Part 16

XXVI. Who judging by general or common principles, would not conclude, that wet hay was much less liable to take fire than dry? But experience teaches us, that by putting together quantities of hay too moist, it will take fire of itself, which could never have happened, if the hay had been put together sufficiently dry, or more thoroughly made.

XXVII. What maxim is better established, or more generally assented to among the naturalists, than that a vivifying heat of the blood, is indispensably necessary for the preservation of life? But with all this, Father Plumier, a learned priest of the order of Minimus, in a voyage in the Pacific ocean, for want of water, found himself under a necessity of drinking the blood of turtles, and declares, he found it as cold as the common water in Europe. (Mem. de Trevoux, an. 1704, tom. 1. page 175.) Who, agreeable to the laws of ratiocination, can say otherwise, than that the third quality, resulting from the mixing three or four fœtid things together, must be fœtid also? But experience manifests to us, that this consequence is not infallible. Mr. Lemeri bought a certain quantity of the gums galbanum, sagapenum, and opopanax, and also some bitumen of Judæa, which he put all together into a retort, and found that there resulted from the mixtures, a strongly scented oil, greatly resembling musk; now the bitumen in smell, does not in the least resemble musk, and the other three drugs are absolutely fœtid. (Hist. de l’Academ. Royal, ann. 1706.)

XXVIII. If a philosopher, destitute of all other information, except that which he had acquired in the schools, should be told that two liquids, which to the touch appear cold, should upon being mixed together, not only heat and boil, but also emit a flame; he would be in a terrible agitation, and armed with his infallible conclusive principle, _that nothing can communicate a quality which it does not possess_, would exclaim against the proposition. But let him exclaim as much as he will, it is a certain fact, that from mixing a pure acid, with the essential oil of an aromatic plant, there will result that commotion.

XXIX. We know that water, is much heavier than air; and we also know, that the vapours which arise from the earth, are nothing else but particles of water, very minutely divided, and consequently, that they must be much heavier than particles of air of the same size. We know also, that a liquid cannot ascend above another, when they are put together, except when it’s particles of equal size are lighter than those of the other. From these premises, it should follow as an infallible consequence, that these vapours cannot rise superior to the air we breathe. But let this consequence appear ever so infallible, experience convinces us that the fact is otherwise.

XXX. Nobody is ignorant, that the aromatic species, such as the clove, the pimienta, and the cinnamon, are hot or heating, and that the regions nearest the poles are cold, and those nearest the equinoctial hot. From these premises, what naturalist would not infer, that the use of these species would be less pernicious to the inhabitants of the cold regions, than to those of the hot? But experience is ever demonstrating to us the contrary. For a scruple of clove is more offensive to, and has a greater effect on the first, than a drachm has on the last.

XXXI. And similar to this, has been the experience of the Hollanders, in some of their voyages to the East Indies. It happened once, that upon passing the line, the greatest part of the people belonging to a ship were taken sick, and that more than half of them died, and that those only recovered, to whom in their sickness they gave great quantities of brandy. The medical men found great difficulty in believing, that these people could owe the preservation of their lives to drinking to excess of a liquor, which if not taken sparingly and with moderation, is found to be very pernicious to health. But in the end, they found themselves obliged to yield to experience; and admit of the liberal use of brandy, which afterwards delivered with equal success, all the afflicted from their illness.

XXXII. It is then absolutely necessary to submit to experience, and if we are not disposed to abandon the real road of truth, to seek for nature in herself, and not in the deceitful image which our fancy forms of her.

SECT. VIII.

XXXIII. I am not ignorant that there are some schoolmen, who represent the application to experiments, as disgraceful to, and beneath the dignity of philosophy. But this is a most absurd error, for at this rate, studying the imaginations of men, would be a more honourable occupation, than ruminating on the works of God. In books of theory, we contemplate human ideas; in natural entities, divine ones. Let reason now determine, which is the most noble study.

XXXIV. The prince of philosophers, Aristotle, thought differently in this respect to the present school ones, for he said, we should not disdain to examine with our senses, the most trifling works of nature, for that we should find in them all, marks of sublime wisdom, and just and beautiful ingenuity: _Aggredi enim quæque sine ullo pudore debemus, cum in omnibus naturæ numen, et honesium, pulchrumque insit ingenium._ For so it is, that in the most humble plant, in the most vile insect, and in the most rude rock, we see the traces of an omnipotent hand, and the marks of infinite wisdom.

XXXV. Besides this, it is a matter of great importance to him who is in search of truth, to chuse the path that leads directly on to his object, and not to pursue that which will conduct him out of his way, although it should to the eye, appear the most desirable, and the most pleasant to walk through. There is no doubt, that a physician in a college, mounted in a professional chair, and reading a lecture, makes a more pompous figure, than when he is attending to, and observing the dissection of a dead body in an hospital; but it is by attending to the dissection, that he attains a knowledge of the situation and arrangement of the internal parts of the body, which he could never have acquired, by reasoning or disputing all his life long in a school. Ideal gold, is possessed in imagination by lazy people, who while they are sleeping in their beds, dream it is showered down on them; but the true ore, can only be acquired by force of labour, and digging in the mines with diligence and industry. And in no other manner, otherwise than in appearance only, can we attain more, than that shadow of truth, which we call probability, for these are the largest advances we can make, by the force of our imaginations exerted in the retirements of the closet; and the truth itself, is only to be found by scrutinizing sensible objects, and searching in them, for the hidden secrets of nature.

SECT. IX.

XXXVI. There is another objection to experimental observations, which is not more reasonable, or better founded than that we have just mentioned, which is made by some superficial schoolmen, who say, that these sort of enquiries, do not require reason and perspicuity, but only eye-sight, diligence, and memory; on which account they condemn them, as things not well calculated for the exertion of invention, and ingenuity. But how little do these people know of the nature of those physical experiments, or of the manner in which they are made, which have employed the attention of so many learned and sublime spirits, of France, Italy, England, and Germany. In order to discover whether any deceitful appearance has crept in, they repeat every experiment many times over; and invent many ingenious methods of examination, to find out, whether the phenomenon proceeded from that cause, which at first sight it seemed to be derived from, or whether it was the effect of some accidental, or occult one. They make exact and nice combinations of their experiments, and invent ingenious methods of comparing them one with another, and then weigh in a most delicate balance, both the analogies, and the differences between them, in order to derive with almost mathematical certainty, the consequences to be deduced from them; and they peep into those crevices of nature that are nearly imperceptible, that they may discern through them, her inmost secrets; and I beyond comparison, find more delicate ingenuity, and more perspicuity, in many of the experiments of the famous Boyle, than I do in all the abstractions, and reduplications, of the most subtle metaphysicians.

SECT. X.

XXXVII. It is certainly and indispensably necessary, to make experimental observations with the most exquisite attention, in order to avoid our being deceived by them, as our forefathers have been, and as many people are at this day; who, confiding in a superficial and careless experiment, have precipitated their conclusions, and without giving themselves time to reflect, have deduced consequences, from the first information of their senses. From the ascent of the water in the pump, by considering the thing inattentively, was inferred the repugnance of nature to a vacuum. To what labours did Torrizeli, Pascal, and other sublime geniuses submit, what a variety of experiments did they make, and with what ingenuity did they combine and compare them, in order to undeceive the world, and convince mankind, that the true cause of this phenomenon was the weight of the air!

XXXVIII. From the flame flying upwards, was inferred the chimerical region of fire, immediately adjoining to the heaven of the moon. In our essay on Physical Paradoxes, we related the ingenious experiment with which my Lord Bacon proved, that the flame did not ascend from any natural propensity it had to fly upwards, but because it was compelled to it, by the lateral pressure of the air.

XXXIX. I was once in conversation with some school philosophers, and our discourse happening to turn upon physical matters, I took occasion to propose a question to them, which was, whether cold water (and the same may be said of every other liquid) was more subtil and penetrating than hot, which it seemed evidently to be, by the following experiment, that when we poured iced water to drink in summer time into a glass, we perceived the glass wet and moist on the outside, which had the appearance of the water having transuded through the pores of the glass; and as this did not happen when the water was luke warm, or in a temperate state, it was inferred that such water, was not so subtil and thin as cold. As the bystanders seemed converts to the force of the before-named experiment, it gave me a good deal of trouble, to undeceive and convince them of their mistake, although at length I accomplished doing it, by making it evident to them by various most clear experiments, that the moisture which adhered to the outside of the glass, did not transude through its pores, but that it consisted of the coagulated vapours, of the circumambient air, which being in a warm state, condensed and were converted into water, upon their coming in contact with any very cold body, and that they became more condensed the less porous this body was. For this reason, the vapours that are raised by fire, condense as soon as they come to the head of the alembick; and for the same, if we breathe upon a bright iron bar, or any other metallic body, that has a smooth or polished surface, and is very cold, the vapour we breathe from our mouths, when it comes in contact with that body, will condense, and adhere to it; and it is also for the same reason, that in frosty nights, we see the inside of the glass of windows moist, when they are dry without, which appearance, I have known surprise many people, who thought that that humidity was a portion of the external air, which had penetrated through the glass; and it is likewise for the same reason, that our breath, and the breath of other animals, is visible in cold weather, it being then sufficiently condensed by the circumambient air, to make it become apparent. But the most convincing argument I made use of in the dispute, and which I advanced as a conclusive one, was, that if you covered the exterior superficies of the glass with paper, there would not the least moisture adhere to it, in the whole course of a frosty night, and it is clear that the paper is not impenetrable to moisture, but can only prevent the external air, from coming immediately in contact with the glass.

XL. As it relates to the subject of the impenetrability of glass by liquids, I cannot forbear in this place taking notice of another very common error, which has originated from drawing conclusions hastily from experiments, without making proper reflexions on them. It is generally believed, that the zest of the rind of a lemon penetrates through glass, which opinion is founded on the persuasion, that if you press out the zest on the outside of a glass, the liquor that is within will taste of it. I concluding this penetration to be impossible, after meditating upon the matter, easily discovered the cause of this error; which is as follows, upon pressing out the zest, some of the particles are apt to fly and rest on the edges of the glass or very near it, and adhere to that part, which in drinking the lip is applied to; and thus the palate perceives the taste of the zest, which is communicated to it, from the edge of the glass. To determine whether this was not the case, I squeezed some of the zest in the ordinary way against the outside of the glass, and then turning it half round, applied my lips to the opposite side, and did not perceive the least taste or flavour of the zest of the lemon. And it will happen the same to any one, who will give himself the trouble to make the same experiment.

SECT. XI.

XLI. The evidence of our senses alone, then, is not sufficient to enable us to derive just conclusions from experiments; for caution, reflection, judgement, and reason, are always necessary; and sometimes in so great a degree, that all the exertion of human talents and ingenuity, is not equal to an adequate examination of the phenomena. Sir Isaac Newton, an Englishman, who was a genius of the first rate, and a member of the Royal Society of London, in the beginning of the present century, published various tracts upon optics, in which, he displayed a great novelty to the philosophers and mathematicians; that is, that all colours exist and are contained, actually and formally, in the rays of light; which are constituted of heterogeneous particles, of unequal refrangibility. He proved this singular opinion, with many experiments of exquisite invention, contrived and considered, with no less exquisite delicacy, and in fact, made more than a few converts to his opinion in many parts, but more especially among the English mathematicians; and a Mr. Gauger who was one of these, enforced the Newtonian doctrine, with a great number of additional experiments; but in a short time, one Senor Rizetti, wrote against this new system, and stated many experiments in favour of the old opinion, and even pretended, that those which had been quoted by Gauger, militated against the Newtonian sentiment. Gauger replied to this, and paid Rizetti in his own coin; that is, he not only defended the consequences which he deduced from his own experiments, but turned those derived from the experiments of Rizetti against the doctrine of the Italian. It is certain that experience, as applied to many objects, opens a most extensive and fertile field for exercising the ingenuity of man, and that nature, even to him who seeks to know her in that way, is in various instances impenetrable and inaccessible.

XLII. But we should acknowledge that in general, the difficulties are not so invincible, as not to be surmounted by reason and industry, and that the deceptions which sometimes result from experiments, proceed either from the want of proper diligence and attention in making them, or from the want of adequate ingenuity, to judge of, and decide upon them.

XLIII. This is very frequently the case with respect to medicinal observations; and from hence springs that enormous disagreement, with respect to the opinions that are alledged to be founded upon them. One says, that he has experienced the efficacy and salutary fruits, of such a medicine, in such a disease; and another insists, that he has administered the same medicine, in the same disease, and under the same circumstances, and found it to be pernicious. One of the two must be mistaken, and I believe it is not very uncommon for both of them to be so; for it might possibly happen, that the medicine neither did good nor harm, and that the administration of it, was a mere matter of indifference, and the thing itself what we call a chip in porridge. But from what could this difference of sentiment and assertion arise? Why from one of them seeing that his patient, after administering the medicine to him grew better, and from the other perceiving, that his after taking it grew worse; although it might possibly happen, that neither the one grew better, nor the other grew worse in consequence of taking the medicine, but from a very different cause. The diseases of the two patients, from their different constitutions, or internal temperaments, (which is for the most part, a thing impenetrable to physicians) might be in such a state, that the one was disposed to abate, and the other to increase.

XLIV. And although the patients may be numerous, with respect to whom this experience is alledged; and admitting that they neither all die, nor all recover, every one according to his pre-occupation, will impute to the remedy, either the happiness of those who did well, or the misfortune of those who perished; and unless they shall resolve, to make a computation of the good or bad success of the practice of those who use that medicine, with that of those who never administer it, and compare them carefully together, this doubt will probably never be cleared up.

SECT. XII.

XLV. This inattention, is without doubt what produces, and what keeps up in the world, men’s estimation for an infinite number of useless things, on which they bestow the noble epithet of remedies; and this false notion, has filled the medical books and the apothecaries shops, with an infinite deal of trash, the reading of which fatigues the memory; and the taking of which, ruins the health and constitution of the patient. You will find accumulated in them, a great number of remedies for slight diseases, which if left to nature, would cure themselves; and although all practitioners do not approve of the same remedy for the same disorder; does this prove, that the patient of each got better by taking this or that thing? I say does this prove it? for neither the imprudent sick person, nor those about him, hardly ever reflect, that there were many others besides him, who were affected with the same disorder, and who without taking any medicine at all, recovered as well, and as quickly as he did?

XLVI. A benign or favourable sort of catarrh, as is very frequently the case, becomes epidemical in a city; for which, some call-in the doctor and take medicines, and others do not; and such is the blindness of those who have had advice as it is called, that they believe they owe the recovery of their health to the doctor, although they evidently see, that all those recovered as well as they, who had no advice, and who took no physic.

XLVII. The delicate fine lady, who whenever she feels a slight pain in her head, sends for the doctor, is fully persuaded, although the pain continues for the space of twenty or thirty days, that the capital pills he prescribed for her, removed it; but it does not occur to the poor lady, that many of her friends and neighbours, who at times have the same sort of pains in their heads, and who take nothing for them, get well as soon, and frequently sooner, than she with the help of all her pills.

XLVIII. It is very common for those who have pains in their teeth and jaws, (and I say the same of all those affections which come and go of themselves,) to fancy, and give the preference to a particular remedy, which they are of opinion relieved them; but it is proper to observe here, that every one applauds his own, and reprobates as insignificant, that which is used by other people. From whence does this arise? some will say, that as peoples temperaments are different, it may happen, that in the same species of complaint, the remedy which does good to one man, may have no effect on another; but this is a common and inefficient evasion, and such a one, as overturns and levels to the ground, the use of all medicinal applications; for if this was the case, as all individuals have distinct temperaments, no less than distinct faces, it would be necessary to contrive a distinct medicine for every single individual, and in all his disorders, to apply particular remedies, different from those, which in the same species of complaints, should be administered to every other person.

XLIX. The cause then of this opposition of sentiments, is most probably as follows. The first time a man is attacked with a pain in his teeth or jaws, it is very common for him to make use of various applications, for besides those which are ordered by the doctor, all those who have felt the same pain, recommend, some one thing, and some another; and as the sensation is acute, the poor patient anxious to be relieved, proceeds in succession, to apply all those remedies, at length, perhaps at the end of eight, ten, or fifteen days, the pain abates; and as there is not one of those days, in which the patient has not made use of one or other of these receipts, happy is that which he used the last; for to that he attributes his relief, and reprobates all the others as insignificant. Another diseased person, proceeds to take his medicines in regular order; but the course of this regulation, frequently depends upon the casual concurrence in opinion of the people who are consulted, or the power that one of them has of prevailing over, and leading the rest; from whence it frequently happens, that this man of persuasive eloquence, advises the using a medicine in the first instance, which some other practitioner might think it advisable to administer last. The result of which is, that in case the patient does well, his recovery is imputed to the application of the last remedy; and hence it comes to pass, that one reprobates a medicine which another applauds, and so _vice versa_. Thus all the reputation the remedy acquires, be it what it may, depends upon the casual application of it, just at the time nature was disposed to terminate the disorder by a favourable crisis, and hence it is, that the relief came to be attributed to the medicine. And notwithstanding that afterwards, upon another occasion, by using the same medicine in the first attacks of the same complaint, they did not experience the same effects from it; still the same prepossession is continued in its favour, that was formed on its supposed success on the first trial; and although the patient, did not find himself better for several days after taking it in this last instance, they persisted in imputing his recovery to the favourite receipt, and in thinking that without the assistance of it, the disease would have been more tedious, and more severe. Nor is it of any avail to remove this prejudice, their seeing that others, who neither make use of that or any other remedy, do not suffer more prolix, or more acute pain than those who apply it; for although they see they will not perceive it; and if they do perceive it, they will not attend to or acknowledge it.

SECT. XIII.