity or humanity may be pretended, it is evident that in the day of battle all these sensations must give way to horror and fury on the part of the conquerors, and terror and dismay on that of the vanquished. That these passions never do entirely subside, is evident from the treatment of conquered countries and conquered people. When Jenghiz Khan beheaded his prisoners by hundreds of thousands, when Tamerlane pounded them in mortars, when Khouli Khan caused those who offended him to be carried from place to place, and a piece of flesh to be cut from their bodies at each stage, what must have been the sensations of these miscreants, and those whom they employed in such horrid scenes? On the other hand, what must be the sensations of those who see their dearest relations torn from them and slaughtered or treated even worse than if they were; themselves driven from their peaceable abodes to wander like beasts, while their cruel enemies exult in the miseries they have brought upon them, and glory in doing all the mischief they can, and spreading devastation as wide as possible? Thus, every passion, inimical to health, must, on both sides, be carried to its utmost height; and if these horrid scenes overspread a great part of the earth, for hundreds of years together, is it any wonder that plagues should ensue? If man, forgetting the dignity of his nature, converts the habitation assigned him by his Maker into a kind of hell, and himself into a devil, can we wonder that, in such circumstances, the spirit of life, originally appointed for his use, should become to such a being the spirit of death? Dr. Moseley seems to speak slightly of Helmont for assigning moral causes to fever; but if we consider the matter attentively it will certainly be found that the moral conduct of the human race in general has more connexion with the diseases which befal them, than we are perhaps willing to believe.
Most authors speak of some hidden, unknown and unsearchable power in the atmosphere as the occasion of plagues and other epidemics; and, from what has been already laid down, it seems by no means improbable that this hidden power resides in the electric part of it. But we know that electricity proceeds from the earth, as well as from the air; so that in some countries the evaporation of electric matter from the earth may affect the health of the inhabitants, as well as the constitution of the atmosphere. Hence some spots may be naturally unhealthy, and incurably so, independent of either the perceptible or imperceptible properties of the air; their healthiness may occasionally increase or decrease by means entirely beyond the reach of our investigation. Here then our inquiries must stop. We may indeed make a general conjecture that such differences are produced by the action of the electric matter; but, unless this action be pointed out, and some connexion traced between the situation of the country and a particular mode of action of the fluid, we may as well own our ignorance at once.
9. From all that has been said, then, we may conclude, that none of the obvious properties of the atmosphere, or of any constituent part of it, or of any variation in the proportion of its ingredients, can be accounted the cause of epidemic diseases; that the hidden constitution of the atmosphere may with probability be attributed to the agency of the electric fluid, and that by the action of this secret cause, along with the other more obvious properties of the air, such as heat or cold, moisture or dryness, &c. the human body may be so predisposed to diseases, that they will readily break forth; and that the conduct of mankind themselves may greatly contribute to this predisposition; the question then is, supposing every thing to be thus laid, like a train of gun-powder, what is the spark which first sets it on fire. Does the disease arise spontaneously in the first person affected by it, or does it come from without?
In answer to this we must in the first place observe, that the accounts of all plagues mentioned in profane history trace their progress from one place to another; whence the probability is, that at its origin the disease was confined to a few, perhaps to a single person. In very few cases, however, has it been possible to trace it to an individual; and, even when this has been done, the unfortunate individual is always said to come from some other place. The instance quoted from Dr. Moore is perhaps the only one upon record where the plague arose spontaneously in any person separated from society; and from a single instance little can be inferred. In those terrible examples we have given of people being burned to death without any accident from terrestrial fuel, the agent seems almost certainly to have been electricity. In the plague of Procopius, said not to have been infectious, the strokes complained of by many patients seem to indicate an action of the same fluid. The same in the plague at London, which was infectious, and likewise of others. But, in cases of plagues which are not infectious, another question arises—By what means do such diseases spread from place to place? for even this dreadful pestilence of Procopius did not overspread the earth at once, but is said to have begun at Pelusium in Egypt. To this no answer can be given. To suppose an omnipresent contagion in the atmosphere, proceeding either from contagion or any thing else, cannot be admitted; for upon this supposition the whole world must have been infected at once. The cause, whatever it was, plainly moved from one place to another, or was successively generated in different places. Recourse may be had to the precipitation of the contagious matter of former plagues from the atmosphere; but to account for this in succession will be found very difficult; and the same difficulty will attend every other solution which may be attempted. Mr. Gibbon indeed censures Procopius for supposing it not to have been infectious; and perhaps the spreading of the disease by infection is the only way by which we can account, in a satisfactory manner, for the way in which it diffused itself over the world, which was, by first infecting the maritime places, and afterwards those which were more inland; always visiting the second year those whom it had spared the first.
10. Lastly, to form some idea of the nature of contagion, or infection, as it is more properly called, we must consider, that as the ethereal fluid, acting as heat, pervades the human body, so doth it likewise under that particular modification which we call electricity. Some kinds of air, indeed most of those with which we are acquainted, seem to act by augmenting or diminishing the latent or the sensible heat of the body. Such, when taken in moderate quantity, may produce slight diseases, as head-ach, &c. and, when taken very largely, may even put an end to life at once, either by rarefaction of the blood and rupture of the small vessels, as is the case with fixed air, or by oppressing the lungs entirely with their basis, which cannot be thrown out by the breath as in ordinary respiration. Others may affect the electricity of it, or what in this treatise has been called the vital spirit, as well as the latent or sensible heat. The consequence of this will be diseases of a more serious nature; for upon this principle in all probability depend not only the secretion and proper regulation of the nervous fluid, but what has been called the crafts, or proper consistence of the blood and other fluids. Hence it is possible that such an instantaneous shock may be given to the body, as will not only injure the organization in an irreparable manner, but may be felt throughout the whole body like an electric stroke, even though there be no visible fire, or sensation of burning, as in the case of the Italian priest and others, who perished in such a miserable manner.
Formerly all acute diseases were supposed to depend on morbific matter taken into the body, and absorbed by the blood: the cure was thought to be accomplished by the expulsion of this morbific matter from the body by sweat, or some of the other natural evacuations. The doctrine was attended by many difficulties, and in many cases did not admit of a satisfactory explanation. It was therefore laid aside, and the debility or excitement of the nervous system arose in its place. But this new system admitting of miasmata and contagion, it was plain that morbific matter still kept its ground. With a view, it would seem, to render the nervous theory more complete, it has been found necessary to deny the doctrine of contagion and infection entirely. This has been done, wherever there was a possibility; but the phenomena of the small-pox and measles, as well as those arising from poisons, still militated strongly in favour of morbific matter. To avoid the force of arguments drawn from these sources, the doctrine of absorption was denied, and contagions of all kinds were said to act immediately upon the nervous system without affecting the blood or other fluids. At last the matter seemed to be decided by the experiments of the Abbe Fontana on poisons. He found that some proved fatal by being mixed with the blood, others by being applied to the nerves, and others by being taken into the stomach. Even this did not give satisfaction. It was contended that the effects of poisonous bites were too quick to be accounted for on the principle of absorption; that, after the most violent symptoms had commenced, they might be removed by cutting out the part affected; and consequently that, instead of any absorption by the blood, we were only to believe that the nervous system was irritated.
“Poisons, (says Dr. Girtanner) remedies, and, in general, all surrounding bodies, acting only on the irritable fibre, it follows that they act upon the system in a similar manner, and that every substance capable of producing the greatest possible effect upon the fibre, that is to say, every substance capable of exhausting all the irritability both of the fibre itself and of the system, in an instant, as for instance, laurel water, or white arsenic, is also capable of producing all the inferior degrees of action, either by acting on a fibre less irritable, or by acting upon the same fibre, but in a less quantity. Laurel water, opium, white arsenic, ammoniac, are of course both medicines and poisons capable of healing, as well as of producing, all maladies whatsoever, without exception.[93] And this is confirmed by a number of experiments which I have made upon different animals. This truth seems to me of the utmost importance; and the Abbe Fontana, who made more than six hundred experiments to prove that ammoniac is no remedy against the bite of a viper, would have saved himself the trouble, had he known it. If, instead of applying the venom of the viper to so many animals, and afterwards applying ammoniac to the wound, he had made a single comparative experiment, and applied ammoniac to a wound made by a lancet that was not poisoned, he would have found that ammoniac itself, applied in this manner, would have produced a disease exactly analogous to that caused by the venom of the viper; and, consequently, so far from removing the malady, must necessarily increase it, by exhausting the irritability of the fibre in a much less time than the venom of the viper by itself was capable of doing. Mr. Fontana has made more than six thousand experiments upon the poison of the viper; he employed more than three thousand vipers, and caused to be bit more than four thousand animals; and the conclusion he drew after this truly enormous number of observations was, that the poison of the viper kills all animals, and produces the disease by its action on the blood. But why did Mr. Fontana neglect to make the decisive experiment, the experimentum crucis of Bacon? It is well known that frogs, and many animals with cold blood, live a long time without the heart, and entirely deprived of blood. If therefore the poison of the viper kills animals by its action on the blood, it will not destroy frogs without blood. But experiment contradicts this reasoning. The poison of the viper will kill frogs without blood in as short a time as it kills those animals who have not lost their blood. It is not therefore by its action upon the blood that the venom of the viper destroys animals; and thus does it happen that a single experiment frequently overturns all that six thousand other experiments have apparently established. According to my experiments, poisons operate upon the blood just as they do upon the muscular fibre, by depriving it of its principle of irritability, or of its oxygen. After having made this observation upon the experiments of Mr. Fontana, I must do him the justice to add, that I have found all his experiments very accurate, and that in all those which I have repeated, the result has been exactly conformable to the account given by him; it is in his conclusion only that he appears to be deceived.”
On this I must in the first place observe, that since philosophers and truth seem to be so far distant from each other that even six thousand experiments cannot bring them together, it were greatly to be wished that in their researches they would pay a little more regard to humanity. If the Author of Nature has set man at the head of the creation, if inferior animals must patiently resign their lives to preserve ours, are we therefore authorised to torment and put them to death by thousands for every idle whim that comes into our heads? After Spallanzani, Fontana, Girtanner and a multitude of other learned barbarians had cut in pieces, boiled alive, poisoned and tortured thousands of inoffensive animals, new massacres it seems must be made, and new tortures inflicted, because an experimentum crucis is still wanted! If knowledge is to be obtained only by such means as these, it certainly must be derived from a very polluted source.
2. The experiment on which Dr. Girtanner builds so much is far from being above suspicion. Though we may cut the heart out of an animal, and let it bleed as freely as possible, yet we certainly overrate our abilities if we say that all the blood is taken out of it. The more perfectly an animal is bled, the less irritability it has; which gives a reasonable suspicion, that, if all the blood could be taken away, the irritability would cease entirely. In frogs, and all other cold blooded animals, the blood contains fewer red globules than in such as are warmer; the circulation is more languid than in such as have warm blood, and, of consequence, the blood will retain its irritability for a longer time, and it will likewise be more difficult to deprive the body of all its blood. In making this experiment, therefore, Dr. Girtanner ought to have brought unexceptionable proofs that he had deprived the frog of all the blood it contained. But, as this was not done, we shall be ready to suspect that some was left; in which case we should be still as uncertain as before whether the poison acted on the irritable fibre, or on the blood. But the decisive experiment, or experimentum crucis, seems to have been made by Fontana himself, by injecting a little of the diluted poison of the ticunas into the jugular vein of a rabbit. Here the poison was applied to the blood itself. It could get at no other part of the fibre but the inside of the vein, which is not accounted very irritable; and the quantity injected was so small, that the Abbe thought his experiment had failed; yet the animal died as if by lightning. The moment he turned his eyes towards it, it was absolutely dead, without discovering the least convulsive agony, or other sign of some little life remaining, generally observable for some time in animals killed by the common methods. On applying the same poison to a large nerve of another animal of the same species, no injury followed.
3. The dispute is of no consequence, and the experiment will prove the same thing whether we suppose the poison to act upon the irritable fibre (the nerves and muscles) or upon the blood. The only important point to be ascertained is, whether there be in nature any substance which, applied to the internal parts of the body, or to a wound, will instantly disorder the whole in such a manner as to bring on a violent disease which may prove mortal in a short time. If any such there is, that substance, whether solid or fluid, visible or invisible, may with propriety be called contagion; and if any such proceeds from the body of a diseased person to one in health, the vapour so proceeding is infection. As to the mode of its operation we are little concerned; the sudden manner in which people are affected shows that poisons kill by suppressing in a very short time the principle of life, which seems to be analogous to electricity, or rather the very same with it; neither is it more incredible that the poison of a serpent should kill by disturbing the natural electricity of the body, than that the stroke of a torpedo, or electrical eel, should kill by the same means. The only difference is, that, in the case of poisons, the pernicious substance is introduced into the body itself; in the torpedo, it comes with violence from without. The former we may compare to the silent discharge of an electrified jar by a point, the latter to its discharge with a violent flash by a knob. But that in poisonous bites the blood is greatly affected, and that in a very short time, we certainly know. There are some kinds of serpents whose bites are so suddenly fatal, that no cure can be applied: one of these, called the small laharra, is mentioned by Mr. Bancroft in his Natural History of Guiana. Mr. D’Opsonville, in his Philosophic Essays, takes notice of one in the East-Indies, which he calls the poison serpent or serpent poison, which seems to be as bad as the laharra mentioned by Bancroft. This too is but small, viz. two feet long, and very slender. Its skin is freckled with “little traits of brown, or a pale red, and contrasted with a ground of dirty yellow: it is mostly found in dry and rocky places, and its bite proves mortal in less than one or two minutes. In the year 1759, and in the province of Cadapet, I saw several instances of it; and, among others, one very singular, in the midst of a corps of troops, commanded by M. de Bussy. An Indian Gentoo merchant perceived a Mahometan soldier of his acquaintance going to kill one of these reptiles, which he had found sleeping under his packet. The Gentoo flew to beg its life, protesting that it would do no hurt if it was not first provoked; passing at the same time his hand under its belly, to carry it out of the camp; when suddenly it twisted round, and bit his little finger; upon which this unfortunate martyr of a fanatic charity gave a shriek, took a few steps, and fell down insensible. They flew to his assistance, applied the serpent-stone, fire, and scarifications, but they were all ineffectual; his blood was already coagulated.[94] About an hour after I saw the body as they were going to burn it, and I thought I perceived some indications of a complete dissolution of the blood.”