Part 6

LV. As the audience before whom I propound this reflection, is composed chiefly of the followers of Aristotle, methinks I hear them exclaim, that if we were to collect the suffrages of the academic professors, we should find most votes in favour of his opinion. To this, I reply in the first place, that although a plurality of sectaries, gives greater extrinsic probability to an opinion, still it does not afford certainty, nor intrinsic probability; and the question here, is not whether Aristotle’s opinion is the most probable, but whether it is certain. I reply secondly, that it is doubtful, if we were to include the professors who teach physics in all nations, whether we should in reality find a majority of votes in favour of Aristotle; and unless we could prove by some authentic instrument, that God has limited the knowledge of philosophy to our nation only, and has excluded all others from inheriting the science, I do not know upon what pretension we can ground a right, of admitting none but Spaniards to vote in the question. Some of our antient professors say, that we should not regard the opinions of strangers, because they are novelists; but at the same time, strangers reply, that we should take no account of what the Spaniards assert, because they are obstinate and wrong-headed, and that there is no proof, be it ever so clear, that will make them depart from their old opinions; to which they add, that in Spain, they do not follow Aristotle from choice, but from necessity; for that it requires an heroic spirit, to contradict any thing that has been advanced by Aristotle in that kingdom, where whoever dares venture to oppose him, is instantly assailed by tempests of injuries, which fall on his head like violent hail storms. Nor is even an heroic spirit, sufficient to enable a man to support such an opposition, because the duty of obedience, obliges people not to depart from the line of their school; and this is also frequently the case, in other countries; and from hence, some Anti-Aristotelites have insisted, that the plurality of votes in favour of Aristotle should not prevail, because they cannot be supposed to be free.

LVI. But abstracted from the quantum of extrinsic probability, contained in the doctrine of Aristotle respecting the elements; I assert, that upon a strict examination, you will not find more truth contained in his sentiments, than in those of his adversaries. This opinion, I deduce from the position, that his first qualities consist of four, to wit, heat, cold, wet, and dry, from which in exact proportion, he attributes one to be impregnated in the highest degree with each element, and another near to the highest. This proof, goes lame in innumerable particulars. First, the giving to these qualities the title of first, is conferring a mere voluntary dignity on them, and especially, when we know the invincible difficulty, that attends establishing, that all the others result from them. Secondly, it is very doubtful, whether all the four beforementioned, can properly be called qualities; for many Aristotelites, and with great colour of reason, deny humidity and dryness to be such. That which is humid, is not so from any quality it possesses in itself, but because it has imbibed into its pores some foreign liquid substance, and let that be evaporated, and it will remain dry; from which we may conclude, that humidity is a substance, and that dryness consists in the want of that substance. Thirdly, the appropriating these as two of the four elements, is done without any foundation or reason. In the next place, how can they prove that water is cold in the highest degree? If this was true it would kill us; neither can they prove it so, in a more moderate, or secondary degree, for we are taught by experience, it is indifferent to both cold and heat, according to the agent that is applied to it. It is heated by the fire; and remove it from the fire, and it becomes cool again, not because it has any propensity or natural disposition to be cold, but because it is made so, by the cool atmosphere which surrounds it. There are many other very grave objections to be urged against this doctrine of the four qualities; and therefore the foundation upon which it is built, and the reasoning deduced from it to establish the quaternian system of the elements, are both very slight and futil.

LVII. The second argument, is built on the correspondence of the four humours of the body, with the four Aristotelic elements; that is to say, the blood with the air, the choler with the fire, the melancholy with the earth, and the pituitous with the water. But this puts us in a worse situation than we were before. In the first place, it is a doubt among the medical people, whether the humours of our bodies consist precisely of four. Some say they are more, and others that they are less. Some add to the four, the lymph, the pancreatic juice, and the nervous fluid; and some again will not admit, that there is any other humour except the blood. Secondly, if the four elements correspond only with the four humours, we are left without an element to correspond with the solids, which on account of the hardness of their substance, might with more propriety be compared to the earth, than to the melancholy humour, which is beyond comparison less hard and solid than the other. Thirdly, in the same voluntary manner, with which they assign four elements to correspond with the four humours, they may assign one element to correspond with the flesh, another with the bones, another with the marrow, another with the fat, or adipose substance, another with the tendons, and so on. Fourthly, in order to reason justly upon the human body, or animal species, we should not seek for four substances that are analogous to the four humours, but for four that enter into all the mixtures; for the question, relates to elements that partake of the composition of all mixtures in general, and not precisely of the animal. But what traces can we discern, of four humours, or four substances, equivalent to these, either in minerals, or plants?

LVIII. The third argument in support of this quaternian system, is pretended to be derived from experience; for it is alledged, that when a piece of wood is burning, we see it resolve itself into the four Aristotelic elements. At first it emits a small portion of water; then it takes fire; the fire is followed by smoke, which we know to be of an aerial nature, by its ascending to the airy region; and last of all, there remains a portion of earth in the ashes.

LIX. Although as Etmuller says, in matters of physics and medicine, _præstat unum experimentum centum rationibus_, still, the experiment just alledged is so defective, that it is not of more value than the arguments before urged. In the first place, dry wood, may as properly be called a mixture as green wood, notwithstanding which, it emits no water upon being laid on the fire. Secondly, as we are here treating of the elements in general which enter into, and make a part of the composition of every species of mixture, the fire should produce the same appearances, and have the same effect upon them, that it has upon the wood; but this does not happen, for minerals laid on the fire emit no water, unless it is when they have imbibed some foreign moisture. Thirdly, the chymists by means of fire differently applied, extract from wood and other mixtures, various substances, which differ from those four that are produced from the wood in the ordinary way of burning it; and it seems reasonable from hence, that we should augment the number of the elements. Fourthly, we do not know whether these substances pre-existed in the wood, or whether they were produced _de novo_ by the fire. Fifthly, the ash is not earth, nor an elemental or simple body as is supposed, for there may be separated from it a large portion of salt, which is a distinct substance from either of the four; for it is neither earth, air, water, or fire. Sixthly, neither is the smoke air, as is manifest from the soot which condenses in the chimney. If I should be told, that in the smoke is contained a variety of particles, some of which compose the soot, which remains in the chimney, and others which mount higher, and are impregnated with the atmosphere, and become air; I reply, that in consequence of this, they should admit of a fifth element of soot; or to speak more properly, of five or six additional elements; for Mr. Boyle informs us, that the chymists can extract from soot, five or six different substances. Finally, all that becomes ashes, existed before in the form of fire; from whence it follows, that the form of ashes is a new production, for matter cannot exist under two substantial forms at one and the same time; and consequently, the elemental form of earth which the Aristotelites ascribe to the ashes, could not pre-exist in the mixture, but must be a new production. This objection militates principally against the Aristotelic principles; but others might be formed in different shapes, against every system whatever.

LX. I have combated only the Aristotelic opinion of the elements, not because the others are not incumbered with equal difficulties, and exposed to equal objections, but because in Spain, we suppose the others to be perplexing, and even improbable, and conclude that of the four elements, to be just and right; I therefore chose to attack this system, to let my countrymen see, that we know nothing with certainty respecting the elements.

SECT. XIV.

LXI. I have remarked before, that if we are ignorant of what the elemental bodies consist, we cannot possibly know the nature of the mixtures. But even if we could ascertain what the elements are, we should still remain in profound philosophical ignorance with respect to the component parts, of both them and the mixtures; for admitting the four following, air, fire, water, and earth, to be elements of all the mixtures; who has yet ascertained the nature of those four bodies? Aristotle only reasoned upon their qualities, and this he did with so little precision, that all he said may be looked upon as doubtful, for he had no solid principle, from whence he inferred, that they possessed the properties which he attributed to them; but drew all his conclusions, from an ideal proportion which struck his own imagination; and respecting which, it has since been proved, that he was mistaken. He says that air is hot, and fire dry in the highest degree; but in our essay on physical paradoxes, we have proved that the air is not hot; and according to Aristotle’s definition of humidity, we may infer, that a flame is humid, for it cannot be contained within its own bounds, but pervades other regions. We also proved in our essay on physical paradoxes, that elemental fire is not hot in the highest degree; and to what I said there, I will add in this place, that experience shews us, one fire is hotter than another, and has greater power to heat or melt substances, either in consequence of its greater bulk, or on account of the matter with which it is made, or the manner the place is disposed and contrived, in which it is lighted; from all which it may be inferred, that fire in its nature is not hot in the highest degree, for if it was, as in every fire the nature of fire is preserved, every fire would be hot in the highest degree, and of course, could not be exceeded in heat by another fire.

LXII. Aristotle however, did no more than assign false or uncertain qualities to his four elements, and left untouched, substantial nature which is the root of them; and those who succeeded him in all after-ages, if they aimed at more, attained no more. The sectaries of Aristotle content themselves with saying of the elements, what they say of all other natural compositions; that is, that they are constituted of matter in physical forms, are real incompleat entities, and evidently distinct from each other. By all which, admitting this description to be right, they teach us nothing, till they explain to us, of what the physical form consists, and what is the specific nature of the physical form, in every natural composition. But their system explained in the general way, in which they themselves define it, is strongly combated by the modern philosophers, who find an insurmountable difficulty in the generation of the material forms, not being able to comprehend, how their production can be any thing else but a new creation; for the arguments the Aristotelites fly to, of deducing them from the power of the matter, contain nothing but words, void of all real signification; and truly Aristotle himself having said, that the form is one of the principles of a natural entity, and that the principles are those things, which are neither made from their own substance, nor from that of any other entity whatever, shew them to be words which have no fixed meaning: _Quæ nec ex se, nec ex aliis, sed ex quibus omnia fiunt_; how then can we reconcile this doctrine, with the form being made of the matter?

SECT. XV.

LXIII. But have the moderns who exclaim so much against Aristotle, hit upon the truth? By no means. They have reasoned more boldly, but not with better success. They tell us, that the texture, collocation, figure, and motion of the particles, produce all the operations of nature, without the necessity of having recourse for this purpose, to accidental or substantial forms; but by saying this, they expose themselves to the same fault which they reprehend in the Aristotelites, which is that of speaking too generally; for as these last, do not explain or define, of what the substantial form consists which distinguishes one entity from another, neither do the others determine, the texture, co-ordination, and figure of the particles which appertain, and are proper to each composition; in consequence of which, they all involve themselves in innumerable difficulties, which they reciprocally object against each other. The Cartesian system appears chimerical to the Gassendists, and the Maignanists; and these two last parties, although they agree in assigning the Atoms as the principles, and elements of all material things, oppose one another in various particulars, it being a principle with the Maignanists, that the Atoms are different in species, and with the Gassendists, that they differ only in figure; all of which systems, are exposed to be combated by arguments that are terribly strong.

SECT. XVI.

LXIV. From all that has been said, it may be evidently concluded, that we know nothing of the nature of that principal object of physics, _an ens mobile_, either taken as confined to individuals, or considered with respect to the species, or contemplated in an abstracted sense, as relating to the gradations, of lowest, inferior, or supreme. What one sect affirms, another denies, and the worst is, that, attend to the reasoning of which of them you will, you will find the arguments against the system of each, stronger than the proofs in favour of it. On this account, Lactantius said wisely, that philosophers have swords, but no shields: _Gladium habent, scutum non habent._ They produce penetrating arguments wherewith to assail the opinions of their opponents, but not solid solutions, wherewith to defend their own. What can we do then in such a case? Why nothing but suspend our judgment, till some angel shall decide the contest.

LXV. Perhaps some one will remark to me, that the substantial nature of things is at a great distance from our view, and that therefore it is not wonderful, that we have not yet penetrated into the inmost recesses of philosophy; for that without advancing so far, we may find sufficient matter whereon to exercise our speculations, in contemplating the ordinary phenomena of nature, and by endeavouring to discover their proximate causes; which attempt, may possibly be crowned with success, by observing and reasoning upon every species of movement which is performed by an entity, that has motion or circulation, according to the nature of such an entity.

LXVI. I will acknowledge, that philosophy helps us to reason upon natural phenomena, and to enquire into their more immediate causes; but in doing this, we frequently wander in the dark, and are much exposed to be interrupted by impediments, produced by ignorance and doubts; except it is in the case of a few truths, the discovery of which, we owe to the light of experience; and this fact is evinced, with respect to the very instance of motion which has been just alledged.

LXVII. With regard to the movements of generation, corruption, alteration, augmentation, and the rest, which are considered as distinct from local motion, you can find nothing that is not questionable, both in the schools of the Aristotelites, and in those of the modern philosophers. The very definition of motion in general, which was given by Aristotle, some reject as obscure, others as perplexed, and others as nugatory. The movements we are now treating of, in the opinion of Aristotle, are acquisitions of new forms, either substantial, or accidental; but the Moderns, who deny the existence of all material forms, object to this definition of those movements. Even among the Aristotelites themselves, it is not agreed, whether motion is not influenced by passion; nor whether the first, is not obedient as a passive agent to the last. And thus in every thing else, it is all question, and all dispute.

SECT. XVII.

LXVIII. And why should we be surprized that with respect to these movements, which as we may say, nature executes behind the curtain, human understanding has made so little, or next to no advances? what we ought more to wonder at, is, that it happens the same with respect to all local motion, which lies so plain and open to our observation.

LXIX. The motion with which heavy bodies descend, is the most frequent and common to our view. And what do we know of this? Of its properties very little; of its causes nothing. We know it acquires some degree of acceleration in its passage, because we see it; but what is the proportion of the increased acceleration, is matter of great debate, both among the philosophers, and mathematicians. We know that it is a motion of descent, but we do not know whether its course is directed to the centre, or the axis of the earth. The cause of this motion remains so hidden, that the philosophers to this day, have given no opinion concerning it, that I will not venture to pronounce an absurd one. The Aristotelites, by saying the cause of this motion proceeds from an innate disposition to move in every thing, say nothing, unless they point out the particular virtue or faculty, which excites motion in heavy bodies, for what we have just mentioned, is the reason they generally assign for all species of movements. They should not be allowed to dispute or controvert what they themselves have advanced; and if they should attempt to give a more rigorous definition of their opinion, they would fall into a still greater absurdity; which made the learned Father Saguens say, _Quis non palpat crassitiem hujus chimericæ opinionis?_ The Cartesians to account for this phenomenon, recur to the vertical motion of the subtil matter, which separating itself from the earth, and pursuing the angle or direction of tangents to the circle, impels heavy bodies to descend. But this reasoning has been confuted by most efficacious mathematical arguments. Gassendo invented an effluvia composed of terraqueous corpuscles, which mount into the air, and penetrate the pores of heavy bodies, which they generally encounter, and after turning their first course into a descending one, impel them downwards. Nothing has so much convinced me of the great difficulty of this question, as seeing a man of the subtil ingenuity of Gassendo, recur for the solution of it, to a fiction destitute of all probability; and which is exposed to invincible objections. Father Maignan, and his followers also, make use of the terraqueous effluvia for the solution of this difficulty; they do not allow that they act by impulse, but that by their sympathetic and magnetic virtue, when they come in contact with heavy bodies, they dispose them to descend.

LXX. It is very probable, and perhaps more than probable, that the ascent of light bodies, is caused by the descent of heavy ones; because the heavy body has power, in consequence of the impetus of its descent, to occupy the lower station, where meeting with the light body, it obliges him to leave that situation, and to mount upwards; for many argue with great colour of reason, that there is no such thing as absolute lightness to be conceived in any body whatever, nor is such a quality necessary, a respective or comparative lightness, being sufficient to answer every purpose. Thus we say a body is light, not because it is void of gravity, but because it is less heavy than the one with which we compare it. In the same manner we say the air is light, not because it is not ponderous, but because it is less so, than earth, water, and all the other bodies that surround us; and that no other levity but the respective, is necessary to cause bodies which we call light to ascend, may be clearly seen in the case of oil, which notwithstanding that it is heavy, if you pour a quantity of water into the vessel where it is, the water on account of its superior gravity, will occupy the inferior station, and oblige the oil which was at the bottom to ascend. The same thing happens with regard to air. If you dig a ditch to any depth in dry ground, the air will descend and occupy the whole of it; and there is no other way to dispossess the air from the bottom, and to make it rise upwards, but conveying water into the ditch, or by throwing into it some body that is heavier than the air.

LXXI. It is not owing to the principles of physics, but to experience, that we understand the little we know of this matter; and with respect to this little, there still remains great difficulties for philosophers to contemplate; and the greatest of all, is ascertaining the cause of the ascent of vapours to the region of the air. It is certain, that vapours are nothing else but water, resolved into exceedingly minute particles. The water however being heavier than air, how can the water arise to the height occupied by the clouds? Every particle of water notwithstanding it weighs very little, is much heavier than a particle of air of equal size, and the greater or less gravity of liquids, for the purpose of their impelling one another, is computed in the gross, and not according to the proportion of globules of equal size; and we know that a pound of water, will cause a quarter of an hundred of oil to rise in a vessel.