Part 6

Three years have now elapsed since I finished the treatise containing all these matters; and I was beginning to revise it, with the view to put it into the hands of a printer, when I learned that persons to whom I greatly defer, and whose authority over my actions is hardly less influential than is my own reason over my thoughts, had condemned a certain doctrine in physics, published a short time previously by another individual to which I will not say that I adhered, but only that, previously to their censure I had observed in it nothing which I could imagine to be prejudicial either to religion or to the state, and nothing therefore which would have prevented me from giving expression to it in writing, if reason had persuaded me of its truth; and this led me to fear lest among my own doctrines likewise some one might be found in which I had departed from the truth, notwithstanding the great care I have always taken not to accord belief to new opinions of which I had not the most certain demonstrations, and not to give expression to aught that might tend to the hurt of any one. This has been sufficient to make me alter my purpose of publishing them; for although the reasons by which I had been induced to take this resolution were very strong, yet my inclination, which has always been hostile to writing books, enabled me immediately to discover other considerations sufficient to excuse me for not undertaking the task. And these reasons, on one side and the other, are such, that not only is it in some measure my interest here to state them, but that of the public, perhaps, to know them.

Three years have now passed since I finished the treatise covering all these matters. I was beginning to revise it for publication when I learned that people I deeply respect had condemned a certain theory in physics. Their authority over my actions is hardly less powerful than my own reason’s authority over my thoughts. Someone else had published the theory shortly before. I will not say that I accepted it. I will say only that, before their condemnation, I had seen nothing in it that I could imagine harming religion or the state. So I had seen nothing that would have kept me from presenting it in writing, if reason had convinced me of its truth. Their condemnation therefore made me fear that some of my own theories might also have strayed from the truth. Yet I have always taken great care not to accept new opinions without the most certain proofs. I have also taken great care not to express anything that might harm anyone. This fear was enough to change my decision to publish my theories. Although my reasons for deciding to publish were very strong, I have always disliked writing books. That dislike immediately helped me find other considerations sufficient to excuse me from the task. The reasons on both sides are such that explaining them here is, to some extent, in my interest. Perhaps knowing them is also in the public’s interest.

I have never made much account of what has proceeded from my own mind; and so long as I gathered no other advantage from the method I employ beyond satisfying myself on some difficulties belonging to the speculative sciences, or endeavoring to regulate my actions according to the principles it taught me, I never thought myself bound to publish anything respecting it. For in what regards manners, every one is so full of his own wisdom, that there might be found as many reformers as heads, if any were allowed to take upon themselves the task of mending them, except those whom God has constituted the supreme rulers of his people or to whom he has given sufficient grace and zeal to be prophets; and although my speculations greatly pleased myself, I believed that others had theirs, which perhaps pleased them still more. But as soon as I had acquired some general notions respecting physics, and beginning to make trial of them in various particular difficulties, had observed how far they can carry us, and how much they differ from the principles that have been employed up to the present time, I believed that I could not keep them concealed without sinning grievously against the law by which we are bound to promote, as far as in us lies, the general good of mankind. For by them I perceived it to be possible to arrive at knowledge highly useful in life; and in room of the speculative philosophy usually taught in the schools, to discover a practical, by means of which, knowing the force and action of fire, water, air the stars, the heavens, and all the other bodies that surround us, as distinctly as we know the various crafts of our artisans, we might also apply them in the same way to all the uses to which they are adapted, and thus render ourselves the lords and possessors of nature. And this is a result to be desired, not only in order to the invention of an infinity of arts, by which we might be enabled to enjoy without any trouble the fruits of the earth, and all its comforts, but also and especially for the preservation of health, which is without doubt, of all the blessings of this life, the first and fundamental one; for the mind is so intimately dependent upon the condition and relation of the organs of the body, that if any means can ever be found to render men wiser and more ingenious than hitherto, I believe that it is in medicine they must be sought for. It is true that the science of medicine, as it now exists, contains few things whose utility is very remarkable: but without any wish to depreciate it, I am confident that there is no one, even among those whose profession it is, who does not admit that all at present known in it is almost nothing in comparison of what remains to be discovered; and that we could free ourselves from an infinity of maladies of body as well as of mind, and perhaps also even from the debility of age, if we had sufficiently ample knowledge of their causes, and of all the remedies provided for us by nature. But since I designed to employ my whole life in the search after so necessary a science, and since I had fallen in with a path which seems to me such, that if any one follow it he must inevitably reach the end desired, unless he be hindered either by the shortness of life or the want of experiments, I judged that there could be no more effectual provision against these two impediments than if I were faithfully to communicate to the public all the little I might myself have found, and incite men of superior genius to strive to proceed farther, by contributing, each according to his inclination and ability, to the experiments which it would be necessary to make, and also by informing the public of all they might discover, so that, by the last beginning where those before them had left off, and thus connecting the lives and labours of many, we might collectively proceed much farther than each by himself could do.

I have never thought much of the ideas that came from my own mind. At first, my method helped me only to resolve some difficulties in the theoretical sciences to my own satisfaction. It also helped me try to guide my actions by the principles it taught me. As long as these were its only benefits, I never felt obliged to publish anything about the method. For in matters of conduct, everyone has such confidence in their own wisdom. There might be as many reformers as people if anyone were allowed to take on the task of reforming conduct. Only those whom God has made supreme rulers of his people may take on that task. So may those to whom he has given enough grace and zeal to be prophets. And although my own speculations pleased me greatly, I believed others had their own, which perhaps pleased them even more. But then I gained some general understanding of physics and began testing these ideas on various specific problems. I saw how far these ideas could take us, and how different they were from the principles used until now. I then believed that keeping these ideas hidden would gravely violate the law requiring us to promote humanity’s common good. That law binds us to do as much good as we can. For these ideas showed me that we could gain knowledge highly useful in life. We could replace the theoretical philosophy usually taught in schools with a practical philosophy. Through this practical philosophy, we could understand the powers and actions of fire, water, air, the stars, and the heavens. We could understand all the other bodies around us just as clearly as we understand the various trades of craftspeople. We could then put these bodies to every use they are suited for, just as craftspeople apply their skills. In this way, we could make ourselves masters and possessors of nature. This outcome is desirable not only because it would allow us to invent countless useful techniques. These techniques could let us enjoy the earth’s fruits and all its comforts without any effort. More importantly, this knowledge could help preserve health, undoubtedly the first and most fundamental of all this life’s blessings. For the mind depends so closely on the condition of the body’s organs and their relations to one another. If any means can ever make people wiser and more inventive than before, I believe we must seek them in medicine. It is true that medicine, as it now exists, offers few things of any remarkable usefulness. But I do not wish to belittle medicine. I am confident that everyone, even those who practice medicine, admits how little we currently know about it. Our present knowledge is almost nothing compared with what remains to be discovered. They also admit that we could free ourselves from countless illnesses of both body and mind. Perhaps we could even escape the weakness of old age. We could do so if we knew enough about their causes and all the remedies nature provides for us. But I intended to devote my whole life to pursuing this much-needed science. And I had found a path that seemed to me certain to lead anyone following it to the desired goal. Only a short life or a lack of experiments could prevent success. I therefore judged that the best way to guard against these two obstacles was to share my findings. I would faithfully make public whatever little I might discover myself. I would also encourage people of greater genius to try to go further. Each could contribute, according to their interests and abilities, to the experiments that would need to be carried out. They could also make all their discoveries public. Then those who came later could begin where their predecessors had stopped. By joining the lives and work of many people, we could collectively go much further than anyone could alone.

I remarked, moreover, with respect to experiments, that they become always more necessary the more one is advanced in knowledge; for, at the commencement, it is better to make use only of what is spontaneously presented to our senses, and of which we cannot remain ignorant, provided we bestow on it any reflection, however slight, than to concern ourselves about more uncommon and recondite phenomena: the reason of which is, that the more uncommon often only mislead us so long as the causes of the more ordinary are still unknown; and the circumstances upon which they depend are almost always so special and minute as to be highly difficult to detect. But in this I have adopted the following order: first, I have essayed to find in general the principles, or first causes of all that is or can be in the world, without taking into consideration for this end anything but God himself who has created it, and without educing them from any other source than from certain germs of truths naturally existing in our minds In the second place, I examined what were the first and most ordinary effects that could be deduced from these causes; and it appears to me that, in this way, I have found heavens, stars, an earth, and even on the earth water, air, fire, minerals, and some other things of this kind, which of all others are the most common and simple, and hence the easiest to know. Afterwards when I wished to descend to the more particular, so many diverse objects presented themselves to me, that I believed it to be impossible for the human mind to distinguish the forms or species of bodies that are upon the earth, from an infinity of others which might have been, if it had pleased God to place them there, or consequently to apply them to our use, unless we rise to causes through their effects, and avail ourselves of many particular experiments. Thereupon, turning over in my mind I the objects that had ever been presented to my senses I freely venture to state that I have never observed any which I could not satisfactorily explain by the principles had discovered. But it is necessary also to confess that the power of nature is so ample and vast, and these principles so simple and general, that I have hardly observed a single particular effect which I cannot at once recognize as capable of being deduced in man different modes from the principles, and that my greatest difficulty usually is to discover in which of these modes the effect is dependent upon them; for out of this difficulty cannot otherwise extricate myself than by again seeking certain experiments, which may be such that their result is not the same, if it is in the one of these modes at we must explain it, as it would be if it were to be explained in the other. As to what remains, I am now in a position to discern, as I think, with sufficient clearness what course must be taken to make the majority those experiments which may conduce to this end: but I perceive likewise that they are such and so numerous, that neither my hands nor my income, though it were a thousand times larger than it is, would be sufficient for them all; so that according as henceforward I shall have the means of making more or fewer experiments, I shall in the same proportion make greater or less progress in the knowledge of nature. This was what I had hoped to make known by the treatise I had written, and so clearly to exhibit the advantage that would thence accrue to the public, as to induce all who have the common good of man at heart, that is, all who are virtuous in truth, and not merely in appearance, or according to opinion, as well to communicate to me the experiments they had already made, as to assist me in those that remain to be made.

I also noticed that experiments become more necessary as our knowledge advances. At first, it is better to rely only on what our senses naturally present to us. We cannot remain unaware of these things if we give them even a little thought. This is better than studying unusual and obscure phenomena. Unusual phenomena often mislead us as long as we do not understand the causes of ordinary ones. And the conditions behind unusual phenomena are almost always so specific and subtle that they are very difficult to detect. In my own work, I have followed this order. First, I tried to find the general principles, or first causes, of everything that exists or could exist in the world. For this purpose, I considered nothing but God himself, who created the world. I drew these principles only from certain seeds of truth naturally present in our minds. Second, I examined the first and most ordinary effects that could be deduced from these causes. In this way, I seem to have found heavens, stars, an earth, and even water, air, fire, and minerals on earth. I also found some other things of this kind. These are the most common and simple things of all, and therefore the easiest to understand. Afterward, when I wanted to examine particulars, I encountered so many different objects that I reached the following conclusion. The human mind could not distinguish the forms or kinds of bodies on earth from infinitely many other possible kinds. Those other kinds might have existed here if God had chosen to place them here. Nor, consequently, could we put these bodies to use without working back from effects to causes and conducting many specific experiments. I then considered all the objects that had ever been presented to my senses. I freely venture to say that I have never observed anything I could not satisfactorily explain through the principles I discovered. But I must also admit that nature’s power is immensely vast, while these principles are very simple and general. I have hardly observed a single particular effect that I could not immediately deduce from these principles in many different ways. My greatest difficulty is usually discovering which of these ways actually accounts for the effect. I can resolve this difficulty only by seeking further experiments whose results would distinguish between the possible explanations. The result must differ depending on whether one explanation or another is correct. As for the work ahead, I think I now see clearly enough how to conduct most experiments that could serve this purpose. But I also see that the experiments are so demanding and numerous that neither my labor nor my income could cover them all. Even an income a thousand times larger than mine would not be enough. So my progress in understanding nature will depend directly on whether I have the means to conduct more or fewer experiments. I had hoped to explain this in the treatise I had written. I also hoped to show the public benefits clearly enough to encourage everyone who cares about humanity’s common good to help. By this I mean everyone who is truly virtuous, not merely virtuous in appearance or in others’ opinion. I hoped they would share the experiments they had already conducted and help me with those still to be done.

But since that time other reasons have occurred to me, by which I have been led to change my opinion, and to think that I ought indeed to go on committing to writing all the results which I deemed of any moment, as soon as I should have tested their truth, and to bestow the same care upon them as I would have done had it been my design to publish them. This course commended itself to me, as well because I thus afforded myself more ample inducement to examine them thoroughly, for doubtless that is always more narrowly scrutinized which we believe will be read by many, than that which is written merely for our private use (and frequently what has seemed to me true when I first conceived it, has appeared false when I have set about committing it to writing), as because I thus lost no opportunity of advancing the interests of the public, as far as in me lay, and since thus likewise, if my writings possess any value, those into whose hands they may fall after my death may be able to put them to what use they deem proper. But I resolved by no means to consent to their publication during my lifetime, lest either the oppositions or the controversies to which they might give rise, or even the reputation, such as it might be, which they would acquire for me, should be any occasion of my losing the time that I had set apart for my own improvement. For though it be true that every one is bound to promote to the extent of his ability the good of others, and that to be useful to no one is really to be worthless, yet it is likewise true that our cares ought to extend beyond the present, and it is good to omit doing what might perhaps bring some profit to the living, when we have in view the accomplishment of other ends that will be of much greater advantage to posterity. And in truth, I am quite willing it should be known that the little I have hitherto learned is almost nothing in comparison with that of which I am ignorant, and to the knowledge of which I do not despair of being able to attain; for it is much the same with those who gradually discover truth in the sciences, as with those who when growing rich find less difficulty in making great acquisitions, than they formerly experienced when poor in making acquisitions of much smaller amount. Or they may be compared to the commanders of armies, whose forces usually increase in proportion to their victories, and who need greater prudence to keep together the residue of their troops after a defeat than after a victory to take towns and provinces. For he truly engages in battle who endeavors to surmount all the difficulties and errors which prevent him from reaching the knowledge of truth, and he is overcome in fight who admits a false opinion touching a matter of any generality and importance, and he requires thereafter much more skill to recover his former position than to make great advances when once in possession of thoroughly ascertained principles. As for myself, if I have succeeded in discovering any truths in the sciences (and I trust that what is contained in this volume I will show that I have found some), I can declare that they are but the consequences and results of five or six principal difficulties which I have surmounted, and my encounters with which I reckoned as battles in which victory declared for me. I will not hesitate even to avow my belief that nothing further is wanting to enable me fully to realize my designs than to gain two or three similar victories; and that I am not so far advanced in years but that, according to the ordinary course of nature, I may still have sufficient leisure for this end. But I conceive myself the more bound to husband the time that remains the greater my expectation of being able to employ it aright, and I should doubtless have much to rob me of it, were I to publish the principles of my physics: for although they are almost all so evident that to assent to them no more is needed than simply to understand them, and although there is not one of them of which I do not expect to be able to give demonstration, yet, as it is impossible that they can be in accordance with all the diverse opinions of others, I foresee that I should frequently be turned aside from my grand design, on occasion of the opposition which they would be sure to awaken.

But since then, other reasons have led me to change my mind. I now think I should continue writing down all the results I consider important, once I have tested their truth. I should give these writings the same care I would give them if I intended to publish them. This approach appealed to me partly because it gave me more reason to examine my results thoroughly. We undoubtedly scrutinize writing more closely when we expect many readers than when we write only for ourselves. Often, an idea that seemed true when I first conceived it has seemed false when I began writing it down. Another reason was that I would miss no opportunity to serve the public good as far as I could. Also, if my writings have any value, whoever receives them after my death may use them as they think best. But I firmly resolved not to allow their publication during my lifetime. I feared the opposition or controversy they might provoke, or even whatever reputation they might earn me. Any of these might take away time I had set aside for my own improvement. Everyone is indeed bound to promote the good of others as far as they can. And to be useful to no one is really to be worthless. Yet our concerns should also extend beyond the present. It is good to forgo something that might perhaps benefit the living when pursuing goals of much greater benefit to posterity. Indeed, I am quite willing to acknowledge how little I have learned so far. It is almost nothing compared with what I do not know but still hope to learn. Those who gradually discover scientific truths are much like people growing rich. Such people find it easier to acquire great wealth than they once found it to acquire much smaller amounts when poor. Or these discoverers may be compared to army commanders, whose forces usually grow in proportion to their victories. After defeat, commanders need greater judgment to hold their remaining troops together than to capture towns and provinces after victory. Anyone striving to overcome the difficulties and errors that block knowledge of the truth is truly fighting a battle. Anyone accepting a false opinion on a matter of broad scope and importance suffers a defeat. Recovering their former position then requires much more skill than making great advances once they possess firmly established principles. As for me, perhaps I have succeeded in discovering some scientific truths. I trust that the contents of this volume will show that I have. If so, I can say these truths are only the consequences and results of overcoming five or six main difficulties. I counted my encounters with those difficulties as battles I had won. I will even freely admit my belief that only two or three similar victories remain before I can fully realize my plans. Nor am I so old that, in the ordinary course of nature, I may not still have enough time. But the more I expect to use my remaining time well, the greater my duty to conserve it. Publishing the principles of my physics would undoubtedly expose me to many demands on that time. Almost all these principles are so evident that simply understanding them is enough to accept them. And I expect to be able to prove every one of them. Yet these principles cannot possibly agree with all the differing opinions of others. So I foresee that the opposition they would certainly provoke would often distract me from my main goal.

It may be said, that these oppositions would be useful both in making me aware of my errors, and, if my speculations contain anything of value, in bringing others to a fuller understanding of it; and still farther, as many can see better than one, in leading others who are now beginning to avail themselves of my principles, to assist me in turn with their discoveries. But though I recognize my extreme liability to error, and scarce ever trust to the first thoughts which occur to me, yet-the experience I have had of possible objections to my views prevents me from anticipating any profit from them. For I have already had frequent proof of the judgments, as well of those I esteemed friends, as of some others to whom I thought I was an object of indifference, and even of some whose malignancy and envy would, I knew, determine them to endeavor to discover what partiality concealed from the eyes of my friends. But it has rarely happened that anything has been objected to me which I had myself altogether overlooked, unless it were something far removed from the subject: so that I have never met with a single critic of my opinions who did not appear to me either less rigorous or less equitable than myself. And further, I have never observed that any truth before unknown has been brought to light by the disputations that are practised in the schools; for while each strives for the victory, each is much more occupied in making the best of mere verisimilitude, than in weighing the reasons on both sides of the question; and those who have been long good advocates are not afterwards on that account the better judges.

Some may say that these objections would help me recognize my errors. And if my ideas contain anything valuable, objections would help others understand those ideas more fully. Moreover, since many people can see more than one, objections might encourage others now beginning to use my principles. Those people could then help me in turn with their discoveries. But I recognize how easily I can be wrong, and I hardly ever trust my first thoughts. Even so, my experience with objections to my views gives me no reason to expect any benefit from them. For I have often had the chance to test the judgments of people I considered friends. I have also tested the judgments of others who, I thought, felt neither favorably nor unfavorably toward me. I have even tested the judgments of some whose malice and envy I knew would drive them to find faults. Their aim would be to discover what my friends' partiality had hidden from them. But critics have rarely raised anything I had completely overlooked, unless the objection was far removed from the subject. So I have never encountered a critic of my views who seemed as rigorous and fair as I am. Furthermore, I have never seen the debates practiced in the schools bring any previously unknown truth to light. For each participant strives to win. Each is therefore far more concerned with making the strongest case for what merely seems true than with weighing both sides. And people who have long been skilled at arguing a case do not become better judges because of that skill.

As for the advantage that others would derive from the communication of my thoughts, it could not be very great; because I have not yet so far prosecuted them as that much does not remain to be added before they can be applied to practice. And I think I may say without vanity, that if there is any one who can carry them out that length, it must be myself rather than another: not that there may not be in the world many minds incomparably superior to mine, but because one cannot so well seize a thing and make it one’s own, when it has been learned from another, as when one has himself discovered it. And so true is this of the present subject that, though I have often explained some of my opinions to persons of much acuteness, who, whilst I was speaking, appeared to understand them very distinctly, yet, when they repeated them, I have observed that they almost always changed them to such an extent that I could no longer acknowledge them as mine. I am glad, by the way, to take this opportunity of requesting posterity never to believe on hearsay that anything has proceeded from me which has not been published by myself; and I am not at all astonished at the extravagances attributed to those ancient philosophers whose own writings we do not possess; whose thoughts, however, I do not on that account suppose to have been really absurd, seeing they were among the ablest men of their times, but only that these have been falsely represented to us. It is observable, accordingly, that scarcely in a single instance has any one of their disciples surpassed them; and I am quite sure that the most devoted of the present followers of Aristotle would think themselves happy if they had as much knowledge of nature as he possessed, were it even under the condition that they should never afterwards attain to higher. In this respect they are like the ivy which never strives to rise above the tree that sustains it, and which frequently even returns downwards when it has reached the top; for it seems to me that they also sink, in other words, render themselves less wise than they would be if they gave up study, who, not contented with knowing all that is intelligibly explained in their author, desire in addition to find in him the solution of many difficulties of which he says not a word, and never perhaps so much as thought. Their fashion of philosophizing, however, is well suited to persons whose abilities fall below mediocrity; for the obscurity of the distinctions and principles of which they make use enables them to speak of all things with as much confidence as if they really knew them, and to defend all that they say on any subject against the most subtle and skillful, without its being possible for any one to convict them of error. In this they seem to me to be like a blind man, who, in order to fight on equal terms with a person that sees, should have made him descend to the bottom of an intensely dark cave: and I may say that such persons have an interest in my refraining from publishing the principles of the philosophy of which I make use; for, since these are of a kind the simplest and most evident, I should, by publishing them, do much the same as if I were to throw open the windows, and allow the light of day to enter the cave into which the combatants had descended. But even superior men have no reason for any great anxiety to know these principles, for if what they desire is to be able to speak of all things, and to acquire a reputation for learning, they will gain their end more easily by remaining satisfied with the appearance of truth, which can be found without much difficulty in all sorts of matters, than by seeking the truth itself which unfolds itself but slowly and that only in some departments, while it obliges us, when we have to speak of others, freely to confess our ignorance. If, however, they prefer the knowledge of some few truths to the vanity of appearing ignorant of none, as such knowledge is undoubtedly much to be preferred, and, if they choose to follow a course similar to mine, they do not require for this that I should say anything more than I have already said in this discourse. For if they are capable of making greater advancement than I have made, they will much more be able of themselves to discover all that I believe myself to have found; since as I have never examined aught except in order, it is certain that what yet remains to be discovered is in itself more difficult and recondite, than that which I have already been enabled to find, and the gratification would be much less in learning it from me than in discovering it for themselves. Besides this, the habit which they will acquire, by seeking first what is easy, and then passing onward slowly and step by step to the more difficult, will benefit them more than all my instructions. Thus, in my own case, I am persuaded that if I had been taught from my youth all the truths of which I have since sought out demonstrations, and had thus learned them without labour, I should never, perhaps, have known any beyond these; at least, I should never have acquired the habit and the facility which I think I possess in always discovering new truths in proportion as I give myself to the search. And, in a single word, if there is any work in the world which cannot be so well finished by another as by him who has commenced it, it is that at which I labour.

Others would gain little from my sharing my thoughts. I have not yet developed them far enough, and much remains to be added before they can be put into practice. I think I can say without vanity that, if anyone can develop them that far, I can, rather than someone else. This is not because the world lacks minds far superior to mine. Rather, we cannot grasp an idea and make it our own as fully through learning as through discovering it ourselves. My own subject offers clear evidence of this. I have often explained some of my opinions to very perceptive people. While I was speaking, they seemed to understand those opinions very clearly. Yet when they repeated my opinions, they almost always changed them so much that I could no longer recognize them as mine. Incidentally, I welcome this chance to make a request of future generations. Never believe, on hearsay, that anything came from me unless I published it myself. Nor am I at all surprised by the outlandish ideas attributed to ancient philosophers whose own writings we lack. I do not therefore suppose their thoughts were truly absurd, since they were among the ablest people of their times. I suppose only that their thoughts have been misrepresented to us. Accordingly, hardly any of their pupils have surpassed them. I am quite sure that Aristotle’s most devoted followers today would be happy to know as much about nature as he did. They would accept even the condition that they could never gain any further knowledge. In this respect, they resemble ivy, which never tries to rise above the tree supporting it. Often, the ivy even grows downward again once it reaches the top. For it seems to me that these followers also sink, becoming less wise than if they gave up studying. They are not content to know everything their author explains clearly. They also want to find in his writings answers to many difficulties he never mentions and perhaps never even considered. Their way of philosophizing, however, is well suited to people of below-average ability. The distinctions and principles they use are so obscure that they can speak confidently about everything, as if they truly understood it. They can also defend everything they say on any subject against the sharpest and most skillful opponents. No one can prove them wrong. They seem to me like a blind man who wants to fight someone who can see on equal terms. To do so, the blind man makes his opponent descend to the bottom of a pitch-dark cave. I may say that such people have an interest in my withholding the principles of the philosophy I use. For these principles are of the simplest and most obvious kind. Publishing them would be much like opening the windows and letting daylight into the cave where the fighters had descended. But even people of superior ability have no reason to be very eager to know these principles. Suppose they want to speak about everything and gain a reputation for learning. They will achieve that goal more easily by settling for the appearance of truth than by seeking truth itself. The appearance of truth is easy enough to find in all sorts of subjects. Truth itself, however, reveals itself only slowly, and only in some fields. When we speak about other fields, truth requires us to admit our ignorance openly. They may, however, prefer knowing a few truths to the vanity of appearing ignorant of nothing. Such knowledge is undoubtedly much better. If they have that preference and choose a path like mine, they need nothing beyond what I have already said here. For if they can advance further than I have, they can all the more readily discover for themselves everything I believe I have found. I have always examined things in order. So whatever remains to be discovered is certainly more difficult and obscure than what I have already managed to find. Learning those truths from me would also be much less satisfying than discovering them independently. Besides, they will gain a useful habit by first seeking easy truths, then moving slowly, step by step, toward harder ones. That habit will benefit them more than all my instruction. In my own case, I am convinced of this. Suppose I had been taught from childhood all the truths for which I have since sought demonstrations. Had I learned them without effort, perhaps I would never have known any further truths. At least, I would never have developed the habit and ease I believe I have in discovering new truths whenever I search. In short, some work may be better completed by its original author than by anyone else. If any work in the world fits that description, it is the work I am doing.

It is true, indeed, as regards the experiments which may conduce to this end, that one man is not equal to the task of making them all; but yet he can advantageously avail himself, in this work, of no hands besides his own, unless those of artisans, or parties of the same kind, whom he could pay, and whom the hope of gain (a means of great efficacy) might stimulate to accuracy in the performance of what was prescribed to them. For as to those who, through curiosity or a desire of learning, of their own accord, perhaps, offer him their services, besides that in general their promises exceed their performance, and that they sketch out fine designs of which not one is ever realized, they will, without doubt, expect to be compensated for their trouble by the explication of some difficulties, or, at least, by compliments and useless speeches, in which he cannot spend any portion of his time without loss to himself. And as for the experiments that others have already made, even although these parties should be willing of themselves to communicate them to him (which is what those who esteem them secrets will never do), the experiments are, for the most part, accompanied with so many circumstances and superfluous elements, as to make it exceedingly difficult to disentangle the truth from its adjuncts--besides, he will find almost all of them so ill described, or even so false (because those who made them have wished to see in them only such facts as they deemed conformable to their principles), that, if in the entire number there should be some of a nature suited to his purpose, still their value could not compensate for the time what would be necessary to make the selection. So that if there existed any one whom we assuredly knew to be capable of making discoveries of the highest kind, and of the greatest possible utility to the public; and if all other men were therefore eager by all means to assist him in successfully prosecuting his designs, I do not see that they could do aught else for him beyond contributing to defray the expenses of the experiments that might be necessary; and for the rest, prevent his being deprived of his leisure by the unseasonable interruptions of any one. But besides that I neither have so high an opinion of myself as to be willing to make promise of anything extraordinary, nor feed on imaginations so vain as to fancy that the public must be much interested in my designs; I do not, on the other hand, own a soul so mean as to be capable of accepting from any one a favor of which it could be supposed that I was unworthy.

It is true that one man cannot carry out all the experiments that may help achieve this goal. Yet he can usefully rely only on his own efforts, except for help from artisans or similar workers he could pay. The hope of payment could encourage these workers to follow his instructions accurately. Such an incentive is very powerful. Others may perhaps volunteer their services out of curiosity or a desire to learn. But their promises generally exceed their performance, and they draw up grand plans, not one of which ever becomes reality. They will undoubtedly expect something in return for their trouble. They will want him to explain some difficult questions, or at least offer compliments and empty talk. He cannot spend any time on such exchanges without loss to himself. As for experiments others have already performed, their makers might willingly share them with him. Those who regard their experiments as secrets, however, will never do so. Even when shared, most experiments come with so many surrounding details and unnecessary elements that separating the truth is extremely difficult. Moreover, he will find almost all these experiments poorly described or even false. This is because the experimenters wanted to see only facts they considered consistent with their principles. So even if some experiments among the whole collection suited his purpose, their value would not justify the time spent selecting them. Suppose, then, that someone existed whom we knew for certain could make discoveries of the highest order. Suppose those discoveries could also be of the greatest possible benefit to the public. And suppose everyone else was therefore eager to help him carry out his plans successfully by every possible means. I see nothing they could do beyond helping pay for the necessary experiments. Apart from that, they could protect his free time from anyone's ill-timed interruptions. But I do not think so highly of myself that I would promise anything extraordinary. Nor do I indulge in fantasies so vain as to imagine that the public must care greatly about my plans. On the other hand, I am not so lacking in self-respect that I could accept a favor anyone might consider me unworthy of.

These considerations taken together were the reason why, for the last three years, I have been unwilling to publish the treatise I had on hand, and why I even resolved to give publicity during my life to no other that was so general, or by which the principles of my physics might be understood. But since then, two other reasons have come into operation that have determined me here to subjoin some particular specimens, and give the public some account of my doings and designs. Of these considerations, the first is, that if I failed to do so, many who were cognizant of my previous intention to publish some writings, might have imagined that the reasons which induced me to refrain from so doing, were less to my credit than they really are; for although I am not immoderately desirous of glory, or even, if I may venture so to say, although I am averse from it in so far as I deem it hostile to repose which I hold in greater account than aught else, yet, at the same time, I have never sought to conceal my actions as if they were crimes, nor made use of many precautions that I might remain unknown; and this partly because I should have thought such a course of conduct a wrong against myself, and partly because it would have occasioned me some sort of uneasiness which would again have been contrary to the perfect mental tranquillity which I court. And forasmuch as, while thus indifferent to the thought alike of fame or of forgetfulness, I have yet been unable to prevent myself from acquiring some sort of reputation, I have thought it incumbent on me to do my best to save myself at least from being ill-spoken of. The other reason that has determined me to commit to writing these specimens of philosophy is, that I am becoming daily more and more alive to the delay which my design of self-instruction suffers, for want of the infinity of experiments I require, and which it is impossible for me to make without the assistance of others: and, without flattering myself so much as to expect the public to take a large share in my interests, I am yet unwilling to be found so far wanting in the duty I owe to myself, as to give occasion to those who shall survive me to make it matter of reproach against me some day, that I might have left them many things in a much more perfect state than I have done, had I not too much neglected to make them aware of the ways in which they could have promoted the accomplishment of my designs.

Taken together, these considerations explain why, for the past three years, I have been unwilling to publish my unfinished treatise. I even decided to publish no other work during my lifetime that was so broad in scope. Nor would I publish any work that would reveal the principles of my physics. But since then, two other reasons have led me to include some specific examples here. They have also led me to give the public some account of my work and plans. The first reason concerns those who knew I had intended to publish some writings. If I published nothing, many might imagine that my reasons for holding back were less creditable than they really are. I am not excessively eager for fame. Indeed, if I may venture to say so, I dislike fame insofar as it threatens my peace. I value that peace more than anything else. Yet I have never tried to hide my actions as though they were crimes. Nor have I taken many precautions to remain unknown. Partly, I would have considered such behavior unfair to myself. Partly, it would have caused me some uneasiness, contrary to the complete peace of mind I seek. Although I am indifferent to both fame and being forgotten, I have been unable to avoid gaining some reputation. So I have felt obliged to do my best at least to avoid being spoken of badly. The other reason for writing these examples of my philosophy concerns my efforts to learn. Each day, I become more aware of how those efforts are delayed by the lack of countless experiments I need. I cannot carry out those experiments without help from others. I do not flatter myself by expecting the public to take a strong interest in my concerns. Yet I am unwilling to neglect my duty to myself so far that those who outlive me could someday reproach me. They might say I could have left them much more complete results than I did. They might blame my excessive neglect in explaining how they could have helped me carry out my plans.

And I thought that it was easy for me to select some matters which should neither be obnoxious to much controversy, nor should compel me to expound more of my principles than I desired, and which should yet be sufficient clearly to exhibit what I can or cannot accomplish in the sciences. Whether or not I have succeeded in this it is not for me to say; and I do not wish to forestall the judgments of others by speaking myself of my writings; but it will gratify me if they be examined, and, to afford the greater inducement to this I request all who may have any objections to make to them, to take the trouble of forwarding these to my publisher, who will give me notice of them, that I may endeavor to subjoin at the same time my reply; and in this way readers seeing both at once will more easily determine where the truth lies; for I do not engage in any case to make prolix replies, but only with perfect frankness to avow my errors if I am convinced of them, or if I cannot perceive them, simply to state what I think is required for defense of the matters I have written, adding thereto no explication of any new matte that it may not be necessary to pass without end from one thing to another.

And I thought I could easily choose some topics that would not invite much controversy. These topics would not force me to explain more of my principles than I wanted. Yet they would clearly show what I can and cannot accomplish in the sciences. Whether I have succeeded is not for me to say. Nor do I wish to influence others’ judgments in advance by commenting on my own writings. But I would be pleased to have my writings examined. To encourage such examination, I ask all who have objections to send them to my publisher. My publisher will notify me of these objections so that I can try to publish my replies alongside them. Readers can then see both at once and more easily judge where the truth lies. For I do not promise lengthy replies in any case. I promise only to admit my errors with complete honesty if I am convinced of them. If I cannot see those errors, I will simply state what I think is needed to defend what I have written. I will add no explanation of any new topic, so that we need not move endlessly from one subject to another.

If some of the matters of which I have spoken in the beginning of the “Dioptrics” and “Meteorics” should offend at first sight, because I call them hypotheses and seem indifferent about giving proof of them, I request a patient and attentive reading of the whole, from which I hope those hesitating will derive satisfaction; for it appears to me that the reasonings are so mutually connected in these treatises, that, as the last are demonstrated by the first which are their causes, the first are in their turn demonstrated by the last which are their effects. Nor must it be imagined that I here commit the fallacy which the logicians call a circle; for since experience renders the majority of these effects most certain, the causes from which I deduce them do not serve so much to establish their reality as to explain their existence; but on the contrary, the reality of the causes is established by the reality of the effects. Nor have I called them hypotheses with any other end in view except that it may be known that I think I am able to deduce them from those first truths which I have already expounded; and yet that I have expressly determined not to do so, to prevent a certain class of minds from thence taking occasion to build some extravagant philosophy upon what they may take to be my principles, and my being blamed for it. I refer to those who imagine that they can master in a day all that another has taken twenty years to think out, as soon as he has spoken two or three words to them on the subject; or who are the more liable to error and the less capable of perceiving truth in very proportion as they are more subtle and lively. As to the opinions which are truly and wholly mine, I offer no apology for them as new,--persuaded as I am that if their reasons be well considered they will be found to be so simple and so conformed, to common sense as to appear less extraordinary and less paradoxical than any others which can be held on the same subjects; nor do I even boast of being the earliest discoverer of any of them, but only of having adopted them, neither because they had nor because they had not been held by others, but solely because reason has convinced me of their truth.

Some points at the beginning of the “Dioptrics” and “Meteorics” may seem objectionable at first. I call them hypotheses and seem unconcerned about proving them. If these points trouble you, I ask you to read both works patiently and carefully to the end. I hope the full account will satisfy those who have doubts. For the arguments in these works seem to me so closely connected that each supports the others. The later arguments are demonstrated by the earlier ones, which identify their causes. In turn, the earlier arguments are demonstrated by the later ones, which describe their effects. But do not suppose I am committing what logicians call circular reasoning. Experience makes most of these effects quite certain. So the causes from which I deduce the effects serve less to establish their reality than to explain their existence. Conversely, the reality of the effects establishes the reality of the causes. My only purpose in calling these causes hypotheses is to make my position clear. I believe I can deduce them from the first truths I have already explained. Yet I have deliberately chosen not to make those deductions. I want to prevent certain people from building some extravagant philosophy on what they may take to be my principles. I also want to avoid being blamed for such a philosophy. I mean people who imagine they can master in a day what someone else took twenty years to work out. They think they can do so after hearing just two or three words on the subject. I also mean people whose quickness and cleverness make them more prone to error and less able to recognize truth. As for the opinions that are truly and entirely mine, I make no apology for their being new. I am convinced that anyone who carefully considers the reasons behind them will find those reasons simple and sensible. My opinions will therefore seem less extraordinary and less paradoxical than any others one could hold on the same subjects. Nor do I claim to have been the first to discover any of them. I claim only to have adopted them solely because reason convinced me they were true. I did not adopt them because others had held them, or because others had not.

Though artisans may not be able at once to execute the invention which is explained in the “Dioptrics,” I do not think that any one on that account is entitled to condemn it; for since address and practice are required in order so to make and adjust the machines described by me as not to overlook the smallest particular, I should not be less astonished if they succeeded on the first attempt than if a person were in one day to become an accomplished performer on the guitar, by merely having excellent sheets of music set up before him. And if I write in French, which is the language of my country, in preference to Latin, which is that of my preceptors, it is because I expect that those who make use of their unprejudiced natural reason will be better judges of my opinions than those who give heed to the writings of the ancients only; and as for those who unite good sense with habits of study, whom alone I desire for judges, they will not, I feel assured, be so partial to Latin as to refuse to listen to my reasonings merely because I expound them in the vulgar tongue.

Although craftspeople may not immediately be able to build the invention explained in the “Dioptrics,” that does not justify condemning it. Building and adjusting the machines I describe requires skill and practice, so that even the smallest detail is not overlooked. I would be no less astonished if craftspeople succeeded on their first attempt than if someone mastered the guitar in one day simply by having excellent sheet music placed before them. And if I write in French, my country's language, rather than Latin, my teachers' language, I have a reason. I expect people who use their natural reason without prejudice to judge my views better than those who heed only ancient writings. The only judges I want are people who combine good sense with a habit of study. I am sure they will not favor Latin so strongly that they refuse to consider my arguments simply because I present them in the everyday language.

In conclusion, I am unwilling here to say anything very specific of the progress which I expect to make for the future in the sciences, or to bind myself to the public by any promise which I am not certain of being able to fulfill; but this only will I say, that I have resolved to devote what time I may still have to live to no other occupation than that of endeavoring to acquire some knowledge of Nature, which shall be of such a kind as to enable us therefrom to deduce rules in medicine of greater certainty than those at present in use; and that my inclination is so much opposed to all other pursuits, especially to such as cannot be useful to some without being hurtful to others, that if, by any circumstances, I had been constrained to engage in such, I do not believe that I should have been able to succeed. Of this I here make a public declaration, though well aware that it cannot serve to procure for me any consideration in the world, which, however, I do not in the least affect; and I shall always hold myself more obliged to those through whose favor I am permitted to enjoy my retirement without interruption than to any who might offer me the highest earthly preferments.

In conclusion, I do not wish to say anything very specific about the scientific progress I expect to make. Nor do I wish to make any public promise I am not certain I can keep. But I will say only this: I have decided to spend whatever time I have left solely studying Nature. I will seek knowledge that will allow us to derive more reliable rules for medicine than those now used. I am deeply opposed to all other pursuits, especially those that benefit some only by harming others. If circumstances had forced me into such pursuits, I do not believe I could have succeeded. I make this declaration publicly, though I know it cannot earn me any standing in the world. Yet I have no desire at all for such standing. I will always feel more indebted to those whose kindness allows me to live in uninterrupted seclusion. My debt to them will exceed any I might owe to those offering me the highest worldly positions.