which is not like to that we see for Fire is often but in potentia in the Bodies that are made of it What signifie all these Peripatetick Discourses That there is Fire in all Bodies either actual or potential that is to say that all Bodies are compos'd of something we see not and the Nature of which is wholly unknown unto us Now we have made a very fair Progress But though Aristotle shews us not the Nature of Fire and other Elements of which all Bodies are made up yet one may imagine that he will at least discover their principal Qualities and Properties Let us also examine what he says upon that Account He declares that there are four principal Qualities which belong to the Sense of Touching viz. Heat Cold Humidity and Siccity of which all the other are compos'd He distributes those primitive Qualities into the four Elements ascribing Heat and Dryness to Fire Heat and Moisture to the Air Cold and Moisture to Water and Cold and Dryness to Earth He asserts that Heat and Cold are active Qualities but that Dryness and Moisture are passive He defines Heat What congregates Things of the same kind Cold What congregates Things either of the same or of different Species Moisture What cannot easily be contain'd in its own Limits but is easily kept within foreign Bounds and Dryness What is easily contain'd within its own Limits but will hardly be adapted to the Bounds of surrounding Bodies Thus according to Aristotle Fire is a hot and dry Element and therefore congregates Homogeneous Things is easily contain'd within its own Limits and hardly within others Air is a hot and moist Element and therefore congregates Homogeneous Things can hardly be kept within its own Limits but easily within others Water is a cold and moist Element and therefore congregates both Homogeneous and Heterogeneous Things is hardly contain'd within its own Limits but easily within others And lastly Earth is a cold and dry Element or such an one as aggregates Things both of the same and different Natures is easily contain'd within its own Limits but can hardly be adapted to others There you have the Elements explain'd according to the Opinion of Aristotle or the Definitions he has given of their principal Qualities and because if we may believe him the Elements are simple Bodies out of which others are constituted and their Qualities are simple Qualities of which all others are compos'd the Knowledge of those Elements and Qualities must be very clear and distinct since the whole Natural Philosophy or the Knowledge of all sensible Bodies which are made of them must be deduc'd from thence Let us then see what may be wanting to those Principles First Aristotle fixes no distinct Idea to the Word Quality It cannot be known whether by Quality he understands a real Being distinguish'd from Matter or only a Modification of Matter he seems one while to take it in the former and at another time in the latter Sense I grant that in the 8th Chapter of his Categories he defines Quality that by which Things are denominated so or so but that is not plain and satisfactory Secondly His Definitions of the four Primitive Qualities viz. Heat Cold Moisture and Dryness are either false or useless We will begin with his Definition of Heat Heat says he is that which congregates Homogeneous Things First Though that Definition should be true That Heat always congregates Homogeneous Bodies yet we cannot see how it perfectly explains the Nature of Heat Secondly 'T is false that Heat congregates Homogeneous Things for Heat dissipates the Particles of Water into Vapour instead of heaping them together It congregates not likewise the Parts of Wine or any Liquor or Fluid Body whatsoever even to Quick-silver On the contrary it resolves and separates both Solid and Fluid Bodies whether of the same or different Natures and if there be any the Parts of which Fire cannot dissipate it is not because they are homogeneous but because they are too gross and solid to be carry'd away by the Motion of the fiery Particles Thirdly Heat in reality can neither congregate nor segregate the Parts of any Body whatsoever for that the Parts of Bodies may be congregated separated or dissipated they must be moved But Heat can move nothing or at least it appears not that it can move Bodies for though we consider Heat with all the possible Attention we cannot discover that it may communicate to Bodies a Motion which it has not it self We see indeed that Fire moves and separates the Parts of such Bodies as lie expos'd to its Action but it is not perhaps by its Heat it being not evident whether it has any it is rather by the Action of its Parts which we visibly perceive to be in a continual Motion for these fiery Particles striking against a Body must needs impart to it somewhat of their Motion whether there is or is not any Heat in Fire If the Parts of that Body be not very solid Fire will dissipate them but if they be very gross and solid Fire can but just move them and make them slide one over the other And Lastly If there be a Mixture of subtile and gross Parts Fire will only dissipate those which it can push so far as to separate them from the others So that Fire can only separate and if it congregate 't is only by Accident But Aristotle asserts quite contrary Separating says he which some ascribe to Fire is but congregating Homogeneous Things for 't is only by Accident that Fire carries off Things of different Nature If this Philosopher had at first distinguished the Sensation of Heat from the Motion of the small Particles of which the Bodies called hot are composed and had afterwards defined Heat taken from the Motion of Parts by saying that Heat is what agitates and separates the invisible Parts or which visible Bodies are made up he would have given a tolerable definition of Heat though not full and satisfactory because it would not accurately discover the Nature of Motion in hot Bodies Aristotle defines Cold what congregates Bodies of the same or different Nature but that Definition is worth nothing for Cold congregates not Bodies To congregate them it must move them but if we consult our Reason we shall find that Cold can move nothing for we understand by that word either what we feel when we are cold or what causes our Sensation As to our Sensation 't is plain that it is merely Passive and can neither move nor drive any thing And as to the Cause of that Sensation reason tells us if we examine things that it is merely rest or a Cessation of Motion So that Cold in Bodies being no more than the Cessation of that sort of Motion which attends Heat 't is evident that if Heat separate Cold does not And therefore Cold coacervates neither things of the same nor of different nature since what cannot drive on Bodies cannot amass
Water that feels warm to the Hands will seem cold if we wash with it any Part near the Heart Salt that is savoury to the Tongue is pricking and smarting to a Wound Sugar is sweet and Aloes very bitter to the Tongue but nothing is either sweet or bitter to the other Senses So that when we say a Thing is cold sweet bitter c. that same has no certain Signification Secondly Because different Objects can cause the same Sensation Plaister Bread Snow Sugar Salt c. are of the same Colour and yet their Whiteness is different if we judge of 'em otherwise than by the Senses And therefore when we say that Meal is white we say not any thing distinctly significative The third Reason is Because such Qualities of Bodies as occasion Sensations altogether different are however almost the same whereas such as excite very near the same Sensation are often very different The Qualities of Sweetness and Bitterness differ but little in Objects whereas the Sense of Sweet essentially differs from that of Bitter The Motions that cause Smart and Tickling differ but in more or less and yet the Sensations of Tickling and Smart are essentially different On the contrary the Sharpness of Fruit differs not so much from Bitterness as Sweetness does however that sharp Quality is the farthest from Bitterness that possibly can be For a Fruit that is sharp for being unripe must undergo a great many Changes before it grows bitter from Rottenness or too much Ripeness When Fruits are ripe they taste sweet and bitter when over-ripe Bitterness and Sweetness therefore in Fruits differ but in degree of more and less which may be the Reason why they seem sweet to some Persons whilst they taste bitter to others Nay there are those to whom Aloes seem as sweet as Honey The same may be said of all sensible Ideas so that the Words Sweet Bitter Salt Sowre Acid c. Red Green Yellow c. of such and such a Smell Savour Colour c. are all equivocal and raise no clear and distinct Idea in the Mind However School-Philosophers and the vulgar part of Men judge of all the sensible Qualities of Bodies by the Sensations they receive from them Nor do the Philosophers only judge of these sensible Qualities by their own Sensations of them but also judge of the Things themselves from the Judgments they have pass'd about sensible Qualities For from their having had Sensations of certain Qualities essentially different they judge that there is a Generation of new Forms producing those fantastick Differences Wheat appears yellow hard c. Meal white soft c. Thence upon the Testimony of their Eyes and Hands they infer That those Bodies are essentially different unless they chance to think on the Manner of the Transmutation of Wheat into Flower For Meal is nothing but bruised and ground Corn as Fire is only divided and agitated Wood as Ashes are but the grossest Parts of the divided Wood without Agitation as Glass is but Ashes whose Particles have been polished and rounded by the Attrition caus'd by the Fire And so in other Transmutations of Bodies 'T is therefore evident that sensible Words and Ideas are altogether unserviceable to a just stating and clear resolving of Questions that is to the Discovery of Truth Yet there are no Questions how intricate soever they may be by the equivocal Terms of the Senses but Aristotle and most part of other Philosophers pretend to resolve them in their Books without the foregoing Distinctions and without considering that they are equivocal by Errour and Ignorance If for example those Persons who have employed the best part of their Life in reading Ancient Philosophers and Physicians and have wholly imbib'd their Spirit and Opinions are ask'd whether Water be wet whether Fire be dry Wine hot the Blood of Fishes cold Water rawer than Wine Gold perfecter than Mercury whether Plants and Beasts have Souls and a thousand like undetermin'd Questions they rashly answer by consulting only the Impressions of Objects upon their Senses or the Tracks the reading of Authors has left upon their Memory They never think those Terms are equivocal 't is a Wonder to them they should need a Definition and they cannot endure those that endeavour to let 'em understand that their Procedure is too quick and that they are seduced by their Senses and though they are never at a loss for Distinctions to perplex the most evident Things yet in these Questions in which Equivocation needs so much to be removed they find nothing to distinguish If we consider that most of the Questions of Philosophers and Physicians contain some equivocal Terms like to those that have been spoken of we shall not doubt but that those Learned Gentlemen that could not define them were unable to say any Thing solid and real in the bulky Volumes they have compos'd Which is in a manner sufficient to overthrow most of the Opinions of the Ancients It is not so with Des Cartes he perfectly knew how to distinguish those Things He ne'er resolves any Question by sensible Ideas and whoever shall be at the pains to read him shall see that he clearly evidently and almost ever demonstratively explains the chief Operations of Nature by the sole and distinct Ideas of Extension Figures and Motion The second sort of equivocal Words that is much in request amongst Philosophers contains all those general Terms of Logick by which any Thing may be easily explain'd without so much as knowing it Aristotle was the Man that made the most of it his Books are full of nothing else and some are but a mere Logick He proposes and resolves all Things by the specious Words of Genus Species Act Power Nature Form Faculty Quality Causa per se Causa per accidens His Followers can hardly understand that those Words signifie Nothing and that one is not more learned than he was when he has heard that Fire dissolves Metals by its dissolving Faculty that a Man digests not because his Stomach is weak or because his Concoctive Faculty does not operate as it should do I grant that those who use such general Terms and Ideas for the Explication of all Things commonly fall not into so many Errours as those that only employ such Words as raise the confused Ideas of the Senses The School-Philosophers are not so liable to be deceived as some opinionative and dogmatical Physicians who build Systems upon Experiments the Reasons of which are unknown to them because the School-men talk so generally that they do not venture much out of their Depth Fire heats dries hardens and softens because it has the Faculty of producing those Effects Sena purges by its purgative Quality Bread nourishes by its nutritious Quality These Propositions are not liable to mistake for a Quality is that which denominates a Thing by such a Name Master Aristotle's Definition is undeniable But he speaks true only because he says nothing and if his rambling
them together In a word as it does nothing it must needs congregate nothing Aristotle judging of things by his Senses imagin'd Cold to be as positive as Heat and because the Sensations of Heat and Cold are both real and positive he supposes them both likewise to be active Qualities and indeed if we follow the Impressions of the Senses we shall be apt to believe that Cold is a very active Quality since 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 those Metals be yet strong enough to separate the Parts of the Bodies which they touch 'T is plain by what has been said in the First Book concerning the Errours of the Senses That if we relye upon the Judgment the Senses make of the Qualities of sensible Bodies 't is impossible to discover any certain and undeniable Truth that may serve as a Principle to proceed in the Knowledge of Nature For one cannot so much as discover that way what things are hot and what cold amongst several Persons who touch luke-warm Water it feels cold to those that are hot and hot to those that are cold And if we suppose Fishes susceptible of Sensation 't is very probable that they feel it warm when all or most Men feel it cold It is the same with Air that seems to be hot or cold according to the different Dispositions of the Bodies of those that are exposed to it Aristotle pretends that it is hot but I fansie that the Nothern Inhabitants are of another Opinion since several learned Men whose Climate is as hot as that of Greece have asserted it to be cold But that Question which has made so much noise in the Schools will never be resolv'd as long as no distinct Idea shall be affixed to the Word Heat The Definitions Aristotle lays down of Heat and Cold cannot settle that Idea For Instance Air and even Water though never so hot and scalding congregate the parts of melted Lead together with those of any other Metal whatsoever Air conglutinates all sorts of Fat joyn'd with Gums or any other solid Bodies And he shall be a very formal Peripatetick who should think of exposing Mastich to the Air to separate the pitchy from the Earthy part and other compound Bodies to uncompound them And therefore Air is not hot according to the Definition which Aristotle gives of Heat Air separates Liquors from the Bodies that are imbued with them hardens Clay dries spread Linen though Aristotle makes it moist and so is hot and drying according to the same Definition therefore it cannot be determined by that Definition whether or no Air is hot It may indeed be asserted that Air is hot in reference to Clay since it separates the Water from the Earthy Part. But must we try all the various Effects of Air upon all Bodies before we can be assured whether there is Heat in the Air we breath in If it be so we shall never be sure of it and 't is as good not to philosophize at all upon the Air we respire but upon some certain pure and elementary Air not to be found here below of which we can very dogmatically assert with Aristotle that it is hot without giving the least Proof of it nor even distinctly knowing what we understand either by that Air or by the Heat ascribed to it For thus we shall lay down Principles scarce to be destroyed not because of their Plainness and Certainty but by reason of their Darkness and their being like to Apparitions which cannot be wounded because they have not a Body I shall not insist upon Aristotle's Definitions of Moisture and Dryness it being evident that they explain not their Nature For according to those Definitions Fire is not dry since it is not easily contained within its own limits and Ice is not moist since it keeps within its proper Bounds and can difficultly be adapted to external Bounds But if fluid be understood by the Word humid or moist it may again be said that Ice is not moist and that Flame melted Gold and Lead are very humid If by humid or moist be understood what easily cleaves to any thing Ice is not humid and Pitch Fat and Oil are moister than Water since they cleave to Bodies more strongly than it does Quick-silver is moist in that sense for it cleaves to Metals whereas Water is not perfectly moist since it cleaves not to most of them So that 't is unserviceable to have recourse to the Testimony of the Senses to defend the Opinions of Aristotle But without farther examining his wonderful Definitions of the four Elementary Qualities let us suppose that whatever the Senses teach us of those Qualities is incontestable let us muster up all our Faith and believe all those Definitions very accurate Only let it be allowed us to enquire whether all the Qualities of sensible Bodies are made of these Elementary Qualities Aristotle pretends it and he must do so indeed since he looks upon those Four primitive Qualities as the Principles of all the things which he intends to explain in his Books of Physicks He teaches us that Colours are produced from the Mixture of those Four Elementary Qualities White is produced when Moisture exceeds Heat as in old Men when they grow gray Black when Moisture is exhausted as in the Walls of Cisterns and all other Colours by the like Mixtures that Odours and Savours arise from different Degrees of Dryness and Moisture mix'd together by Heat and Cold and that even Gravity and Levity do depend thereon In short All sensible Qualities must needs be produced according to Aristotle by Two active Principles viz. Heat and Cold and composed of Two passive namely Dryness and Moisture that there may be some probable Connexion betwixt his Principles and the Consequences he draws from them However 't is yet a harder Task to persuade us of such things than any of those that have been hitherto related from Aristotle We can scarce believe that the Earth and other Elements would not be colour'd or visible if they were in their natural Purity without Mixture of those Elementary Principles though some learned Commentators on that Philosopher assert it We understand not what Aristotle means when he assures us that gray Hair is produced by Moisture because in old Men Moisture exceeds Heat though to illustrate his thought we put the definition instead of the thing defined For it looks like an incomprehensible piece of Nonsence to say that the Hair of old Men becomes gray because what is not easily contained within its own Limits 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 saying it consists in a mixture of Dryness Moisture and of Heat especially when we put instead of those words the Definitions given by that Philosopher as it would prove useful
same blow produces very different motions and consequently excites very different Sensations in a Man of a Robust Constitution and in a Child or a Woman of a tender make Thus since we cannot be ascertain'd that there are two Persons in the World who have the Organs of their Senses exactly match'd we cannot be assur'd there are two Persons in the World who have altogether the same Sensations of the same Objects This is the Original cause of the strange Variety which is found in the Inclinations of Men. Some there are who are extremely pleas'd with Musick others find nothing agreeable in it And even between these who delight in it some one sort of Musick some another according to that almost Infinite Diversity which is found in the Fibres of the Auditory Nerve in the Blood and the Animal Spirits How great for instance is the difference between the Musick of Italy of France of the Chinese and other People and consequently between the Relish these different People have of these different sorts of Musick It is usual likewise for the same Men at several times to receive different Impressions from the same Consorts For if the Imagination be well warm'd by a great plenty of brisk and active Spirits a Man is much more pleas'd with a bolder Hand or a Voluntarie wherein there are many Discords than with a softer Musick that is compos'd with exacter Rules and a Mathematical Niceness Experience proves this and 't is easie to give a Reason for it 'T is just the same with Smells He that loves an Orange-flower possibly cannot endure a Rose and so on the contrary As for Tasts there is no less a Diversity in them than in the other Sensations Sawces must be made wholly different equally to please different Men or equally to please the same Person at different times One loves Sweet another Sowre One loves the Taste of Wine another abhors it the same Person who thinks it pleasant when he 's in Health finds it bitter in a Fever and so 't is with the other Senses And yet all Men are fond of Pleasure they all delight in agreeable Sensations And in this have all the same Inclinations They receive not therefore the same Sensations from the same Objects since they do not love them equally alike Thus that which makes one Man say he likes sweet things is the agreeable Sensation he has of them and that which makes another say he does not love sweet things is indeed because he has a different Sensation from him that loves them And so in saying he loves not sweet things it is not imply'd that he would not have the same Sensation as the other but only that he has it not Wherefore 't is an Impropriety of Speech for a Man to say he loves not what is Sweet he should say he loves not Sugar or Honey or the like which to others seem sweet and agreeable and that he has not the same Taste as others because the Fibres of his Tongue are differently dispos'd But to give a sensible Instance Let us suppose that among twenty Men there were some one of them whose Hands were Cold and that he was unacquainted with the words they make use of in England to explain the Sensation of Heat and Cold by and on the contrary that the Hands of all the rest were extreamly Hot. If in Winter some Water somewhat frigid should be brought them all to wash in those whose Hands were very Hot washing after each other might very well say This Water is very Cold I can't endure it But when the other whose Hands were extreamly Cold came to wash at last he might say on the contrary I can't imagine Gentlemen why ye like not the Cold Water for my part I take pleasure in feeling it Cold and washing in it It is manifest in this particular instance That the last in saying he lov'd the Cold could mean nothing else but that he lov'd the Heat and that he felt the Water Hot whilst others felt the contrary Thus when a Man says I love what is bitter and can't endure sweets no more is meant thereby than that he has not the same Sensations as those who say they love sweets and have an aversion to what is bitter It is certain therefore that a Sensation which is agreeable to one Man is so to all others who have the same but the same Objects does not cause the same Sensation in all Men because of the different disposition of the Organs of the Senses which is a thing of greatest consequence to be observ'd both as to Natural and Moral Philosophy To this only one Objection can be made and that very easie to be answer'd which is this It sometimes happens that those very Persons who love extreamly some sorts of Meat at length shall hate them in as great a degree either because in eating they met with some uncleanliness in the Dish which surpriz'd and disgusted them or because they surfeited on them by eating to excess or for several other reasons These Men 't is objected love not the same Sensations as they lov'd before For still though they eat the same Meats yet they find them no longer pleasant and palatable In answering this Objection it must be observ'd that these Men upon eating those Meats to which they have so great an abhorrence and loathing have two very different Sensations at the same time They have that of the Meat which they eat as 't is suppos'd in the Objection And they have yet another Sensation of Distaste or Loathing which proceeds for instance from a strong imagination of some uncleanliness they have formerly seen mingled with what they eat The reason of this is that when two Motions are occasion'd in the Brain at the same time one of them is never excited without the other unless it be some considerable time after Thus because the Agreeable is always accompany'd with the Loathsome Sensation and we usually confound things which happen at the same time we imagine with our selves that this Sensation which was formerly pleasant and agreeable is no longer so And yet if it were always the same it must necessarily be always agreeable Wherefore supposing it to be disagreeable and unpleasant 't is because it is joyn'd and confounded with another Sensation which is more distastful than it is it self agreeable There is much more difficulty to prove that Colours and such other Sensations which I term'd the Faint and Languid are not the same in all Mankind Because all these Sensations affect the Soul so weakly that a Man cannot distinguish as he may in Tasts or other more powerful and lively Sensations whether one is more agreeable than another nor discover the diversity of Mens Sensations by the variety of Pleasure or Distast which might be found in different Persons Yet Reason which shews that the other Sensations are not all alike in different Persons does likewise shew there must necessarily be variety in
and Reproofs of our internal Master that Answers our Questions that is the Application of our Mind and the Desires of our Heart Then will that Truth serve as an infallible Principle to proceed in the Acquisition of Sciences All the Rules we have given are not necessary in all sorts of Questions for the first Rule is sufficient in those that are easie and we need but in some others the first and second In short since we must make use of those Rules 'till we have discover'd the Truth we seek for it follows that the more difficult the Questions are the greater must the number of those Rules be which we must put in practice Those Rules are not very numerous but very natural as depending upon each other and may be made so familiar as to fall of themselves into the Mind as often as shall be requisite In short they can rule the Attention of the Mind without dividing it which is in great part what we could desire but they look so inconsiderable in themselves that to make them more recommendable it is necessary to shew that the Philosophers are fallen into a great many Errours and Extravagancies by not observing so much as the two first which are the chief and easiest of all whereas Des Cartes by their use has discover'd all those great and fruitful Truths which are to be learn'd in his Works CHAP. II. Of the general Rule that concerns the Subject of our Studies That School-Philosophers observe it not which is the Cause of several Errours in their Physicks THE first of these Rules and which respects the Subject of our Studies teaches that we must not argue except from clear Ideas whence it follows that to study methodically we must begin with things most simple and easie to be understood and insist long upon them before we undertake to enquire after the more composed and difficult Every one will easily grant the necessity of that general Rule plainly seeing that he walks in the dark who reasons upon obscure Ideas and uncertain Principles But 't will be matter of surprize to hear us affirm that it is hardly ever observed and that the greatest part of those Sciences which still at this day flush the Pride of some false Pretenders to Science are only grounded upon such Ideas as are either too confused or too general to be conducible to the finding out of Truth Aristotle who so justly deserves the Quality of Prince of such Philosophers as being the Father of that Philosophy which they so studiously cultivate reasons very seldom upon other Ideas than such as are confused and sensible and upon others that are general undetermin'd and representing nothing particular to the Mind For the ordinary Expressions of that Philosopher are so perplexed as to represent only to the Senses and Imagination the confused Sentiments we have of sensible things or to make his Disciples speak in such a rambling and indeterminate manner as not to understand themselves Most of his Works but especially his Eight Books of Physicks on which are as many different Commentators as there are Professors of Philosophy are a mere Logical Tattle where he talks much and says nothing Not that his Stile is too copious and diffused but because he has a particular Talent at being succinct and saying nothing but Words In his other Works he makes not such frequent use of his loose and general Terms but those he employs raise only the confused Ideas of the Senses by which Ideas he pretends in his Problems and elsewhere to resolve in two Words an infinite Number of Questions of which it may be demonstrated that they are altogether insoluble But that my Meaning may be better understood what I have proved in other Places must here be remembred viz. That all the Terms that excite nothing but sensible Ideas are equivocal nay and what 's to be well observ'd Equivocal from Errour and Ignorance which must needs cause an infinite number of Delusions The Word Ram is equivocal signifying an Animal that ruminates and a Constellation into which the Sun enters at Spring but that seldom causes any Mistake For he must be an Astrologer with a Witness who should imagine any Relation betwixt those two Things and believe for instance that we are subject at that time to vomit up the Medicines that we take because the Ram is a ruminating Beast But as to the Terms of sensible Ideas but few acknowledge them for Equivocal Aristotle and the Ancient Philosophers did not so much as dream on 't which will be agreed to by any one that has read any of their Books and distinctly knows the Cause why those Words are liable to Equivocation For nothing is more evident than that the Philosophers Opinion as to that Matter was quite contrary to the Truth For instance When they say that Fire is hot Grass green Sugar sweet they understand just as Children and the vulgar of Men that Fire contains in it what they feel when they warm themselves that Grass has painted upon it the Colours they see that Sugar is endued with that Sweetness they taste when they eat it and so as to all other visible and sensible Qualities which cannot be denied by those that have read their Writings They talk of sensible Qualities as of Sensations they take Heat for Motion And thus by the Equivocation of Terms they confound the Modes of Existence peculiar to Bodies with the Modifications of the Soul 'T is no longer since than Des Cartes's time that to those confused and indeterminate Questions Whether Fire is hot Grass green and Sugar sweet c. we use to answer by distinguishing the Equivocation of sensible Terms that express them If by Heat Colour and Savour you understand such and such Dispositions of Parts or Motion of insensible Particles then Fire is hot Grass green and Sugar sweet But if by Heat and other Qualities you understand what I feel when near the Fire what I see when I see Grass c. Fire is not hot nor Grass green c. For the Heat I feel and the Colours I see are only in the Soul as has been proved in the First Book But as Men commonly suppose that what they feel is the same with that which is in the Object so they believe they are in the right when they judge of the Qualities of Objects by their own Sensations And thus they hardly say two Words without speaking a Falsehood and never say any thing upon that Matter but what is obscure and confused and that for the several following Reasons First Because all Men have not the same Sensations of the same Objects nor even the same Man in different Times or when different Parts of his Body are affected by them What is sweet to one is bitter to another what is hot to one is cold to another what seems hot to a Man when he is cold feels cold to himself when he is hot or when other Parts of his Body are affected