A Discourse of a Method for the Well Guiding of Reason and the Discovery of Truth in the Sciences

But there are divers other things which witness, that the true cause of this motion of the bloud is that which I have related. As first, The difference observed between that which issues out of the veins, and that which comes out of the arteries, cannot proceed but from its being rarified and (as it were) distilled by passing thorow the heart: its more subtil, more lively, and more hot presently after it comes out; that is to say, being in the arteries, then it is a little before it enters them, that is to say, in the veins. And if you observe, you will finde, that this difference appears not well but about the heart; and not so much in those places which are farther off. Next, the hardnesse of the skin of which the artery vein and the great artery are composed, sheweth sufficiently, that the bloud beats against them more forcibly then against the veins. And why should the left concavity of the heart, and the great artery be more large and ample then the right concavity, and the arterious vein; unless it were that the bloud of the veinous artery, having bin but onely in the lungs since its passage thorow the heart, is more subtil, and is rarified with more force and ease then the bloud which immediately comes from the vena cava. And what can the Physicians divine by feeling of the pulse, unlesse they know, that according as the bloud changeth its nature, it may by the heat of the heart be rarified to be more or lesse strong, and more or lesse quick then before. And if we examine how this heat is communicated to the other members, must we not avow that ’tis by means of the bloud, which passing the heart, reheats it self there, and thence disperseth it self thorow the whole body: whence it happens, that if you take away the bloud from any part, the heat by the same means also is taken a way. And although the heart were as burning as hot iron, it were not sufficient to warm the feet and the hands so often as it doth, did it not continue to furnish them with new bloud.

Besides, from thence we know also that the true use of respiration is to bring fresh air enough to the lungs, to cause that bloud which comes from the right concavity of the heart, where it was rarified, and (as it were) chang’d into vapours, there to thicken, and convert it self into bloud again, before it fall again into the left, without which it would not be fit to serve for the nourishment of the fire which is there. Which is confirm’d, for that its seen, that animals which have no lungs have but one onely concavity in the heart; and that children, who can make no use of them when they are in their mothers bellies, have an opening, by which the bloud of the vena cava runs to the left concavity of the heart, and a conduit by which it comes from the arterious vein into the great artery without passing the lungs.

Next, How would the concoction be made in the stomach, unlesse the heart sent heat by the arteries, and therewithall some of the most fluid parts of the bloud, which help to dissolve the meat receiv’d therein? and is not the act which converts the juice of these meats into bloud easie to be known, if we consider, that it is distill’d by passing and repassing the heart, perhaps more then one or two hundred times a day? And what need we ought else to explain the nutrition and the production of divers humours which are in the body, but to say, that the force wherewith the bloud in rarifying it self, passeth from the heart towards the extremities or the arteries, causeth some of its parts to stay amongst those of the members where they are, and there take the place of some others, which they drive from thence? And that according to the situation, or the figure, or the smalnesse of the pores which they meet, some arrive sooner in one place then others. In the same manner as we may have seen in severall sieves, which being diversly pierc’d, serve to sever divers grains one from the other. And briefly, that which is most remarkable herein, is the generation of the animal spirits, which are as a most subtil wind, or rather, as a most pure and lively flame, which continually rising in great abundance from the heart to the brain, dischargeth it self thence by the nerves into the muscles, and gives motion to all the members; without imagining any other reason which might cause these parts of the bloud, which being most mov’d, and the most penetrating, are the most fit to form these spirits, tend rather towards the brain, then to any other part. Save onely that the arteries which carry them thither, are those which come from the heart in the most direct line of all: And that according to the rules of the Mechanicks, which are the same with those of Nature, when divers things together strive to move one way, where there is not room enough for all; so those parts of bloud which issue from the left concavity of the heart tend towards the brain, the weaker and less agitated are expell’d by the stronger, who by that means arrive there alone.

I had particularly enough expounded all these things in a Treatise which I formerly had design’d to publish: In pursuit whereof, I had therein shewed what ought to be the fabrick of the nerves and muscles of an humane body, to cause those animall spirits which were in them, to have the power to move those members. As we see that heads a while after they are cut off, yet move of themselves, and bite the ground, although they are not then animated. What changes ought to be made in the brain to cause waking, sleeping, and dreaming: how light, sounds, smels, tasts, heat, and all other qualities of exteriour objects, might imprint severall Ideas by means of the senses. How hunger and thirst, and the other interiour passions might also send theirs thither. What ought to be taken therein for common sense, where these Ideas are received; for memory which preserves them; and for fancy, which can diversly change them, and form new ones of them; and by the same means, distributing the animal spirits into the muscles, make the members of the body move in so many severall fashions, and as fitly to those objects which present themselves to its senses; and to the interiour passions which are in them, as ours may move themselves without the consent of the Wil. Which wil seem nothing strange to those, who knowing how many Automatas or moving Machines the industry of men can make, imploying but very few pieces, in comparison of the great abundance of bones, muscles, nerves, arteries, veins, and all the other parts which are in the body of every Animal, will consider this body as a fabrick, which having been made by the hands of God, is incomparably better ordered, and hath more admirable motions in it then any of those which can be invented by men. And herein I particularly insisted, to make it appear, that if there were such Machines which had organs, and the exteriour figure of an Ape, or of any other unreasonable creature, we should finde no means of knowing them not to be altogether of the same nature as those Animals: whereas, if there were any which resembled our bodies, and imitated our actions as much as morally it were possible, we should always have two most certain ways to know, that for all that they were not reall men: The first of which is, that they could never have the use of speech, nor of other signes in framing it, as we have, to declare our thoughts to others: for we may well conceive, that a Machine may be so made, that it may utter words, and even some proper to the corporal actions, which may cause some change in its organs; as if we touch it in some part, and it should ask what we would say; or so as it might cry out that one hurts it, and the like: but not that they can diversifie them to answer sensibly to all what shall be spoken in its presence, as the dullest men may do. And the second is, That although they did divers things aswel, or perhaps better, then any of us, they must infallibly fail in some others, whereby we might discover that they act not with knowledge, but onely by the disposition of their organs: for whereas Reason is an universal instrument which may serve in all kinde of encounters, these organs have need of some particular disposition for every particular action: whence it is, that its morally impossible for one Machine to have severall organs enough to make it move in all the occurrences of this life, in the same manner as our Reason makes us move. Now by these two means we may also know the difference which is between Men and Beasts: For ’tis a very remarkable thing, that there are no men so dull and so stupid, without excepting those who are out of their wits, but are capable to rank severall words together, and of them to compose a Discourse, by which they make known their thoughts: and that on the contrary, there is no other creature, how perfect or happily soever brought forth, which can do the like. The which happens, not because they want organs; for we know, that Pyes and Parrots can utter words even as we can, and yet cannot speak like us; that is to say, with evidence that they think what they say. Whereas Men, being born deaf and dumb, and deprived of those organs which seem to make others speak, as much or more then beasts, usually invent of themselves to be understood by those, who commonly being with them, have the leisure to learn their expressions. And this not onely witnesseth, that Beasts have lesse reason than men, but that they have none at all. For we see there needs not much to learn to speak: and forasmuch as we observe inequality amongst Beasts of the same kind, aswell as amongst men, and that some are more easily managed then others; ’tis not to be believed, but that an Ape or a Parrot which were the most perfect of its kinde, should therein equall the most stupid child, or at least a child of a distracted brain, if their souls were not of a nature wholly different from ours. And we ought not to confound words with naturall motions, which witness passions, and may be imitated by Machines aswell as by Animals; nor think (as some of the Ancients) that beasts speak, although we do not understand their language: for if it were true, since they have divers organs which relate to ours, they could aswell make themselves understood by us, as by their like. Its likewise very remarkable that although there are divers creatures which express more industry then we in some one of their actions; yet we may well perceive, that the same shew none at all in many others: So that what they do better then we, proves not at all that they have reason; for by that reckoning they would have more then any of us, and would do better in all other things; but rather, that they have none at all, and that its Nature onely which works in them according to the disposition of their organs. As wee see a Clock, which is onely composed of wheels and springs, can reckon the hours, and measure the times more exactly then we can with all our prudence.

After this I had described the reasonable Soul, and made it appear, that it could no way be drawn from the power of the Matter, as other things whereof I had spoken; but that it ought to have been expresly created: And how it suffiseth not for it to be lodg’d in our humane body as a Pilot in his ship, to move its members onely; but also that its necessary it be joyned and united more strongly therewith to have thoughts and appetites like ours, and so make a reall man.

I have here dilated my self a little on the subject of the Soul, by reason ’tis of most importance; for, next the errour of those who deny God, which I think I have already sufficiently confuted, there is none which sooner estrangeth feeble minds from the right way of vertue, then to imagine that the soul of beasts is of the same nature as ours, and that consequently we have nothing to fear nor hope after this life, no more then flies or ants. Whereas, when we know how different they are, we comprehend much better the reasons which prove that ours is of a nature wholly independing from the body, and consequently that it is not subject to die with it. And that when we see no other cause which destroys it, we are naturally thence moved to judge that it’s immortall.

PART. VI

Its now three years since I ended the Treatise which contains all these things, and that I began to review it, to send it afterwards to the Presse, when I understood, that persons to whom I submit, and whose authority can no lesse command my actions, then my own Reason doth my thoughts, had disapproved an opinion in Physicks, published a little before by another; of which I will not say that I was, but that indeed I had observed nothing therein, before their censure, which I could have imagined prejudiciall either to Religion or the State; or consequently, which might have hindred me from writing the same, had my Reason perswaded mee thereto. And this made me fear, lest in the same manner there might be found some one amongst mine, in which I might have been mistaken; notwithstanding the great care I always had to admit no new ones into my belief, of which I had not most certain demonstrations; and not to write such as might turn to the disadvantage of any body. Which was sufficient to oblige me to change my resolution of publishing them. For although the reasons for which I had first of all taken it, were very strong; yet my inclination, which alwayes made me hate the trade of Book-making, presently found me out others enough to excuse my self from it. And these reasons on the one and other side are such, that I am not only somewhat concern’d to speak them; but happily the Publick also to know them.

I never did much esteem those things which proceeded from mine own brain; and so long as I have gathered no other fruits from the Method I use, but onely that I have satisfied my self in some difficulties which belong to speculative Sciences, or at least endeavoured to regulate my Manners by the reasons it taught me, I thought my self not obliged to write any thing of them. For, as for what concerns Manners, every one abounds so much in his own sense, That we may finde as many Reformers as heads, were it permitted to others, besides those whom God hath established as Soveraigns over his people, or at least, to whom he hath dispensed grace and zeal enough to be Prophets, to undertake the change of any thing therein. And although my Speculations did very much please me, I did beleeve that other men also had some, which perhaps pleas’d them more. But as soon as I had acquired some generall notions touching naturall Philosophy, and beginning to prove them in divers particular difficulties, I observed how far they might lead a man, and how far different they were from the principles which to this day are in use; I judg’d, that I could not keep them hid without highly sinning against the Law, which obligeth us to procure, as much as in us lies, the general good of all men. For they made it appear to me, that it was possible to attain to points of knowledge, which may be very profitable for this life: and that in stead of this speculative Philosophy which is taught in the Schools, we might finde out a practicall one, by which knowing the force and workings of Fire, Water, Air, of the Starrs, of the Heavens, and of all other Bodies which environ us, distinctly, as we know the several trades of our Handicrafts, we might in the same manner employ them to all uses to which they are fit, and so become masters and possessours of Nature. Which is not onely to be desired for the invention of very many expedients of Arts, which without trouble might make us enjoy the fruits of the earth, and all the conveniences which are to be found therein: But chiefly also for the preservation of health, which (without doubt) is the first good, and the foundation of all other good things in this life. For even the minde depends so much on the temper and disposition of the organs of the body, that if it be possible to finde any way of making men in the generall wiser, and more able then formerly they were, I beleeve it ought to be sought in Physick. True it is, that which is now in use contains but few things, whose benefit is very remarkable: But (without any designe of slighting of it) I assure my self, there is none, even of their own profession, but will consent, that whatsoever is known therein, is almost nothing in companion of what remains to be known. And that we might be freed from very many diseases, aswell of the body as of the mind, and even also perhaps from the weaknesses of old age, had we but knowledge enough of their Causes, and of all the Remedies wherewith Nature hath furnished us. Now having a designe to employ all my life in the enquiry of so necessary a Science; and having found a way, the following of which me thinks might infallibly lead us to it, unless we be hindred by the shortness of lifes, or by defect of experiments. I judg’d that there was no better Remedie against those two impediments, but faithfully to communicate to the publique, all that little I should discover, and to invite all good Wits to endevour to advance farther in contributing every one, according to his inclination and power, to those Experiments which are to be made, and communicating also to the publique all the things they should learn; so that the last, beginning where the precedent ended, and so joyning the lives and labors of many in one, we might all together advance further then any particular Man could do.

I also observ’d touching Experiments, that they are still so much the more necessary, as we are more advanc’d in knowledg. For in the beginning it’s better to use those only which of themselves are presented to our senses, and which we cannot be ignorant of, if we do but make the least reflections upon them, then to seek out the rarest and most studied ones. The reason whereof is, that those which are rarest, doe often deceive, when we seldome know the same of the most common ones, and that the circumstances on which they depend, are, as it were, always so particular, and so small, that it’s very uneasie to finde them out. But the order I observed herein was this. First, I endevoured to finde in generall the Principles or first Causes of whatsoever is or may be in the world, without considering any thing for this end, but God alone who created it, or drawing them elsewhere, then from certain seeds of Truth which naturally are in our souls. After this, I examined what were the first and most ordinary Effects which might be deduced from these Causes: And me thinks that thereby I found out Heavens, Starrs, an Earth; and even on the Earth, Water, Air and Fire, Minerals, and some other such like things, which are the most common, and the most simple of all, and consequently the most easie to be understood. Afterwards, when I would descend to those which were more particular, there were so many severall ones presented themselves to me, that I did beleeve it impossible for a humane understanding to distinguish the forms and species of Bodies which are on the earth, from an infinite number of others which might be there, had it been the will of God so to place them: Nor by consequence to apply them to our use, unless we set the Effects before the Causes, and make use of divers particular experiments; In relation to which, revolving in my minde all those objects which ever were presented to my senses, I dare boldly say, I observed nothing which I could not fitly enough explain by the principles I had found. But I must also confesse that the power of Nature is so ample and vast, and these principles are so simple and generall, that I can observe almost no particular Effect, but that I presently know it might be deduced from thence in many severall ways: and that commonly my greatest difficulty is to finde in which of these ways it depends thereon; for I know no other expedient for that, but again to seek some experiments, which may be such, that their event may not be the same, if it be in one of those ways which is to be exprest, as if it were in another. In fine, I am gotten so far, That (me thinks) I see well enough what course we ought to hold to make the most part of those experiments which may tend to this effect. But I also see they are such, and of so great a number, that neither my hands nor my estate (though I had a thousand times more then I have) could ever suffice for all. So that according as I shall hereafter have conveniency to make more or fewer of them, I shall also advance more or lesse in the knowledge of Nature, which I hop’d I should make known by the Treatise which I had written; and therein so clearly shew the benefit which the Publick may receive thereby, that I should oblige all those in general who desire the good of Mankinde; that is to say, all those who are indeed vertuous, (and not so seemingly, or by opinion only) aswell to communicate such experiments as they have already made, as to help me in the enquiry of those which are to be made.

But since that time, other reasons have made me alter my opinion, and think that I truly ought to continue to write of all those things which I judg’d of any importance, according as I should discover the truth of them, and take the same care, as if I were to print them; as well that I might have so much the more occasion throughly to examine them; as without doubt, we always look more narrowly to what we offer to the publick view, then to what we compose onely for our own use: and oftentimes the same things which seemed true to me when I first conceived them, appear’d afterwards false to me, when I was committing them to paper: as also that I might lose no occasion of benefiting the Publick, if I were able, and that if my Writings were of any value, those to whose hands they should come after my death, might to make what use of them they think fit.