But let us grant to Ariftotle, That there are four Elements, fuch as he pretends •, two of which are heavy, viz. Earth and Water •, and the two other light of their own Nature, viz. Fire and Air; what Confequence may be drawn from thence, for the Knowledge of the Univerfe > Thofe four Elements are not the vifible Fire, Air, Water*and Earth, but fomething quite different, which we know neither by the Senfes, nor by Reafon, having no diftin£t Idea of them. Let all natural Bodies be compos'd of them, fince Ariftotle has faid it: But the Nature of thofe Compounds is ftill unknown, and cannot be difcovered, but by knowing the four Elements, or the fimple Bodies of which they are made, fince the Compofed is known only by the Simple.
Fire, fays Ariftotle, is light by its own Nature; the afcending Motion is fimple: Fire is there- fore a fimple Body, fince Motion muft be proportion'd to the Moveable. Natural Bodies are compos'd of fimple, there is then Fire in all natural Bodies, but a Fire which is not like to that we fee • for Fire is often but in potentia in the Bodies that are made of it. What fignifie all thefe Peripatetick Difcourfes? That there is Fire in all Bodies, either a£lual or potential, that is to fay, that all Bodies are compos'd of fomething we fee not, and the Nature of which is wholly un- known unto us. Now we have made a very fair Progrefs.
But though Ariftotle fhews us not the Nature of Fire, and other Elements, of which all Bodies are made up; yet one may imagine, that he will at leaft difcover their principal Qualities and Properties. Let us alfo examine what he fays upon that Account.
He declares that there are four principal Qualities which belong to the Senfe of Touching, viz. l. 2. &?» Heat, Cold, Humidity and Siccity; or which all the other are compos'd. He diftributes thofe de Gene, primitive Qualities into the four Elements, afcribing Heat and Drynefs to Fire, Heat and Moifture ^ CorruP< to the Air, Cold and Moifture to Water, and Cold and Drynefs to Earth. He afTerts that Heat and Cold are aftive Qualities; but that Drynefs and Moifture are paflive. He defines Heat, What congregates Things of the fame kind; Cold, What congregates Things either of the fame, or of dif- ferent Species; Moifture, What cannot eafily be contained in its own Limit s, but is eafily kept with- in foreign Bounds; and Drynefs, What is eafily contained within its own Limits, but will hardly be adapted to the Bounds of furrounding Bodies.
Thus, according to Ariftotle, Fire is a hot and dry Element, and therefore congregates Homoge- neous Things, is eafily contained within its own Limits, and hardly within others: Air is a hot and moift Element, and therefore congregates Homogeneous Things, can hardly be kept within its own Limits, but eafily within others: Water is a cold and moift Element, and therefore congregates both Homogeneous and Heterogeneous Things, is hardly contained within its own Lhnits, but eafily with- in others: And laftly, Earth is a cold and dry Element, or fuch an one as aggregates Things, both of the fame and different Natures^ is eafily contain 'd within its own Limits, but can hardly be adapt- ed to others.
There you have the Elements explain'd, according to the Opinion of Ariftotle, or the Definitions he has given of their principal Qualities •, and becaufe, if we may believe him, the Elements are fimple Bodies, out of which others are conftituted •, and their Qualities are fimple Qualities, of which all others are compos'd, the Knowledge of thofe Elements and Qualities muft be very clear and diftinft, fince the whole Natural Philofophy, or the Knowledge of all fenfible Bodies, which are made of them, muft be deduc'd from thence.
Let us then fee what may be wanting to thofe Principles. Firft, Ariftotle fixes no diftinft Idea to the Word Quality: It cannot be known whether by Quality he underftands a real Being diftin- guifh'd from Matter, or only a Modification of Matter; he feems one while to take it in the for- mer, and at another time in the latter Senfe, I grant that in the 8th Chapter of his Categories, he defines defines Qua/ity, that by which Things are denominated Jo or fo; but that is not plain and fatisfaSto- ry. Secondly, His Definitions of the four Primitive Qualities, viz. Heat, Cold, Moifture and Drynefs, are either falle, Or ufelefs. We will begin with his Definition of Heat; Heat?-, fays he, is that which congregates Homogeneous Things.
Firft, Though that Definition fhould be true, That Heat always congregates Homogeneous Bo- dies -, yet we cannot fee how it perfectly explains the Nature of Hear.
Secondly, 'Tis falfe that Heat congregates Homogeneous Things •, for Heat diihpates the Par- ticles of Water into Vapour, inftead of heaping them together: It congregates not likewife the farts of Wine, or any Liquor or Fluid Body whatfoever, even to Quick-filver. On the contrary, it refolves and feparates both Solid and Fluid Bodies, whether of the fame or different Natures:, and if there be any, the Parts of which Fire cannot diffipate, it is not becauie.they are homoge- neous, but becaufe they are too grofs and folid to be carry'd away by the Motion of the fiery Particles.
Thirdly, Heat, in reality, can neither congregate nor fegregate the Parts of any Body whatfo- ever •, for, that the Parts of Bodies may be congregated, feparated or diffipated, they muft be mo- ved: But Heat can move nothing, or at leaft, it appears not that it can move Bodies •, for though we confider Heat with all the poflible Attention, we cannot difcover that it may communicate to Bodies a Motion which it has not it lelf. We fee, indeed, that Fire moves and feparates the Parts of fuch Bodies as lie expos'd to its Aclion, but it is not perhaps by its Heat, it being hot evident whether it has any -, it is rather by the Action of its Parts, which we vifibly perceive to be in a con- tinual Motion •, for thefe fiery Particlejjfiriking againft a Body, muft needs impart to it fomewhat of their Motion, whether there is or^Riot any Heat in Fire. If the Parts of that Body be not very folid, Fire will diflipate them; but if they be very grofs and fblid, Fire can but juft move" them, and make them flide one over the other. And Larfly, If there be a Mixture of fubtile and grofs Parts, Fire will only diihpate thofe which it can pufh lb far as to feparate them from the others. So that Fire can only feparate •, and if it congregate, 'tis only by Accident. But Ariftot/e be fcnw- aiTerts quite contrary: Separating, fays he, which fonie afcribe to Fire, is but congregating Homo- h 2,°'c."2;' &eneous Things -, for ''tis only by Accident that Fire carries off Things of different Nature.
If this Philofopher had at firft diftinguifhed the Senfation of Heat, from the Motion of the fmali Particles, of which the Bodies called hot are compofed, and had afterwards defined Heat, taken from the Motion of Parts, by faying, that Heat is what agitates and feparates the invifible Parts, of which vifiole Bodies are made up -, he would have given a tolerable definition of Heat; though not full and fatisfa&ory: becaufe it would not accurately difcover the Nature of Motion in hot Bodies.
Ariftot/e defines Cold, what congregates Bodies of the fame, or different Nature: but that De- finition is worth nothing, for Cold congregates not Bodies. To congregate them, it muft move them: but if we confult our Reafbn we fhall find, that Cold can move nothing -, for we under- ftand by that word, either what we feel when we are cold, or what caufes our Senfation. As to our Senfation, 'tis plain that it is merely Paffive, and can neither move nor drive any thing. And as to the Caufe of that Senfation, reafon tells us, if we examine things, that it is merely reft, or a CeiTation of Motion: So that Cold in Bodies being no more than the Ceilation of that fort of Motion which attends Heat, 'tis evident that if Heat feparate, Cold does not. And therefore Cold coacervates neither things of the fame, nor of different nature-, fince what cannot drive on Bodies cannot amafs them together. In a word, as it does nothing, it muft needs congregate nothing.
Ariftot/e judging of things by his Senfes, imagin'd Cold to be as pofitive as Heat; and becaufe the Senfations of Heat and Cold are both real and pofitive, he fuppofes them both likewife to be attive Qualities: and indeed, if we follow the Imprefiions of the Senfes, we fhall be apt to be- lieve that Cold is a very active Quality; fince cold Water congeals,, accumulates, and hardens in a moment melted Gold and Lead, when they are pour'd upon it from a Crucible •, though the Heat of thofe Metals be yet ftrong enough to feparate the Parts of the Bodies which they touch.
'Tis plain, by what has been laid in the Firft Book, concerning the Errours of the Senfes, That if we relye upon the Judgment the Senfes make of the Qualities of fenfible Bodies, 'tis impofTible to difcover any certain and undeniable Truth, that may ferve as a Principle to proceed in the Knowledge of Nature. For one cannot fo much as difcover that way, what things are hot, and what cold; amongft feveral Perfons, who touch luke-warm Water, it feels cold to thofe that are See Book I. hot, and hot to thofe that are cold. And if we fuppofe Fifties fufceptible of Senfation, 'tis very to°X 15!' Pr°bable that they feel it warm, when all or moft Men feel it cold. It is the fame with Air, that feems to be hot or cold, according to the different Difpofitions of the Bodies of thofe that are ex- pofed to it. Ariftot/e pretends that it is hot, but I fanfie that the Nothern Inhabitants are of ano- ther Opinion, fince feveral learned Men, whofe Climate is as hot as that of Greece, have affer- ted it to be cold. But that Queftion, which has made fo much noife in the Schools, will never be refolv'd, as long as no diftinft Idea fhall be affixed to the Word Heat.
The Definitions Ariftot/e lays down of Heat and Cold cannot fettle that Idea. For Inftance, Air, and even Water, though never fo hot and* icalding, congregate the parts of melted Lead to- gether with thofe of any other Metal whatfoever. Air conglutinates all forts of Fat joyn'd with Gums, or any other folid Bodies. And he fhall be a very formal Pcripatetick, who fhould think of cxpofing Maftich, to the Air, to feparate the pitchy from the Earthy part, and other com- pound Bodies to uncompouml them, And therefore Air is not hot, according to the Definition which Chap. V. The Search after Truth. 6$ which Ariliotlc gives of Heat. Air fepa rates Liquors from the Bodies that are imbued with them, hardens Clay, dries ipread Linen, though Ariftotle makes it moift, and ib is hot and drying, ac- cording to the fame Definition 5 therefore it cannot, be determined by that Definition, whether or no Air is hot. It may indeed be alferted that Air is hot in reference to Clay, fince it feparates the Water from the Earthy Part. But mult we try all the various Eftecfs of Air upon all Bodies, before we can be allured, whether there is Heat in the Air we breath in? If it be fo, we fhall ne- ver be fare of it, and 'tis as good not to philofophize at all upon the Air we relpire, but upon iome certain pure and elementary Air, nor to be found here below, of which we can very dog- matically albert, with Ariftotle, that it is hot, without giving the leaff Proof of it, nor even diltincfly knowing what we underlfand either by that Air, or by the Heat afcribed to it. For thus we [hail lay down Principles fcarce to be deftroyed; not becaufe of their Plainneft and Certainty, but by reafon of their Darknefs, and their being like to Apparitions, which cannot be wounded, became they have not a Body.
I fhall not infill, upon Anftetle's Definitions of Moifture and Drynefs; it being evident^ that they explain not their Nature. For according to thole Definitions, Fire is not dry, fince it is not eafily contained within its own limits; and Ice is not moift, fince it keeps within its proper L e-unds, and can difficultly be adapted to external Bounds. But if fluid be underltood by the Word!.\.'>>/id, or moift, it may again be laid, that Ice is not moift; and that Flame, melted Gold, and Lead, are veiy humid. If by humid 01 moift 'he underftood what eafily cleaves to anything, Ice is not humid, and Pitch, Fat, and Oil, are moiffer than Water, fince they cleave to Bodies more ftrongly than it does. Quick-lilver is moift in that fenfe, for it cleaves to Metals; where- as Water is not perfectly moift, fince it cleaves not to molt of them. So that 'tis unferviceable to have recourle to the Teftimony of the Senfes, to defend the Opinions of Ariftotle.
But without farther examining his wonderful Definitions of the four Elementary Qualities, let us fappoiethit whatever the Senfes reach us of thole Qualities is inccnteftable: let usmufter up ail our Faith, and believe all thole Definitions very accurate: Only let it be allowed us to en- quire whether all the Qualities of fenfible Bodies are made of thefe Elementary Qualities. Arifto- tle pretends ir, and he muft do fb indeed, iince he looks upon thole Four primitive Qualities, as the Principles of all the things which he intends to explain in his Books of Thy fie ks.
He teaches us, that Colours are produced from the Mixture of thofe Four Elementary Quali- ties; White is produced when Moifture exceeds Heat; as in old Men, when they grow gray; Black when Moifture is exhaufted, as in the Walls of Cifterns; and all other Colours by the like Mixtures: that Odours and Savours arife from different Degtees of Dtynels and Moifture, mix'd together by Heat and Cold; and that even Gravity and Levity do depend thereon. In fhort, All fenlrbte Qualities muft needs be produced, according to Ariftotle, by Two attive Principles, viz. Heat and Cold: and compofed of Two pajfive, namely, Drynefs and Moifture; that there may be ibme probable Connexion betwixt his Principles, and the Confequences he draws from them.
However 'tis yet a harder Task to perfuade us of fuch tilings, than any of thofe that have been hit':, rto related from Ariftotle. We can fcarce believe that the Earth, and other Elements, would r-r; be colour d, or vifible, if they were in their natural Purity, without Mixture of thole Ele- 5 nentary Principles, though fome learned Commentators on that Philofopher afTert it. We under- itand not what Ariftotle means when he affures us, that gray Hair is produced by Moifture, becaule " in old Men Moifture exceeds Heat \ though to illuftrate his thought we put the definition inftead of the thing defined. For it looks like an incomprehenfible piece of Nonfence to fay that the Hair of old Men becomes gray, becaule what is not eafily contained within its own Li?nits, but may be within others, exceeds what congregates homogeneous things.
And we are as hard put it to believe that Savour is well explain'd, by laying it confifts in a mixture of Drynefs, Moifture, and of Heat, efpecially when we put, inftead of thofe words, the Definitions given by that Philofopher; as it would prove ufeful, if they were juft and good. And none perhaps could forbear laughing, if inftead of the Definitions which Ariftotle gives of Hunger and Thirft when he fays, that Hunger is the defire of what is- hot and dry, and Thirft the deiire. of what is cold and moift; we fhould fubftitute the Definitions of thole words, calling Hunger the defire of that which coacervates things of the fame nature, and is eafily contained with- in its own Limit's, and difficultly loithin others; and defining Thirft, the defire of that which con- gregates things of the fame and different natures, and which can hardly be contained within its own bounds, but is eafily kept within others.
Suiely 'tis a very uleful Rule to know whether Terms have been well defined, and to avoid miftakes in reafoning, often to put the Definition inftead of the thing defined; for that fhews whe- ther rhe words are equivocal, and the Meafures of the Relations falfe and imperfect, or whether we argue confequently. If it be fo, what Judgment can be made of Ariftotle' % Arguments, which become an impertinent and ridiculous Nonfence, when we make ufe of that Rule? and what may aifo be faid of all thofe who argue upon the falfe and confufed Ideas of the Senfes, fince that Rule which preferves Light and Evidence, in all exact and folid Reafonings, brings nothing but confuiion in their Difcourles?
'Tts not poiiible to lay open the foolifh Capricioufnefs and Extravagance of Ariftotle's Expli- cations upon ail forts of matters. When he treats of fimple and ealie Subjects, his Errours are plain and obvious ro be difcover'd; but when he pretends to explain very compoied things and depending on feveral Caules, his Errours aie as much compounded as the Subje&s he fpeaks of 5 lo that it is impolhbie to unfold them all, and fet them before others, § That yd F. Malebranche Concerning Book -Vi; That great Genius, who is faid to have fo well fucceeded in his Rules for defining well, knows not i'o much as which are the things that may be defined, becaufe he puts no Diitinftion betwixt a clear and diitincf, and a fenfible Knowledge, and pretends to know and explain other things of which he has not fo much as a diftinft: Idea. Definitions ought to explicate the Nature of things, and the words of which they confitt mult raife in the Mind diftin£l and particular Notions. But 'tis impoffible to define in that manner fenfible Qualities, as Heat, Cold, Colour, Savour, &ct When you confound the Caufe with the Effecf, the Motion of Bodies With the Senfation that attends it; becaufe Senfations being Modifications of the Soul, which are not to be known by clear Ideas, but only by internal Senfation as I have explain'd it in the third Book; it is impof- fible to fix to thofe words, Ideas which we have not.
As we have Diftincf Ideas of a Circle, a Square, a Triangle, and therefore know diftin£Hy their Nature, i'o we can give good Difinitions of them, and even deduce from our Ideas of thofe Figures all their Properties, and explain them to others by fuch words as are fixed to thofe Ideas. But we cannot define either Heat or Cold, in as much as they are fenfible Qualities, becaufe we know them not diftin£fly, and by Ideas; but only by Confcience and inward Senfation.
Neither muft we define the Heat that is without us by any of its Effecfs. For if we fubftitute fuch a Definition in its place, we mall find that it will only conduce to lead us into Errour. For In- Itance, if Heat be defined what congregates bomogeneom things, without adding any thing elle, we may « by that Definition miftake for Heat fuch things as have no Relation to it. For then it might be laid, that the Loadftone collects the Filings of Iron, and feparates them from thofe of Silver, be- caufe 'tis hot -, that a Dove eats Hempfeed when it leaves other Grain, becaufe that Bird is hot -y that a covetous Man feparates his Guineas from his Silver, becaufe he is hot. In fhort, there is no impertinency, but that Definition would induce one into it, were he dull enough to follow it. And therefore that Definition explains not the nature of Heat, nor can it be imploy'd to deduce all its properties from it: fince by literally infilling upon it, we fhould draw ridiculous Conclu- fions; and by putting it inftead of the thing defined, tall into Nonfenfe.
However, it we carefully diftinguifh Heat from its Caufe; though it cannot be defined, in as much as it is a Modification of the Soul, whereof we have no Idea: yet its Caufe may be defi- ned, fince we have a diftincf Idea of Motion. But we mult obferve that Heat, taken for fuch a Motion, caufes not always in us the Senfe of Heat. For Inftance, Water is hot, fince its Parts are fluid, and in Motion, and moft probably it feels warm to Fifties, at leaft 'tis warmer than Ice, whofe Parts are more quiet; but 'tis cold to us, becaufe it has lefs Motion than the Parts of our Body •, what has lefs Motion than another, being in fome manner quiet, in refpeft of that. And therefore 'tis not with reference to the Motion of the Fibres of our Body, that. the Caufe of Heat, or the Motion that excites it, ought to be defined. We muft, if poflible, define that Motion ab- folutely, and in it felf: for then our Definition will be fubfervient to know the Nature and Proper- ties of Heat.
I hold not my felf oblig'd to examine farther the Philofophy of Ariftotle, and to extricate his fo much confus'd and puzling Errours. I have fhewn, methinks, that he proves not the Exiitence of his four Elements, and defines them wrong; that his Elementary Qualities are not fuch as he pre- tends, that he knows not their Nature, and that all the Second Qualities are not made of them -, and laftly, that though we mould grant him that all Bodies are compos'd of the four Elements, and the Second Qualities of theFirlt, his whole Syitem would ftill prove ufelefs tor the finding out ' of Truth, fince his Ideas are not clear enough to preferve Evidence in all our Reafonings. " If any doubt whether I have propos'd the true Opinions of Arifiotle, he may fatisfie himfelf by eonlulting his Books of the Heavens, and of Generation and Corruption, whence I have ex- extrafted almoft all that I have faid of him. I would relate nothing out of his Eight Books of Pbyficks, becaufe fome learned Men pretend they are but a mere Logick -, which is very apparent, fince nothing but rambling and undetermin'd Words are to be found in them.
As Arijiotle often contradict s himfelf j and that almoft all forts of Opinions may be defended by fome Paffages drawn out of him, I doubt not but fome Opinions, contrary to thofe I have alcrib'd to that Philofopher, may be prov'd out of himfelf: And I (hall not warrant for him •, but it is fufficient for me that I have the Books I have quoted, to juftifie what I have faid of him; and I care little whether thofe Books are AriftotIe\ or not; taking them for fuch, as I find them upon the publick Fame 5 for we ought not to trouble our felves with enquiring into the true Genealogy of Things, for which we have no great Efteem.
General and neceffary Directions to proceed orderly in the Search after Truth, and in the Choice of Sciences, LEST it fliould be faid, that we have only been deftroying the Reafonings of others, but eftablifh nothing certain and undeniable of our own-, it will be convenient to propoie, in few words, what Order we ought to obferve in our Studies, for the avoiding Errour: and 1 de- fign withal to fhew fome Truths and Sciences that are very neceffary, as bearing fuch a Chaiacfef of Evidence, as that we cannot withold our Content, without feeling the fecret Upbraidings of our our Chap. VI. The Search after Truth. 7 1 bur Reaibn. I fhall not explain at large thofe Truths and Sciences } that's already done, and I intend not to reprint the Works of others, but only to refer to them, and to Ihew what Order we mult keep in our Studies, to preferve Evidence in all our perceptions.
The firlt Knowledge of all, is that of the Exiftence of our Soul; all our Thoughts are fo many undeniable Demonftrations of it, for nothing is more evident, than that whatever actually thinks, is actually f bmething. But though it be eafie to know the Exiftence of our Soul, yet her Ef fence and Nature are not fo eafily difcovered. If we defire to know what fhe is, we muft take care above all, not to confound her with the things to which fhe is united. If we doubt, will, qrgtie\ we muft only believe, that the Soul is fomething that doubts, wills, argues, and nothing more' as long as we have not felt in her other Properties: for we know our Soul only by the inward Senianon we have of her. We muft not miitake her for our Body, for Blood, for Animal Spi- rits, for Fire, and many other things for which Philofophers have miftaken her. We muft be- lieve of the Soul no more than we are forced to believe of her, by a full conviction of our in- ward Senfe, for otherwiie we (hall be deceiv'd. Thus we mail know, by a fimple view, or by internal Senfation, whatever may be known of the Soul; without being obliged to long reafon- ings that might lead us into Errour. For when we reafon, Memory operates; and whereever Memory operates, there may be Errour; fuppofing our Knowledge fhould depend on fome wicked Spirics that mould take delight in deceiving us.
Though I fhculd fuppofe, for inftance, a God, who took delight in thus abufing me; yet I am perluaded that I could not be deceived in a Knowledge of Jimple 'Perception, as is that by which I know that I am, that I think, or that 2 and 2 are 4. For I am confeious to my felf, that in this extravagant Suppofition, fuch a deluding Spirit, though never fo potent, could not make me doubt that I am, or that 2 times 2 are 4 ^ becaufe I perceive thofe things with a fimple view or Perception, and without the ufe of Memory. But when I reafon, as I fee not evidently the Principles of my Reafonings, but only remember that I have evidently feen them. If that (edu- cing God mould join that Remembrance to.falfe Principles, as he might do if he pleas'd, I mould conclude nothing but what was falfe. Juft like thofe that make long Calculations -, fancying they remember that they have plainly feen that 9 times 9 are 72, or that 21 is a primitive Num- ber, or lome other Errour of that Nature, draw falfe Inferences from thence.