SECT. I.
I. There arrived in the kingdom of Cosmosia, two famous women, who were very opposite to each other; but both with the same design, which was that of obtaining the absolute dominion over that empire. The first was called Solidina, the other Idearia; the first was learned, but simple; the second ignorant, and ostentatious. The people of the country, were ignorant like the last, and simple as the first. Hence, Solidina thought to win them to her by kindness, and by instructing them; and Idearia, to subdue them by craft and imposition. Idearia opened a public school, and promised in pompous language, that in a very short time, and with little or no trouble, she would make all those extremely learned and wise, who chose to attend her lectures. The greatness of the promise, joined to the imposing appearance of the new doctress, mounted in the professional chair, together with her great volubility, and flow of mountebank rhetoric, soon filled the school with pupils. She began her lectures, which all consisted, in laying before her auditors in new and unusual language, the chimeras, contained in the extensive field of the imagination. And, oh wonderful to relate! either Idearia had somewhat of enchantment about her, or else there was something very singular in her method of applying her artifice and cunning; for in a few years after opening her school, she persuaded those miserable people, they perfectly understood all that could be learned.
II. Solidina, pursued a course diametrically opposite to that taken by Idearia. In an humble garb, and without any parade or ostentation, she went from house to house, and familiarizing herself with all men, taught them in plain and easy language, true and useful documents. The most retired cottages, and the most humble work-shops, were schools suited to her doctrines, for she found in all of them, sensible objects, which examined by the help, or auxiliary aid of the understanding, served the purpose of books for teaching and explaining her lessons; and so far was she from inspiring an indiscreet presumption in her disciples, that she ingenuously told them, that all she taught, was a mere trifle, compared to the infinite deal there is to be learned; and that to arrive at a moderate knowledge of things, required infinite labour and application. This modesty of Solidina’s, was very prejudicial to her, because at the very time she made this declaration, Idearia, was boasting and blazoning in her school, that in a concise mode, and with very little trouble, she would make all her auditors universally learned; the consequence of which was, that the pupils of Solidina one after another began to drop off, and go over to Idearia, in hopes that in her school, they should arrive at the summit of learning per saltum. What contributed much to forward this defection, was, that Idearia also spoke of Solidina with contempt, calling her base, vile, mechanical, and stupid; by which means, the poor tutress became abandoned by all the people of rank, and was obliged to retire from the city to the villages, where she applied herself to instructing poor husbandmen, in that sort of knowledge, that was necessary and useful, for the cultivation and improvement of their lands.
III. Idearia by the banishment of her rival, now becoming triumphant, entertained thoughts of establishing an absolute and despotic sway over her disciples; and to accomplish this purpose, she published an edict, by which every one was required not to believe in future, aught he should see with his eyes, or touch with his hands, but only to credit such things as she should be pleased to order him to believe; requiring further, that he should look upon it as an indispensable obligation, always to defend with invincible obstinacy and unremitting vociferation her doctrines, against whoever should presume to contradict them. All heads bowed obedient to this tyrannic decree, and people began firmly to believe many maxims, which before they had found a difficulty in assenting to; such for example, as that the truth can never be found out or ascertained but by means of fiction; that there is a mode of coming at the knowledge of things, which may be taught to a child in four days; that mankind are all alike, which is a rule that will hold good with respect to every other species, and if you know what one of a sort is, you know what they all are; that insensible and inanimate things, have their desires, their prejudices, and their affections, the same as animate ones; that that body, which is the most brilliant, and most heating of any, has nothing igneous in its composition; and that on the other hand, there is another very large body, which is purely igneous, that is neither luminous, nor heating, nor does it stand in need of any pabulum to sustain it; that all living creatures have a large portion of fire in their composition, without excepting even the fish, although they are always in or under the water, nor the turtle, whose blood is positively cold.
IV. These and many other such-like portentous particulars, did Idearia teach to, and impose on her credulous disciples; who all received and embraced them as infallible truths; but at length there arose in the very school of the doctress herself, a contentious schism, or scandalous disagreement, which was begun by one Papyratius, a man of subtil and animated genius, but a great lover of novelties. This man introduced new and not less astonishing dogmas than the others; such as that all the living creatures in the world, man only excepted, have no more sensation or feeling than stocks or stones; and that in every man, there is but a very small portion of the body which possesses the presence of the soul; that the extension of the world is infinite; that the motion of sublunary bodies, is equally semper-eternal with that of the cœlestial ones; that the imaginary space, is really and truly a body; that every thing upon the face of the earth, is in so continual and rapid a motion, as in the space of every twenty-four hours, to travel some thousands of leagues; that we in all things, should give credit to our imaginations, but none to our senses; for that the representations made by these last, are apt grossly to deceive us; and that neither is the swan white, or the crow black, nor is fire hot, or snow cold, &c.
V. These novelties, and others of the same sort, although they were condemned from the beginning by the majority of Idearia’s disciples, did not fail to attract a number of votaries, sufficient to form a new school. The two parties inveighed against each other with great bitterness, and one side reprobated as absurd errors, what the other maintained as conclusive dogmas.
VI. This division, after long and obstinate disputes, in which the arguments were so nearly poised in equilibrium, that neither side could claim the victory, in the course of time, opened the eyes of many, and made them doubt whether they had not lightly, or even blindly, admitted as articles of human faith, doctrines, that were uncertain, and exposed to be terribly contested. They observed, that the arguments with which each side attacked the opinions of their opponents, were beyond comparison stronger, than the reasons with which they defended their own. From hence they inferred, that both the one and the other were evidently doubtful, and might very probably be false. This brought to their remembrance the poor and neglected Solidina, and made them reflect, that she proved all she advanced, by sensible and plain demonstrations. This remark becoming every day more general, and more adverted to by men of the first-rate ingenuity in the schools; they took the matter into consideration, and the result of their deliberations was, a determination to recall Solidina from her retirement, and to bring her back to the city; which after having done with solemn pomp, they erected a magnificent school for her, where she has continued to teach from that time, with a reputation that has increased daily; and her being favoured with the countenance and protection of some illustrious personages of high rank, has greatly contributed to advance her credit, and particularly the encouragement she has met with from the princes, Galindo and Anglosio, who are both great lovers, and patrons of Solidina.
SECT. II.
VII. This History, which was printed in French, was given me to read by a stranger who was on his travels; but as soon as I had read what I have just related, he snatched the book out of my hands, and asked me if I comprehended what I had read? The question gave me to understand, there was something mysterious in the History, and that under the plain letter, was conveyed some signification, different from what the words expressed. I answered him, that I had not understood it in any other sense, than what the language seemed to imply; but that if he would permit me to read it over again with a little attention, I might perhaps be able to comprehend its meaning. He gave me leave, and then upon reflection, first on the nature of the doctrines it mentioned, although they were not pointed out very clearly, and secondly, on the allusion of the names given to the personages who were introduced into the scene, I found it was not very difficult to decypher the riddle, which I interpreted in the following manner.
VIII. The kingdom of Cosmosia is the world, which is the signification of the Greek word Cosmos. Solidina is experience, and Idearia imagination. These names are very properly suited, both to the characters and doctrines of the parties. Experience solidly proves her maxims, by sensible and clear demonstrations; and imagination, grounds her opinions on the vain representation of her ideas. Solidina was a long while banished, and during all that time, Idearia reigned triumphant; for from the period that Pythagoras reduced all philosophy to his numbers, Plato to his ideas, and Aristotle to his precisions; and for many ages afterwards, the world knew no other but an ideal physic; nor did it pay the least attention, to the experimental or solid. In the first maxims of Idearia, we perceive many of the dogmas of the peripatetic doctrine, and in her second, many of the Cartesian ones; and they gave the name of Papyratius to the broacher of this last system, because the French word Carte, signifies the same as the Latin word Papyrus, from whence the appellative was derived. Des Cartes is ranged among the auditors of Idearia, because he was disposed instead of less, rather more than the Peripatetics, to regulate all physics by imagination and ideas. At length the mistake of this method was perceived, and Solidina was recalled from the villages to the city; and experiment and observation, which for a long time had only been in use among the rustics, and employed in the business of husbandry, to increase the product of the earth, improve the mountainous land, and to encourage the propagation, and mend the breed of herds and cattle; were not long since introduced in pomp, and countenanced by some courts, in the neighbourhood of which, academies were instituted, to examine nature by their help; and as the most celebrated of these, were the Academy of Sciences at Paris, and the Royal Society of London, which were founded under the protection of the kings of France and England, they called the two princes who were the lovers and patrons of Solidina, by the names of Galindo, and Anglosio, which were derived from the Latin words Gallia, and Anglia, which in that language signify France and England.
IX. The stranger approved of the whole, and every part of my explanation, and assured me, that by the context that followed what I had read, the intention of the author of that mysterious History, could be no other than what I had described it. But I told him I was not inclined to approve, nor could I approve of the whole and every part of its content; for that I observed in it some latitudinary expressions, which seemed to reflect upon, and were derogatory of the peripatetic doctrine, so I only acknowledged to him, that in the most essential parts, the thing seemed just and right. He replied, that as I was a Spaniard, and a sectary of the peripatetic school, my objection and the reasons for it might be admitted. Upon saying this, he took his leave of me, and pursued his journey, leaving me in a disposition to meditate on the subject of our conversation, and lay before the public, such reflections as should occur to me respecting the matter of it, which may be seen in the sequel of this discourse.
SECT. III.
X. The first thing that offers itself to our consideration, is the little or no progress, which natural reason, unassisted by experience, has made in the examination of the affairs of nature in the course of so many ages. Nature is as little understood in the schools at this day, as it was in the academies of Plato, of Lyceus, and of Aristotle. What secret have these academies developed? or what diminutive portion of this most extensive country have they discovered? What utility has the labours of so many men of excellent ingenuity, as have cultivated philosophy in the reasoning and speculative way, produced to the world? What art, either liberal or mechanical, of the many that are necessary for the service of man, or the good of the public, do we owe to speculative invention; and I might even say, what small advancement in any such art, has been derived from it? What document of the schools, has conduced to instruct a husbandman in the cultivation of his lands? They there talk much of causes, effects, productions, and dispositions of matter, but all this has not yet produced any maxim that can be relied on, for the most advantageous mode of cultivating the land, in order to dispose it to the production of this or that particular plant, nor to instruct us at what time it should be sown, nor in the least to inform us with regard to many other circumstances, that should be attended to in the raising it. Schoolmen, after the example of Aristotle, treat largely of qualities, which they place in a predicament apart, or by themselves; without having by this means, discovered any qualities at all, either in the mixtures, or the elements; but on the contrary, Aristotle has rather been miserably mistaken in those he attempted to point out, by his rules of proportion and combination; I mean in those that appertain to the air, and the water, as we have proved in another part of our works; and it would not be difficult to prove the same thing, with regard to those he has assigned to the earth. If perchance he has been right in ascertaining the qualities belonging to fire, (although in our Physical Paradoxes we have denied his position with respect to its being hot in the highest degree) I say, if he has been right in this particular, it was not because philosophy had penetrated the secret, but because the thing was manifested to us by our senses.
XI. These are the organs, by which all the natural truths we are able to obtain a knowledge of are conveyed to our spirits. Even in the mathematical faculties, which affect to confide every thing to theoretical demonstrations, they cannot, except in the two elemental ones, arithmetic and geometry, safely advance a step, without holding before them, the light of experience. It was this taught the geographer, the situation and position of the divers parts of the globe; the navigator, the directive virtue of the load-stone; the static philosopher, the weight, the descent, and acceleration of motion in their descent, of heavy bodies; the mechanic and engineer, the augmentation of power by machinery, or the multiplication of purchase; the astronomer, the movements and course of the stars; the musician, the consonant and dissonant intervals of music; the optician, perspective, or the effects of vision when the eye surveys distant objects; to the catoptrician, and dioptrician, the laws of reflexion, and refraction.
SECT. IV.
XII. And it is very worthy of remarking, that even after experience had made those first discoveries, on which the theory and practice of arts are founded, those primitive lights were in general found to be insufficient to enable the understanding to make further advances in them, but it was rather found to be necessary, that the same experience should continue as they proceeded on, to direct their steps, and correct their errors. I will explain what I mean, by two examples taken from navigation.
XIII. The first regards the direction, or pointing of the magnetical needle to the pole. This admirable property, which was totally unknown to the antients, was discovered in the thirteenth century, and immediately applied to the improvement of navigation. Upon its first discovery, the philosophers, according to their wonted custom of pretending to discern the causes of things, imputed this effect, as derived from an occult sympathy with the pole, contained in the very essence, form, and substance of the loadstone; and as this is supposed to be invariable, they concluded, that the direction must infallibly be invariable also. They continued in this good faith for about four hundred years, at the end of which long period, Crinon, a pilot of Dieppe as some say, or Cabot, a Venetian Navigator as others believe, was the first who observed the declinations of the magnetical needle from the true north, that is, that it did not always point directly to the pole, but declined in different places, sometimes towards the west, and at others towards the east. The philosophers heard this novelty with great disgust, because it gave the lye to some of their most established maxims, and therefore they set about to contradict it with all their force. But in the end, they were obliged to submit to repeated experiments, authorized and confirmed, by the testimonies of people of undoubted credit.
XIV. Having afterwards discovered, that under the meridian of the Azores or western islands, there was no variation of the magnetical needle at all, the astronomers and geographers, thought they had found out a fixed station, whereat to commence the first meridian, which had before been counted arbitrarily, from whatever place they chose to begin it. But this idea soon vanished, for a little while afterwards, they discovered two other meridians, where there was no variation; the one at a head-land near the Cape of Good Hope, to which, on this account they gave the name of Needle Cape; and another, at the spot where the city of Canton is situated. Upon this, they thought they had found out a certain principle, whereon to ground a compleat system for calculating or computing variations, by graduating them for the intermediate stations, in proportion to their greater or less distance from the mean space between the two places where there was no variation.
XV. But as nature frequently mocks the ideal propositions that are fabricated by the brain of man, this time of rejoicing lasted but a few years, for they discovered, that this declination of the magnetic needle, varied more or less at the same place at different times, and that this change of variation was perpetual. This discovery, not only demolished the antecedent imagined rules, but nearly took away all hope, of their ever in future, finding out any certain one for their guidance; and this, notwithstanding many men, eminent for their skill in physics and mathematics, have long, and still do, labour at accomplishing it.
XVI. In this instance, may be seen the fallibility of the most plausible reasonings unaccompanied by experiments. And we shall see the same, in the other we are about to mention, which relates to the flux and reflux of the sea.
XVII. As the flux and reflux of the sea, is evident and apparent to all those who inhabit near the sea-coasts, and the course and changes of the Moon to all mankind, it was easy and natural, to observe the correspondence there was between the movements of the one and the other; that is, that the rising and falling of the tide, keeps pace with the rising and setting of the moon; and it is probable, that the first people who remarked this, fancied that by this single observation, they had discovered the system of these admirable movements. But this delusion was but short-lived, for they soon afterwards observed, that within the space of the same lunar month, there was a great disproportion between the rising and falling of the tide, and that it flowed higher, and ebbed lower, at the new and full moon, than it did at the quarters. But when they had advanced this step, it is likely they gave themselves credit for having discovered the whole secret, and supposed, that they knew all that was to be known of the matter; and when they observed there was so exact a correspondence, between the motions of the tide, and the phases of the moon, they did not entertain the least doubt, but that they were totally influenced by this planet. But experience also undeceived mankind with respect to this error, for they found out, that there was another variation of the tides, which did not depend upon the revolutions of the moon, but upon those of the sun; that is, that supposing other things to be equal, they rise higher, at, or near the equinoxes, than they do at the solstices. This gave them to understand, that the moon did not reign so despotic over the tides, as to exclude the sun from all share in the dominion of them.
XVIII. But after all this was ascertained, they found, that by trusting the bringing of ships into barr’d or tide harbours, to the mere combination of the before-nam’d observations, they fell into very dangerous errors; for that there are two other variations, which are very considerable, and especially one of them, and which can’t be comprehended under any general rule whatsoever; the one is with respect to the time of full sea; and the other, regards the quantum of rise of the water. The time of full sea varies at different ports, even under the same meridian, and does not happen in all of them at the same hour. They vary also with respect to the magnitude of them, because there is an enormous difference in the height they flow at some ports, to what they do at others, for the water will rise more than ten fathoms upon some coasts, and not above a few feet on others, and in others again, the rise is hardly perceptible.
SECT. V.
XIX. If the rules deduced from experimental observations are so fallible, that it is absolutely necessary in order to avoid all error, to pursue the thread of them so scrupulously, that reason should not venture to advance a step, without the light of an experiment appropriated to the business it is in search of; I say, if these rules are not to be relied on, what confidence can we place in those maxims, which derive their origin from our arbitrary ideas?
XX. Nature conforms to, and is governed by the idea of its great artificer, not by that of man; and it is strange temerity in man, to presume he can comprehend the idea of such an artificer. I have sometimes thought, that if we were told, that there were numbers of those luminous bodies in the heavens which we call stars, although we could not see them, every one would imagine, such a disposition and collocation of them in the sphere, as best suited his own fancy. One would conceive them distributed into various regular sets of figures, such as triangular, hexangular, circular, &c. which formed so many different constellations; another, that they were composed of a beautiful suit, of well ranged and harmonious groups; another, that they were disposed after the manner of flowers, which he had seen growing in parterres in some garden; another, that they were formed in such a position, as resembled the shape of various images, either mystic or natural. In fact, there would be no body, that would not attribute to them some most beautiful resemblance, or imitation, of those things which he had ever seen, that seemed most pleasing to him, either in art, or nature. Notwithstanding which, they would all deceive themselves, and be greatly surprised, upon the firmament afterwards being displayed to their view, to find the stars placed and ranged in a position, quite different and distinct from all they had imagined.
SECT. VI.
XXI. Thus it frequently happens, that men think in one manner, and God operates in another. Men suppose, and they suppose right, that the works of God are all executed with order, and in proportion; but although they suppose well, they reason ill; because they think there is no other order and proportion, than that which comes within the reach of their comprehension. The works of God, it is true are wrought with proportion; but with a sublime proportion, which is much superior to our rules. It is blind temerity in man, to imagine that God in his works, is to conform himself to our human gross ideas of proportions.
XXII. It was a confidence in such proportions, that caused Pythagoras to err egregiously in his dimensions of the magnitude, and his calculation of the distance of the heavens, which he thought to compute, by the numerical series of the intervals of music. And others were not much wiser than Pythagoras, who by fancying they had found some special perfection in the number four, chose to stamp it on, and regulate all the operations of nature by it. From hence came the four elements, the four first qualities, the four cardinal points of the globe, the four quarters of the year, and the four humours of the body.
SECT. VII.
XXIII. If even in those consequences, which to all human appearance, we deduce immediately from the truths which nature herself presents to our senses, we are sometimes liable to be mistaken; what dependance can we place in those, that are founded on principles, which without consulting nature, are established by our fancy? What consequence to all appearance could seem better inferred, than that of the repugnance of nature to a vacuum, founded on the palpable experiment of the water rising in the pump? But by the light of innumerable other experiments, the mistake was discovered; and it was found out, that the true cause of that, and all such-like phænomena, was the weight of the air.
XXIV. We see with our eyes, whether we explain the cause of it as proceeding from an intrinsic quality, or from attraction, or from impulse, that gravity precipitates bodies with a swift movement towards the earth. It seems most natural to suppose, by reasoning from the famous axiom, sicut se habet simpliciter ad simpliciter, ita magis ad magis, that to a duplicate gravity, there would correspond a duplicate acceleration of motion. But the fact differs widely from this proportion.
XXV. It is plain, that air is much more subtle and thin than water. Who from hence, would not infer as an unavoidable consequence, that air must penetrate all bodies which water penetrates? Notwithstanding this, we see that water penetrates paper, which air does not penetrate, or it penetrates it in so small a degree, or so slowly, that we look upon it as next to no penetration at all.
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.
L. There is a certain delusion, that is very fortunate for the apothecaries, and very fatal to the sick, that is derived from a persuasion in many of these last, that their diseases would be eternal, or incurable, without the help of medicine; although they see every day, others cured of the same diseases, without this aid; and although the disorder was of so slight a sort, that all those who did nothing but leave nature to itself, recovered from it, he who called in a physician, upon his getting well, thanked the doctor for his cure, when in reality, he perhaps did nothing but delay it. I protest that when catarrhs have been epidemical, I have in various instances observed, that they lasted as long with those who took medicines, as they did with those who took none; and the only difference that I could perceive between them was, that the last recovered their natural state of robustness as soon as the catarrh left them; and that those who had taken physic, did not recover it till several days afterwards.
LI. There is another mistake said to be built upon experience, under the deception of which, many shelter themselves, and pretend, in opposition to those who differ from them in opinion, to justify the necessity of plentiful evacuations. The rigid Helmonists, or sectaries of Van Helmont, reprobate as prejudicial, purging and bleeding, in every case whatever; and in opposition to this doctrine, is urged the common experience, deduced from the cases of an infinite number of patients, who have been purged and blooded, and have all done well; and that there have been some weeks in sickly times, in which one physician has ordered a hundred patients to be purged, and as many to be blooded, and that not one of them has died. How then in opposition to this experience, say the Galenists, can any one pretend to insist, that bleeding and purging do harm?
LII. I do not undertake to defend the Helmonists, nor do I consider their opinion, as more probable than the contrary one; but I say, that from the experience alledged, nothing can be concluded to their prejudice. We should suppose, that those who exclaim against purging and bleeding, do not think them so pernicious, as to be fatal to all those who undergo these operations; for even supposing them to be injurious, they are not capable of destroying a man in perfect health, nor one that is visited by a slight disorder. I believe, that although an intemperate use of them kills many, they are chiefly those who are affected with some obstinate disease; for in these cases, when nature is much weakened by struggling with a powerful disorder, if you add a fresh enemy for her to encounter in the imagined remedy, you compleat her overthrow, and lay her prostrate on the earth. But those who are affected with a disease that is not dangerous, (and there are many of this sort, which in appearance seem violent ones,) generally preserve a sufficient degree of strength, to resist both the distemper, and some unnecessary bleedings and purgings; and although these may weaken the natural faculties, and retard the cure, they very seldom are known to deprive the patient of life.
LIII. That the number of mild disorders, greatly exceeds that of the dangerous ones, is very plain and certain; what then can we find extraordinary, in those who are attacked with the first sort getting well, notwithstanding they may have been injudiciously purged and blooded? out of a hundred patients that a physician visits in a week, seldom more than one or two of them labour under dangerous disorders. It is customary with many people to send for the doctor, upon being attacked with a slight inflammation, a catarrh, an ephemeris or fever of a day, a fluxion of the eyes, a repletion of the stomach, and such kind of indispositions; and if he happens to be one of the common or vulgar sort, he seldom fails to purge and bleed. But admitting that the purging and bleeding were never so improperly administered, does it follow from thence, that the patient must die? Or why should this be an unavoidable consequence, if in the same situation, he had been stabbed with a poignard that had not penetrated very deep, or that had not wounded a vital part, he would have escaped with his life?
LIV. As I observed before, I am neither a partizan of the Helmonists, nor a favourer of the Galenists; but I look upon it as a thing certain, that an intemperate use of purging and bleeding, has destroyed many men, and especially, if administered when nature is much weakened; notwithstanding which, I am persuaded that they are serviceable in many cases. Whether they are absolutely necessary, and whether patients could not do well, if other remedies were substituted in their places, is a point I will not take upon me to determine; and especially, when I have fresh in my memory, the declaration of a physician, whose authority has great weight with me. This is Lucas Tozzi, a famous Italian physician, who in his exposition of the third aphorism of the first book of Hippocrates, Habitus Athletarum, &c. after combating and controverting the usefulness of bleeding, with seemingly very efficacious and persuasive reasoning, he asserts, and offers to prove, that it is not necessary in any one of the diseases, in which the Galenists insist it cannot be dispensed with; and in answer to the experience they alledge of its utility, he quotes his own; and says, if they appeal to experience, and insist that it is evident from thence, that many people have been cured of various disorders by blood-letting; I reply, that in the hospital of the Anunciada at Naples, where I have officiated as physician many years, I have cured in a short space of time, and without taking from them one drop of blood, hundreds and thousands of patients, who have been attacked with some one or other of the following disorders, frensies, pleurisies, quinsies, inflammations of the liver, spitting of blood, erysipelases, and all kinds of fevers.
LV. What shall we say to this? Lucas Tozzi was not only a great theorist, but also a most expert, successful, and much esteemed practitioner, and as such, his advice was solicited with anxiety by people of the first rank. If he without bleeding cured all those disorders, which in the common opinion stand most in need of that evacuation, and not only cured them, but did it in a short time, what diseases must they be which cannot be cured without blood-letting?
LVI. And it is very remarkable, that in the same manner the Galenists endeavour to deduce from experience the necessity of blood-letting in many diseases, they endeavour also to establish the preference, that should be given to drawing blood in particular disorders, from particular veins, such as the hepatic, and cephalic. Anatomy however, makes it as clear as the sun at noon-day, that this preference is not grounded on any solid foundation, and that the cephalic vein bears no more relation to, nor is any more connected with the head, than the hepatic, nor the hepatic with the liver, than the cephalic; and that all the veins of the same arm, communicate indifferently with all parts of the body, as the laws of circulation demonstrate; and as that observation which was pretended to be derived from experience, was founded in mistake, it is not improbable, that that which is generally alledged in favour of bleeding, may be so likewise.
LVII. What appears to me is, that the rule so much cried up by the Galenists, and which establishes the necessity of bleeding, in pleurisies, is liable to so many exceptions, that we ought not to regard it as a general one; and we have observed in another part of our works, that in some epidemical pleurisies, it has been found to be evidently injurious. It is but a little while ago, that a learned French physician, whose works are mentioned in the Memoirs of Trevoux, wrote strongly against bleeding in winter pleurisies and peripneumonies; and his reasoning had great weight with some eminent physicians of Paris. I can certify, that in the last winter 1731, when many people were attacked with pleurisies in this country, it was generally remarked, and we received informations to the same effect from all quarters, that those who were blooded died, and that those who were not did well.
LVIII. I would have it understood, that I wish all I have said, with respect to the utility or inutility of purging and bleeding in general, should be considered as the sentiments of a man, who takes no side in the dispute, but who proposes what he advances problematically, and with a view of convincing the world, that in order to avoid being misled, they should examine with great attention and exactness, any observation that is alledged to be founded on experience, for this is the principal object I had in view, in writing this discourse.
LIX. It would argue weakness and want of judgment, for any one to esteem a thing as a remedy for a particular disease, without reflecting and making a remark, the propriety of which must stare every man in the face, and that is, comparing the success of the practice of those who use that medicine, with that of those who do not make use of it. There have been physicians, who have declared themselves enemies to the administration of the bark; but notwithstanding this, there is no body at this day, who disputes its febrifuge efficacy in intermittent cases; for experience shews, that it will stop the fit, although it may return again afterwards, and although in the opinion of some people, the medicine may leave some bad impression on the body. If purging and bleeding would have the same effect, in some sort of fevers, we should all agree in attributing to them a febrifuge virtue; notwithstanding that some practitioners, might give the preference to other remedies, as more safe, and better adapted. But this is so far from being the case with respect to these evacuations, that their efficacy of removing fevers, is at this day strongly contested, for experience has not yet manifested, that they are remedies for these disorders, in any degree or manner, that is not exceedingly doubtful or disputable.
SECT. XIV.
LX. As far as the nature of the case will permit us (for all things are not capable of being mathematically or decisively demonstrated), we should endeavour to discover the truth, by imitating the diligence and attention which many English physicians exercised, in examining into the eligibility of the precautionary remedy called inoculation, practised by the Turks, to elude the fatal effects of the small-pox. This is a subject, that has been much talked on in other kingdoms for some years; although in Spain we have hardly heard it mentioned. The event of communicating the infection in this way, most generally is, that the person inoculated has the distemper very lightly, and is hardly ever obliged through the whole course of the disease, to keep his bed.
LXI. The account of this precautionary method, was brought to England by one Maitland, who was surgeon to Mr. Wortley Mountague, his Britannic majesty’s ambassador at the Porte, and was from thence communicated to the other nations of Europe. Maitland had observed, that this practice was almost universal in all the cities of the Levant, and that it was attended with wonderful success. He communicated these remarks to Mr. and Mrs. Mountague, and they had fortitude enough, upon the faith of what he had told them, to make the experiment upon a son they had with them of six years old, which being attended with success, they repeated it upon another of their children when they returned to England. Many were animated with these examples and these accounts; and the practice of inoculation, began to be much approved, and much adopted in England, notwithstanding it was greatly opposed, and objected to by some people there, and by many in other countries; and especially by the physicians of Paris, who exclaimed strongly against it.
LXII. But as this contest was such a one, as ought not to be determined by speculative reasoning, an appeal was made to experience, which appeal, was prosecuted in such a manner by those who were advocates for the practice, as seemed to exclude all doubt and perplexity. Physicians who resided in different parts of the kingdom, were requested to give accounts of the success of their practice by this method, and to transmit them to London, which when received, were printed and published. By these accounts, two facts were established; the first was, that inoculation freed the patient from the danger of a second infection; and the second was, that those to whom the small-pox was communicated in this way, very rarely died; and although it is true that some few of them miscarried, they were mostly such, as were afflicted with some other disorder at the time of their inoculation, of which they would have died, if they had not had the small-pox; but these altogether, did not amount to but very little more than a tenth part of those, who perished by catching it in the natural way; for by the best calculation they could make, one out of eight died of the last, and not above one in eighty of the first.
LXIII. This is the account I have read of this matter in the Memoirs of Trevoux; to which some may object, that it is possible the relations of the cases, were not published so faithfully as they were received. To this I answer, that it is probable great pains were taken in making the enquiries, and great fidelity observed in publishing the accounts, as the Memoirs of Trevoux tell us, that upon the strength of their authority, some of the royal family of England were inoculated.
LXIV. And let it not be insisted in opposition to this, that if the fact had been so well established, it could have admitted of no contradiction. They know little of the human passions, who think this remark a solid one. Those who contradict, either through blind prepossession, or from motives of emulation, interest, or envy, seldom submit, or will own themselves convinced by proofs that are self-evident; nor is there any species of evidence, that can bar every door, at which a false subterfuge may steal in, nor against the intrusion of a thousand sophistical objections, introduced by those, who are under the dominion of the beforenamed passions. I speak feelingly of this matter, having had woeful experience of the truth of what I assert, since I first began to write for the public.
LXV. In reality, some of the objections that were made to inoculation, were the most ridiculous in the world. Some rigid Presbyterians, made the cause of religion interested in the question, and asserted, that that practice, was an affront to the sovereignty, and an opposition to the decrees of God; and one of them declared in his preaching, that it was a diabolical invention, for the devil by inoculation had communicated the small-pox to Job, which was the distemper that so sorely afflicted that holy Patriarch. Into what absurdities, does a violent ardour hurry a man in a controversy! Of all sensible human beings, there are none so nearly allied to mad men, as passionate disputants.
LXVI. Towards the conclusion of this virulent contest, a very curious circumstance came to light, which was, that this precautionary method which had made so much noise, and which had generally been supposed to have been brought from Turkey, had for ages before, been in use in the island of Great Britain itself; for that it had been practised from time immemorial, in the southern parts of the principality of Wales, where they communicated the infection in two ways either by rubbing some of the variolous matter hard on the skin of the person to whom the distemper was to be given, or else by dipping a needle into that matter, and pricking his skin with it; and as they gave the person from whom the matter was taken a small sum of money, this was called buying the small pox; and they produce very authentic testimonies, that scarce any one of those who came by the distemper in this manner died, and that there was no instance of a person who had acquired the disease in this way, ever having had it a second time.