^^^zz ^^^■^^H So, — __ _□ — — i_n o ~ -jj z , LH £ ■ o -J ====! □ CD ^"^■«" 2 — ^— -H ^^^- □ — — m ^^= CD ^^= a • i THE LIFE OF SCIENCE BOOKS IN THE LIFE OF SCIENCE LIBRARY THE LIFE OF SCIENCE Essays in the 'History of Civilization BY GEORGE SARTON VICTORY OVER PAIN A History of Anesthesia BY VICTOR ROBINSON BENJAMIN SILLIMAN Pathfinder in American Science BY JOHN F. FULTON and ELIZABETH H. THOMSON SUN, STAND THOU STILL Jhe Life and Work of Copernicus the Astronomer BY ANGUS ARMITAGE K THE LIFE OF SCIENCE • -J> <£& * Essays in the Tlistory of Civilization BY GEORGE SARTON Associate of the Carnegie Institution of Washington Professor of the History of Science, Harvard lAniversity FOREWORD BY MAX H. FISCH HENRY SCHUMAN • NEW YORK > Copyright i94 8 by "Henry Schuman, Inc. Manufactured in the V. S. A. by H. Wolff, New Jork Designed by Stefan Salter and JAaurice Xaplan FOREWORD There is in the making a movement of thought toward a new focus in the history of science. Though interrupted by two world wars and a great depression, it has been steadily taking shape and gath- ering strength. It has drawn to itself a considerable number of our more thoughtful scientists, historians, and educators. So far, it has spoken the language of scholars. In 7be Life of Science Library, it is beginning to speak the language of lay men and women, girls and boys. Among the scholars, George Sarton, who holds the chair of the History of Science at Harvard University, is respected and loved as the leader of the movement. It was he who conceived and fash- ioned its two basic tools: the Introduction to the History of Sci- ence, which he has now brought through the fourteenth century, and the journal Isis, with its systematic and critical bibliographies of current publications in the field. Dr. Sarton has not only led in developing a sound scholarly basis for the movement, but he has been the most eloquent voice of its ideals as a new form of humanism which is needed to do for our time what an older humanism did for the Renaissance. Many of the essays in which he has expressed these ideals can be read with understanding and enjoyment by the wider circle of readers for whom Ibe Life of Science Library is intended. It has seemed to the publisher and sponsors of 7be Life of Science Li- brary that its purposes could not be better conveyed than by gath- ering together in the present volume a selection from these essays. The essays chosen, though far apart in time of composition, are united by spirit and intent. They were not planned with a view to being collected here. Yet, when read together, they have vir- tues a more formal treatment would lack. By their very diversity of subject and method, they give the beginner and the layman v VI FOREWORD a livelier sense of the range of forms the history of science may take, and of the values that may be expected from it. They show by varied and lucid examples, both topical and biographical, that it is no narrow specialty but a liberating approach to human cul- ture as a whole. They are linked, moreover, by certain recurring themes: 7he unity of mankind; 7he unity of knowledge; 7he international character of science; 7he kinship of artists, saints, and scientists as fulfillers of human destiny, as creators and diffusers of spiritual values; Jhe history of art, religion, and science as the essential history of mankind, which has so far been largely "secret history" , Science as progressive in a way in which art and religion are not; 7he dependence of other forms of progress upon scientific prog- ress; 7he history of science as, therefore, the leading thread in the history of civilization, the clue to the synthesis of knowledge, the mediator between science and philosophy, and the keystone of education. The reader learns to recognize and welcome the variations on these themes. They end by becoming signposts for his own thinking. Since reading these essays in proof, I have been turning over again the pages of the thirty-eight volumes of Jsis, and re-reading Dr. Sarton's contributions to them — especially his prefaces. In an essay, 'The Faith of a Humanist/' which did duty in 1920 as preface in Volume III, he quoted a sentence from the classical scholar Gilbert Murray: "One might say roughly that material things are superseded but spiritual things not; or that everything considered as an achievement can be superseded, but considered as so much life, not." Dr. Sarton added : It is true that most men of letters, and, I am sorry to add, not a few sci- entists, know science only by its material achievements, but ignore its spirit and see neither its internal beauty nor the beauty it extracts con- tinually from the bosom of nature. Now I would say that to find in the works of science of the past, that which is not and cannot be superseded, is perhaps the most important part of our quest. A true humanist must know the life of science as he knows the life of art and the life of religion. FOREWORD VII When I suggested to my friend Henry Schuman that the phrase I have italicized be used as title for the series in which this vol- ume appears, I did not have this passage in mind, but it might well serve as a motto for the series. ni . .. t n11. . Max H. Fisch University of Illinois CONTENTS FOREWORD BY Max H. FlSCH V part one: THE SPREAD OF UNDERSTANDING 1 . The Spread of Understanding 3 2. The History of Medicine versus the History of Art 15 3. The History of Science 79 part two: SECRET HISTORY 4. Secret History 61 5. Leonardo and the Birth of Modern Science 65 6. Evariste Galois 83 7. Ernest Renan 101 8. Herbert Spencer 116 part three: EAST AND WEST 9. East and West in the History of Science 131 part four: CASTING BREAD UPON THE FACE OF THE WATERS 10. An Institute for the History of Science and Civilization 169 11. Casting Bread upon the Face of the Waters 175 EDITORIAL NOTE, ACKNOWLEDGMENTS, AND SOURCES 187 INDEX 191 63^ PART ONE THE SPREAD OF UNDERSTANDING ^»* ^ 1. THE SPREAD OF UNDERSTANDING N/u^ AR "How impatient you are!" He pats my shoulder with his heavy hand while he repeats: "How impatient you are!" But his kind eyes belie the severity of his voice and he hastens to add, as if fearing that he had been too harsh: "Of course that is just as it should be. Though they have so much more time before them, we must expect the younger people — especially full-blooded ones — to be in more of a hurry, to be less patient. It would be a sadder world if the young were tolerant. Yet, listen to me. You say the world is out of joint. I have heard that before. Has it ever been otherwise? The tree-dwellers and the cave men, I am sure, had already denounced the out-of-jointedness of their own jungle. So put it that way, if you please, but I believe it is wiser to conceive mankind as an organism, as yet undeveloped but moving steadily from chaos to order. The progress is very slow but undeniable. "And should we call it slow? How can we measure its speed? Think of it and you will realize that to speak of the slowness of evolution is nonsense. What we really mean is that our own span of life is very short. We can see but an absurdly small part of the play. How dare we criticise it, how dare we decide whether the action is slow or not? The great war was terrible enough, the wounds it made in millions of hearts may never be healed, but who can say how much of a scar it will leave on the fair face of the earth? It is considerably easier to de- stroy than to build. Why should we expect the reconstruction to be completed faster than the devastation? Why should we imagine that the world can be transformed — or improved, as you say — within our lifetime? Is that not foolish? . . . The world is not out of joint, my dear, but your telescope and your clock are out of order." Uncle Christiaan is one of the most lovable old gentlemen 3 4 THE LIFE OF SCIENCE that the generous soil of Flanders has ever produced, but as the years go by, he becomes ever more opinionated and more tyrannical. Once he is well started, I know that my chances of escaping are very small. As he had now made up his mind to prove that I was wrong to expect the world to move as if its own life were hardly longer than my own, I knew that he would not let me go on until he had labored his argument at least ten times over and I resigned myself meekly to my fate — for I love Uncle Christiaan, even if he drives me mad. And then his knowl- edge and his wisdom are very great and it is worth while to record at least the gist of what he said; but as he is hopelessly discursive and as I could not possibly reproduce the saving hu- mor of his tone, and his smiles and gestures, it will be best to tell the story in my own way. Not one story, but three stories, for the old man is nothing if not thorough. As a matter of fact he told me seven, and he would have told as many more but that I admitted he was right and promised that I would be more patient in the future. 7he Tirst Story. One of the greatest discoveries man ever made is that of our numerals, but we are so familiar with them that we take them too much for granted. Yet if you begin to think it over, is that system not very admirable which enables us not simply to write down any number very quickly and with- out ambiguity, but also to use those numbers in our computa- tions, to manipulate them according to a few fixed rules for any length of time, almost mechanically, and to obtain finally another number, written in the same short-hand, and represent- ing the very result which we had started to find out? To be sure, we might have obtained the same result by count- ing with pebbles, but that would have consumed far more time. It would have been on the whole more difficult, our chances of error greater and the errors themselves harder to detect. Our system of numerals is not so simple as it seems to be, for it involves at least three distinct ideas. To consider first the SPREAD OF UNDERSTANDING ■> most conspicuous but the least important of them, we use only ten symbols to write any number. That is, our system is decimal. The beauty of this is that the number of figures is so small. It might have been smaller still — a system of eight figures would have done very well — or else, a little larger — twelve would have made an ideal set — but not much larger without sensibly increas- ing the difficulty of computations. For in the case of a duodeci- mal system, our children would have to learn by rote their table of multiplication up to 12, and so on. Why did we choose ten? The reason is simply that our ancestors made their family ac- counts on their fingers or on their toes, and they happened to be, just like ourselves, ten-fingered and ten-toed. Ten thus be- came naturally the basis of their numeration. It is true that some other people developed other systems: the Babylonians used the basis sixty and the Mayas — most intelligent of the original Amer- icans— the basis twenty. However, the basis ten is now almost universally used, at least as far as the numbers themselves are concerned. The second idea is what we now call the principle of local value. That is the very heart of this immense discovery. When we write 324, for example, we mean to represent a collection constituted by 4 units, plus 7 tens, plus 3 hundreds. We know at once that the 3 stands for hundreds, for it is written at the third place from the right; if it were written at the seventh place, it would mean 3 millions. The third idea is, so to say, an elaboration of the second : what would one do if there were no units of a certain order? How should we write three millions and four hundreds, for example? One might leave an open space between the 4 and the 3, and another between the 3 and a final dot, but that would be very ambiguous. Some unknown genius (or, maybe, many) hit upon the device of creating a special symbol, the zero, representing no number, but to be used only to mark that units of a certain order were missing. Thus if we write 3,000,400 there can be no misunderstanding. A careful definition of the new symbol THE LIFE OF SCIENCE enabled us to use it exactly as the older ones, without further ado. It seems that the Mayas knew the use of it, but they did not think of the decimal system. When, then, did the latter, that is, the combination of the three ideas, originate? It is very probable that it originated in India sometime about the fifth or sixth century, if not earlier. The system was already known in Western Syria about 662. The Moslems who trans- mitted Greek, Hindu and Iranian knowledge to the Christian West introduced also the new numerals (which are often called Arabic numerals because of that). Yet it took the West a very long time to understand and to assimilate them. The earliest coin bearing the Hindu numerals is one with an Arabic legend struck in 1138 to commemorate the reign of Roger of Sicily. But the conditions obtaining in Sicily, where Byzantines, Latins and Moslems met on an equal footing, were too exceptional to be representative of Western Europe. However, by the end of the twelfth century a small elite was apparently familiar with the new system. Their formal and final introduction was due to Leonardo of Pisa, who published in 1202 a book containing a very clear explanation of the Hindu numerals and of the best ways of using them. Mind you, more than six centuries had already passed since this discovery and as far as Europe was concerned, this was only the beginning, the first satisfactory and successful introduction of the subject. At the close of the thirteenth century the bankers of Florence were forbidden to use these numerals and we may gather that they actually used them, but in the face of a strong opposition. The only alternative was the clumsy Roman notation which offered a means of writing numbers in a manner unequiv- ocal but very unclear; it was altogether out of the question to use them for any but the very simplest reckonings. One might say that the Roman numerals could be used solely because they were not used: all calculations were actually made by some kind of abacus or calculating table, and only the results, partial or final, SPREAD OF UNDERSTANDING / were put down in Roman letters, the calculations themselves were lost in the sand or vanished with the motions of the counters. The heroic period was now long over and the rest of the history of our numerals is but one example, among so many others, of the difficulty of overcoming the enormous inertia of vested tradi- tions. The case is interesting because the new decimal system was a time- and labor-saving invention of the first magnitude. The Hindus had made to mankind a gift of inestimable value. No strings of any kind were attached to it, nor was the sug- gested improvement entangled with any sort of religious or philo- sophic ideas. Those proposing to use the new numerals were not expected to make any disavowal or concession; nor could their feelings be hurt in any way. They were asked simply to exchange a bad tool for a good one. Yet it was not until the fourteenth and fifteenth centuries that the new system was generally accepted in Italy, and not until the sixteenth and even the beginning of the seventeenth that it was finally established in the rest of civilized Europe. All counted, more than a millennium had elapsed between the discovery and its general acceptance, even in that primary stage. In the meanwhile, it is true, the center of civilization had moved from Southern Asia to Western Europe, but that had not been the cause of the delay. Mountains and seas and even desert plains are smaller obstacles to the diffusion of ideas than the unreasonable obstinacy of man. The main barriers to overcome are not out- side, but inside the brain. 7he Second Story (which is very different, and yet not so dif- ferent). It is well known that the circulation of the blood in the human body was satisfactorily explained for the first time by Wil- liam Harvey. The first idea of this discovery occurred to him not later than 1616 but he did not publish it until 1628 in a little book dealing with the motion of the heart and blood. One is rather sur- prised to find that this book did not make more stir; neither did it arouse much opposition, at least in England. In France the oppo- 8 THE LIFE OF SCIENCE sition to the new theory was considerable, but even there, and bitter as it was, it did not last very long. More happy in this than many other forerunners, Harvey was granted a taste of victory before his death in 1657. By 1673 his cause was definitely won, even in France, and the people who had been his contemporaries could witness the complete supremacy of the new doctrine. Thus less than half a century had been needed to ensure its tri- umph. The speed of this reception is less wonderful, however, than the lateness of the discovery itself, for as to Harvey's priority there can be no doubt. How is it then that no one anticipated him? There was nothing whatever in the nature of this discovery — as Harvey made it — to prevent its being made many centuries be- fore: nothing but prejudice. Until the time of Harvey, the prevalent conception was that promulgated by Galen, more than fourteen centuries earlier. It is not easy at all to give a complete account of Galen's ideas, but it will suffice to note the following points. According to him, the blood was produced in the liver from the materials furnished by our food and was then transported to the right half of the heart. Some of it passed into the left half, where it was imbued with new properties, and became fit to nourish the whole body. To use Galenic language, the blood of the right heart was endowed with "natural spirits/' that of the left heart with "vital spirits." The lat- ter blood was thus essentially different from the former. They did not circulate in the body, but both moved in a ceaseless ebb and flow, each in its own domain. But how did the blood pass from the right to the left ventricle? To explain the impossible, Galen had been obliged to assume that it passed through innumerable in- visible pores in the solid wall which divides the right heart from the left. Nobody ever detected these pores for they are not simply invisible but nonexistent. Yet Galen, supreme pontiff of Greek medicine, and nine centuries later Avicenna, the infallible medical pope of the middle ages, had spoken ex cathedra with such indis- putable authority that this gratuitous assumption was generally taken for gospel. SPREAD OF UNDERSTANDING 9 Even a man like Leonardo da Vinci, endowed with so much genius and originality, and who had himself dissected a large num- ber of bodies and examined very minutely many a heart, even he was subjugated by this intangible dogma. This is the more pa- thetic in that Leonardo was certainly on the scent of the true ex- planation, but the invisible holes were too sacred to be touched, and nothing but this prejudice caused his failure to discover and to proclaim the circulation of the blood. When I shut my eyes and evoke the past, I imagine that this great discovery was enclosed in a chest of which intelligent ob- servers like Leonardo, Vesalius, Servetus or Columbus could have easily found the secret if they had set their hearts upon it, but they did not dare approach near enough because Prejudice sat on the lid. I can see those great men standing shyly around the coffer, mysteriously attracted by it, yet awed into impotence, while Truth was prisoner inside. A moment of reflection will now convince you that the second story is not so widely different from the first as it might appear at first view. In both cases the application of a great discovery was delayed for more than a millennium by unreasonable prejudices. But in the first case the obstruction occurred after the discovery and prevented it from becoming effective, while in the second, prejudice blocked the way to the discovery itself, preventing it from being made. 7he Jhird Story (which is in some way a secjuel to the first). Prince Maurice of Nassau, stathouder of the Low Countries, took into his service about the year 1593 a Fleming of considerable genius, Simon Stevin of Bruges. He used to refer to him for mathe- matical advice and employed him as his chief hydraulic engineer and as quartermaster general of his armies. This Stevin has not yet received his full meed of recognition, for he certainly was one of the greatest men of the sixteenth century. Various important discoveries or inventions are ascribed to him and the historian of mechanics can quote no greater name for the whole interval (of 10 THE LIFE OF SCIENCE more than eighteen centuries) between Archimedes and Galileo. In the year 1585 Stevin published, in both a Dutch and French edi- tion, a little booklet entitled 7be lithe, wherein he gave for the first time a systematic account of decimal fractions. Though he was not the first to think of such fractions, he showed such a deep understanding and gave such a masterly exposition of them, that we will not be far wrong if we call him their inventor. His manner of representing them was rather clumsy, however, and that might have delayed their diffusion, had this brilliant innovation not been reinforced a little later by another invention at least equally im- portant, that of the logarithms. The logarithms, like the decimals, made it possible to increase considerably the speed of computa- tion. It has been justly said that the discovery of logarithms dou- bled the lives of the astronomers. They were introduced at the be- ginning of the following century (1614, 1619) by John Napier, laird of Merchiston, who showed us at the same time a far sim- pler method of representing the decimal fractions, the very one we use today. The triumph of the logarithms was immediate — no amount of prejudice could have prevented the astronomers from doubling their years! — and the decimals shared the triumph as a matter of course. But here again our surprise is not that these frac- tions were accepted so readily, but that they were offered so late. Indeed what did they stand for? Just as the main idea of the decimal system was to collect the objects to be counted in tens, tens of tens, or hundreds, and so on; so the gist of the decimal frac- tions was to count fragments of unity similarly in tenths, tenths of tenths or hundredths, etc. When this was consistently done it was found that those fractions could be written and used almost as simply as ordinary numbers. The decimal fractions, so to say, drove the fractions out of our calculations and the more so that one could always suppress them altogether if one wished. If it an- noyed you too much to speak of $3.53, you could say, without changing a single figure, 353 cents. The decimal fractions are so simple that most people handle them without being aware of their SPREAD OF UNDERSTANDING 11 presence, just as Monsieur Jourdain spoke in prose, without his knowing it. The most convincing proof of Stevin's genius was perhaps that after having explained the decimal fractions, he did not rest there. He saw at once the logical consequences of their introduction and the immense possibilities which were involved. Decimal numbers are naturally introduced when we enumerate objects if we count them by tens, but what will happen if our numbers are the result not of a direct enumeration, but of a mensuration — as when we want to know the length of a piece of cloth or the weight of a cheese? Then it is clear that we can only obtain the same fractions that are included in our instruments. Thus if we deal with feet and inches or shillings and pence we are driven to use duodecimal fractions which do not at all tally with our decimal system. Stevin was the first to realize that the adoption of a decimal system of numbers led irresistibly to that of a decimal system of weights and measures (and vice versa) and that neither adoption was truly complete without the other. To measure according to one system and to count according to another destroyed the economy of both. This great vision of Stevin's was beautifully simple, as simple as it was deep, yet it was not embodied until the end of the eighteenth century, when the French Revolution created the so-called metric system. The idea was accepted by the Assemblee Constituante in 1790 and the system became legally established in France. During the last century it spread all over the world, except, strangely enough, in the Anglo-Saxon countries where it met — and still meets — with a resistance, which is the stronger in that it is irra- tional. In the fifteenth century, there were still any number of learned doctors and professors who claimed that the Roman let- ters were much clearer than the Hindu numerals. Was it not much simpler to write CCCXLVIII than 348? In the same way, there are still many English and American apostles, full of learning, who will prove to everybody who will listen that their incongruous sets of weights, measures and moneys are much more convenient than 12 THE LIFE OF SCIENCE the metric system! How can they do it? I really don't know, but they do it with a fervor only equalled by the paradoxical ab- surdity of their plea. A Frenchman needs no fraction but the deci- mal,* and these can take care of themselves, so to say; he hardly notices them. On the contrary your Englishman uses vigesimal fractions if he speaks of pounds sterling and shillings; both Amer- icans and Englishmen need duodecimal fractions when dealing with feet and inches, and sixteenths to measure in pounds avoir- dupois and ounces, and many more varieties each of which seems to be entirely independent of the others. The factor ten is about the only one absent from his tables of weights and measures, yet he clings faithfully to the decimal system of numbers ! It looks as if after having admitted the superiority of these numbers, his need of order had been exhausted and he stopped short, discouraged, on the road of improvement. When Uncle Christiaan had reached this point of the story — the story which he was telling in order to instil into my soul the noble virtue of patience — he became so enraged that he could hardly master his feelings or choose his words: 'Think of it! Try to visualize this great discovery made in India about the sixth century, perfected in the Low Countries in the sixteenth, com- pleted in France at the end of the eighteenth : one of the greatest labor-saving discoveries which the human race has ever made. Can you imagine that the nations which are in many respects the most civilized of our own times have not yet grasped its importance? The work of more than ten generations has not sufficed to con- vince them with regard to a truth of the simplest and most ob- jective kind! "It makes me mad to think of the time which the children must need to become familiar with those grotesque assortments of weights and measures. As if they were not yet sufficiently handi- * Except when measuring time and angles, when he uses sexagesimal fractions, because the Babylonians wore such a deep rut with respect to these, some four thousand years ago, that mankind has not yet been able to extricate itself from it. SPREAD OF UNDERSTANDING 13 capped by the most erratic spelling of all languages dead or alive. Poor children! It did not matter so much in the past, when they had but little to learn, but now that we can not find enough time to teach them the essentials, it seems almost criminal to waste their attention upon such artificial knowledge. For even if they should know all the relations between those measures, and all the eccentricities of the English dictionary, and even, if you please, the peculiarities of many other languages, would they be able to understand the world any better? Certainly not. They might just as well have memorized the telephone directory. For example, to know that you must spell knee and pronounce nee is no real knowledge for it does not teach you anything about the nature of things in general or of knees in particular. This gives one at best a clearer notion of human perversity; it can give one no knowl- edge of nature, no understanding of the cosmos. Poor little chil- dren, victims of the insane obstinacy of their elders and of the ignorance and lack of imagination of the educators. . . ." Uncle Christiaan is so overcome that he will not talk any more. It is my turn now to soothe and humor him. Soon he will recover his enthusiasm and, maybe, his voice. To be sure, in the domain of pure science, progress has now be- come far more rapid because the value of discoveries is no longer judged by the crowds from an irrational point of view, but by ex- perts from a purely technical one. Even the most revolutionary theories, such as radioactivity, the quanta, or relativity, are exam- ined quietly by a very small body of scientists who are kept con- stantly on their guard by mutual criticism and who are expected to justify their every opinion. Their verdict, whichever it be, de- stroys any irrational obstruction in the egg. Unfortunately such improved methods can be used only in the case of problems amen- able to a scientific treatment, without any philosophic or senti- mental loophole, and which are of sufficient technicality to be beyond the reach of meddling people. In the field of technology, though so close to that of science, new ideas may be jeopardized 14 THE LIFE OF SCIENCE or their success considerably delayed, by various irrelevant cir- cumstances. This explains why the proper launching of an inven- tion is so tremendously important. But when it comes to social or political problems (not to speak of religious ones) it is almost as difficult to obtain a proper appreciation of them as it was in the middle ages. Indeed a large number of the non- or half-educated people, even of the most enlightened nations, are still intellectually in the medieval stage. That is, they are uncritical, unable to judge matters dispassionately, unable to disentangle truth from its web of prejudice. We should not, in our turn, judge them too severely, for even the greatest heroes of truth were not entirely untram- melled. It humbles our minds but mollifies our hearts to realize that each of them, after having fought gallantly, one after another, the errors and the prejudices which lay ambushed along his way, was finally checked by some imaginary obstacle which he could not overcome, by a last prepossession which he durst not challenge. 2. THE HISTORY OF MEDICINE VERSUS THE HISTORY OF ART* IN REMEMBRANCE OF FIELDING H. GARRISON I I appreciate the honor of having been invited to deliver this lec- ture, and I welcome the opportunity of paying homage to the memory of an old friend, who was a distinguished historian and did perhaps more than anybody else to promote the cultivation of the history of medicine in our country. There is no medical or reference library, however small, without a copy of one of the edi- tions of his Introduction to the History of 'Medicine, and many American doctors have derived their knowledge of the subject al- most exclusively from it. They were fortunate in having such a good source of information, for Garrison's Introduction is, all considered, the best one-volume account of the medical past, espe- cially the more recent past which concerns more immediately our contemporaries. II The subject of my lecture was selected on two grounds. Firstly, it enabled me to reassess the views formulated in the essay intro- ducing 7s is t (1912); and secondly, it was a means of showing the humanity of Garrison's history. In spite of the lack of space (for the evocation of the whole medical past in less than a thou- sand pages is somewhat of an adventure) , Garrison always man- * The Fielding H. Garrison Lecture, read at the Seventeenth Annual Meeting of the Ameri- can Association of the History of Medicine, May 1941. + An international journal devoted to the history of science, the official quarterly organ of the History of Science Society. 15 16 THE LIFE OF SCIENCE aged to add the human touch without which history remains hope- lessly dull. He thus illustrated his own sensitiveness to the essen- tial if elusive values without which our life has no savor and hardly deserves to be recorded. He was especially sensitive to music: witness his many refer- ences to it. These references were of necessity very brief, but I shall expand two of them in order to bring forth their rich im- plications. I have the reputation of being a hard worker and among the physicians listening to me to-day are perhaps many who work as hard as I do, or harder still; yet, as compared with the famous Dutch physician, Hermann Boerhaave, we are but self-indulging weaklings. According to his early biographer, William Burton, The mornings and evenings he devoted to study, the intermediate part of the day to domestic and public affairs. He used to rise during summer at four in the morning, and at five in the winter, even in his later years; ten was his usual bed time. In severest win- ters he had neither fire nor stove in his study, where he passed the three or four first hours of the morning: his application to study was greater in the last ten years of his life, than in any space of equal duration from the year 1700. When business was over, he took the exercise of riding or walking, and when weary revived himself with music, his most delightful entertainment; being not only a good performer on several instruments, particularly the lute, which he accompanied also with his voice, but a good theorist likewise in the science, having read the ancient and best modern authors on the subject, as appears by the lectures he gave on sound and hearing; and during the winter he had once a week a concert at his own house, to which by turns were in- vited some select acquaintance of both sexes, and likewise pa- tients of distinction from other countries. His teaching should presumably be understood as a part of those "domestic and public affairs" which occupied the inter- mediate part of his day. Perhaps he thought, as many scholars do, that teaching was not real work but rather an interruption of it. MEDICINE VERSUS ART 17 And yet he taught a lot, not only clinical medicine and ophthal- mology (in 1708, he gave the first special course on that subject), but also physics, chemistry and botany! In those days, famous professors did not occupy a chair but a whole settee. Boerhaave's musical interest must have been deep, for he de- voted a special section to it in his autobiography. That section (XXII) is very brief (seven words) , but that is of a piece with the rest. Boerhaave was too busy a man down to his last day to in- dulge in reminiscences. Here it is : XXII. Fessus testudinis concentu solabatur lassitudinem. Mu- sices amantissimus. How eloquent are those few words ! Since I have read them and pondered upon them, Boerhaave is more alive to me than he was before, and I can almost see him with his "testudo" (not a tortoise that, but a lute) relaxing his mind when his duty was done. Ill The other story concerns Theodor Billroth (1829-94), one of the greatest surgeons of his time; the pioneer of visceral surgery. Whatever be his greatness or his shortcomings as a surgeon, we shall love him better if we realize that he was a life-long friend of Johannes Brahms (1833-97). Brahms and he became very inti- mate in Zurich, and when Billroth was called to Vienna, Brahms, being a bachelor and without position, followed him there. Though they spent much of their time together and often trav- elled together, they exchanged a great many letters, of which 331 are preserved. These letters deal chiefly with musical matters, most of Brahms' works being discussed in a friendly fashion. The sur- geon's villa in Alsergrund (a suburb of Vienna) became a mu- sical center. Indeed, he enjoyed the jus primae noctis over Brahms' new creations, and the friends of both masters were given oppor- tunities of hearing for the first time some of the masterpieces of chamber music. Did they appreciate their privilege? Probably 18 THE LIFE OF SCIENCE not. But we are interested here primarily in the relationship be- tween the composer and the doctor, — a relationship which is, I believe, unique in its intensity. Billroth was a good amateur, a clever pianist and a capable viola player much in demand for quartets (bless the gentle violists for we need them) . Under the combined influence of his scientific studies and of Brahms' conver- sations, Billroth devoted more and more thought to the psycho- physiological basis of music and gathered a number of notes on the subject which were edited after his death under the title "Wer ist musikaliscb?" by no less a person than Eduard Hanslick (1825-1904). Who remembers Hanslick to-day? Yet he was the leading critic of the German world, pontificating for a third of a century in the T^Jeue freie Vresse, defending with painful iteration the canons of "musical beauty" and of the "significant form" (beseelte Jorm). He was a member of the 'Brahmscjemeinde (Brahms clique) and was the champion of the Schumanns, of Brahms, of Dvorak against the 'Musik der Zukunft. If Liszt and Wagner irritated him so much what would he have thought, I wonder, of the musical anarchists of our own days, of the "jazz" and "swing," of all the music which seems to be written for the spinal cord rather than for the brain? At that time the arch-of- fender was Wagner, and I sometimes ask myself whether Hans- lick was not right in his distrust of the Wagnerian witchery? His- torians discussing our times a few centuries hence will be able to discern more clearly than we can the spiritual origins of the pres- ent chaos. They will probably recognize Wagner and Nietzsche as the leaders in the movement to pull Germany back to the Nibeluncjen level. IV There is considerably more to be said about medicine and music, but these two examples must suffice. It is more pleasant to talk about that, I think, than to write, for the talking would be less deliberate and we could digress more capriciously, and perhaps MEDICINE VERSUS ART 19 stop talking, to listen to music. For what is the good of talking about music? Let us listen. Take the Jhird piano cfuartet in C minor (op. 60) . When Brahms sent the finished work to Billroth in 1874 he wrote: ffI am showing you the quartet purely as a curi- osity! An illustration as it were, to the last chapter of the man in a blue swallow tail and yellow waistcoat. . . " Or take the two Rhapsodies for piano, dedicated to Frau Elisabeth von Herzogen- berg (op. 19, c. 1878). Listen, and remember Billroth's comment: "In these two pieces there lingers more of the titanic young Brahms than in the last works of his maturity." Without the music itself, either present or remembered, these words are mean- ingless, and there is no point in quoting more. Let us return to the history of medicine. I am afraid that many physicians think of it too much in terms of a list of discoveries and achievements. In fact, such lists have been compiled in such a dry and impersonal manner that the names of physicians asso- ciated with each "item" might almost be replaced by an x, y, or z. Such lists are useful, but they are to the history of medicine hardly more than a skeleton is to a living body. The skeleton is indispen- sable to be sure, but insufficient. A mere list of discoveries is a falsification of the history of medicine, even from the purely scientific point of view, for such a list exaggerates the discontinuities in medical progress. A deeper study of almost any discovery reveals that what we call the dis- covery is only the final clinching of an argument developed by many men throughout a long period of time. However, such a list is a far greater falsification from the broad human point of view. The history of science, and in particular the history of medi- cine (we can not repeat it too often) is not simply an account of discoveries. Its purpose is to explain the development of the scien- tific spirit, the history of man's reactions to truth, the history of the gradual revelation of truth, the history of the gradual libera- tion of our minds from darkness and prejudice. Discoveries are evanescent, for they are soon replaced by better ones. The his- 20 THE LIFE OF SCIENCE torian must try not only to describe these evanescent discoveries but to find in science that which is timeless. When he does that he comes very close to the historian of art. To put it in other words, a man's name may be immortalized by his discoveries. Perhaps there was nothing else in him deserving of remembrance? He may have been a poor sort of man, a man whose mind was as sharp and narrow as a knife-edge? Or else the historian betrayed him? In so far as a scientist is also an artist, his personality can survive, otherwise not. It is the historian's main duty to revive the personalities, rather than to enumerate their scientific excres- cences. Discoveries may be important, but personalities are in- finitely more so. V The materials investigated by historians of art often are of great value to historians of medicine, because artistic traditions are likely to be more tangible than purely scientific ones. This is espe- cially true of ancient and mediaeval times, during which the dif- fusion of knowledge was necessarily difficult and erratic. Beautiful monuments had on the whole a better chance of survival than others, and their language is easier to understand, even to-day. Dr. Sigerist has given remarkable examples of the mutual aid of the history of medicine and the history of art in his lecture, "The historical aspect of art and medicine/' Remember his pictorial his- tory of the plague, and his account of the transformation of Apollo into St. Sebastian, both being saviors or intercessors in times of pestilence. Such examples might easily be multiplied and a balanced ex- planation of them would enrich, as well as fortify, our traditions. I have adumbrated some of them in the first volume of 7sis — apropos of the history of cultivated plants — and in my Introduc- tion to the History of Science, e.g., indicating the importance of the pilgrimage roads, such as the Way of St. James (to Santiago MEDICINE VERSUS ART 1\ de Compostela) , and of the dispersion of Romanesque and Gothic architecture. Much as they are needed for the following up of Western tradi- tions, they are needed considerably more for the understanding of Eastern ones. Indeed, Western traditions are supported by literary witnesses in Greek, Latin or vernaculars which offer no special difficulties; while the Eastern literatures are generally closed to all but a few Orientalists, and the latter's knowledge is almost always restricted to a single group of languages. Now consider this case. In the beginning of the fourteenth century, a most remarkable cul- ture was developed in Tabriz under the patronage of the Mongol rulers of Persia. The spiritual leader was Rashid al-din, physician, theologian and one of the outstanding historians of the Middle Ages. He wrote chiefly in Persian, but had a deep knowledge of Arabic and was acquainted (directly or through secretaries) with documents written in Hebrew, Uighur, Mongolian and Chinese. A scientific edition of his works requires a good knowledge of all of those languages. This you will admit is a big order. Happily, the cosmopolitanism of that age and place can be perceived almost immediately by any person sensitive to artistic values and know- ing sufficiently the peculiarities of Asiatic arts. Indeed, under the patronage of the same Rashid al-din, there blossomed in Tabriz a school of miniaturists whose works reveal immediately the same Chinese influences which can only be detected in the text by that vara avis, an Orientalist as familiar with Chinese as with Persian and Arabic. Indeed Chinese traits are just as obvious in those fourteenth-century miniatures, as they were to become four cen- turies later in the ubiquitous "chinoiseries" which delighted our rococo ancestors. VI The view that we need art for the understanding of science and vice versa is by no means a new one, but it is so often forgotten or obscured by good scientists and by good historians that it is neces- 22 THE LIFE OF SCIENCE sary to give it from time to time new strength and new life, and to treat it as if it were a novelty, the most important novelty of our own time. Among the best exponents of it in the last century, was a man who was also one of the pioneers of our own studies. Can you guess whom I mean? I will help you. He should not be difficult to find, for he was, a hundred years ago, the most famous man in the world. He is not so famous now, for the wheel of for- tune never stops turning, even after one's death. He is a bit for- gotten, and when our schoolboys are asked to name the most prominent men, no one would think of choosing him. After having received a scientific preparation which was as elaborate as it was diversified, and having crowned it with a literary initiation in the Weimar circle (Goethe, so critical of others, never wavered in his admiration of him) , he spent five years exploring South America, then thirty more discussing and publishing the results of his ob- servations. At the age of fifty-eight he delivered in Berlin a series of lectures which were but the sketch of the grand fresco of which he began the publication eighteen years later and to which he de- voted the remainder of his life. That man is — need I name him — Alexander von Humboldt, and the work of his old age to which I referred is the Cosmos. The first two volumes appeared in 1845 and 1847 (when he was 76 and 78), vols. 3 and 4 between 1850 and 1858; he died in 1859 at the age of 90, and volume 5 appeared three years later. We need consider only the first two volumes. The first contains an elaborate description and explanation of the physical world, and the second is a history of science. Thus Humboldt was a pioneer in geographical synthesis, and also in historical synthesis. He was a founder of the new geography and also of the new history. The first innovation was rapidly understood and was developed in many countries; the second was comparatively neglected. Geog- raphy and history are two necessary bases of a man's education; just as some knowledge of geography removes his provincialism with regard to space — that is, teaches him that things are not necessarily better in his own village, in his own metropolis or in MEDICINE VERSUS ART 23 his own country than elsewhere — even so, a knowledge of history is the only way of removing his provincialism with regard to time — that is, of making him realize that things are not necessarily better in his days than in earlier or, maybe, in later ones. Neither geography nor history was new in Humboldt's days, but he in- creased considerably the scope and the implications of both. For example, he showed that history should be focussed upon the his- tory of science, and also upon the history of arts and letters; but most remarkable of all was his realization of the polarity of arts and sciences. After having described nature in volume one of the Cosmos, he devoted the second volume to a new description of nature as reflected in the human mind, by the imagination (that is art) or by the reasoning power (that is science) . In this respect, he was breaking ground so new that the vast majority of scientists and scholars of to-day have not yet grasped what he was trying to do. The project was so ambitious that realization fell far short of it, but we must not blame him. Pioneers are beginners; they cannot be expected to complete their task; it is not their business to com- plete it. Some day the substance of that second volume will have to be worked out again and rewritten, but it will take a man of unusual learning, artistry and wisdom to do it well. As I see it now, the great story which cries to be told is that of the rhythm of the mutual interrelations between science, art and religion. The story is very difficult to tell, because it is not a story of progress like the history of science, but of vacillations and vicissitudes, of harmony followed by chaos, and beauty mixed with horrors. It would be the story of man's sensitiveness to the fundamental problems and the main values of life. All honor to Alexander von Humboldt for having shown the way, and the more so that we are so slow in following it, and that our scientists, so intelligent in some respects, are so stupid in others, and our artists, so clever, yet so blind. Beauty is there for all to see, and truth, and virtue, but how few realize that they are but different aspects of the same mystery? 24 THE LIFE OF SCIENCE VII The mention of the mystery brings us close to the heart of our subject, for it is there on its threshold that art and knowledge and faith meet and kneel together. This will appear more clearly when we have examined how far art and science diverge in the ordinary routine of life. After having completed that examination, briefly as we must, we shall retrace our steps and peep once more into the sanctuary. The outstanding difference between art and science is that the latter is progressive while the former is not. Scientific activities are the only ones which are cumulative and progressive. Thus reading the history of science gives us the exhilarating feeling of climbing a mountain; we may go downward sometime for a short run, or we may turn around its slopes, but the general direction is upward, and the top of the mountain is lost in the clouds. Every scientist is enabled to start off from the highest level reached by his predecessors, and if he have it in him, to go higher still. The history of art, on the contrary, is like a glacial landscape, a plain wherein many hills are unevenly scattered. You may climb one of those hills and reach the summit, — but then you cannot continue without going down to the level land; then up again, and so on. When I began my ascension of the topless mountain, I used to gloat over that. Progress, here it was indeed and nowhere else. Unfortunately, there is the devil to pay for it. Because of the pro- gressive nature of science, its achievements are evanescent. Each one is bound to be superseded, sooner or later, by a better one and then it loses its practical value and becomes like a neglected tool in a museum showcase. On the other hand, because of art's very unprogressiveness, works of art are eternally young. It is very difficult to read an old scientific treatise, for in order to under- stand it properly, one must know equally well the old science and the new, and everything before and between. It is painful to read Newton, but the plays of Shakespeare are as timely and pleasur- able to-day as they ever were. <( A thing of beauty is a joy forever/' MEDICINE VERSUS ART 15 The following remarks made by Picasso in 1923 throw a curious light on this. Said he, To me there is no past or future in art. If a work of art can- not live always in the present it must not be considered at all. The art of the Greeks, of the Egyptians, of the great painters who lived in other times, is not an art of the past; perhaps it is more alive today than it ever was. Art does not evolve by itself, the ideas of people change and with them their mode of ex- pression. When I hear people speak of the evolution of an artist, it seems to me that they are considering him standing between two mirrors that face each other and reproduce his image an in- finite number of times, and that they contemplate the successive images of one mirror as his past, and the images of the other mirror as his future, while his real image is taken as his present. They do not consider that they all are the same images in different planes.* Science is progressive and therefore ephemeral; art is non- progressive and eternal. A deeper contrast could not be imagined. In the field of science, the methods are supremely important. A history of science is to a large extent a history of the instruments, material or immaterial, created by a succession of men to solve their several problems. Each instrument or each method is, as it were, a crystallization of human genius. Look at the cockpit of an airplane, and ask yourself what was the origin and development of each one of its tools; it is an endless story of patient accumula- tion and adjustment. In art, on the contrary, the results matter more than the methods. I am not interested in knowing how a symphony was produced, how a fresco was painted, how a dish was cooked. The beauty of the symphony and the painting satisfy me, and so does the tastiness of the food; I do not ask for the recipe. The scientist strives to be more and more objective and accu- rate; the artist lets himself go and his accuracy is intangible. The * Picasso, forty years of bis art, 2nd ed., edited by Alfred H. Barr, Jr., issued by Museum of Modern Art (New York, 1939, p. 11). 76 THE LIFE OF SCIENCE scientist says : "If you can measure the thing, you are beginning to know something about it, if not . . . " but the artist answers, "What about beauty and love?" Science is essentially international, or perhaps we should say supernational. Men of science of all times and places cooperate together; they cannot help cooperating, even if they don't particu- larly wish to do so, because their task is essentially the same. They are ascending the same mountain, and even when their trails di- verge they are aiming at the same goal. Art is tribal, national. To be sure, it may transcend local peculiarities and reach the bed- rock of human nature. Yet when we speak of Spanish painting or Russian music we evoke fundamental differences, which may be difficult to analyze, not to say measure, but are as tangible as the air we breathe. Sometime ago I had to write a study on Borodin, who was a distinguished chemist as well as one of the leading Russian composers. In order to reconstruct his background, I had to investigate the contemporary state of international chemistry and of Russian music. The scientific procedure is essentially analytic; the artistic one synthetic, intuitive. Scientific discoveries are the result of long evolutions, artistic achievements of short involutions. This applies not only to the creation of scientific or artistic works, but also to their interpretation. We cannot penetrate the thought of Faraday or Poincare without a sustained effort, but a Greek statue reveals to us immediately the best of Greece, and a Gothic cathedral il- luminates the Middle Ages. Science is the field of arduous and unremitting work; how beautiful the flowers in it are if we have earned them with honest travail of limbs or spirit! Art, by con- trast, is the paradise of immediate intuitions. VIII All of which is very true, but it is not the whole truth, and I knew it all the time. Now let us look together at the other side of the picture. MEDICINE VERSUS ART 27 In science as in art, there is always a fundamental need of selec- tion. Just as an artist cannot paint every landscape, or a lover love every woman, just so the scientist cannot investigate every prob- lem. None of them has a ghost of a chance unless he restricts his goal. The immense success of science is due largely to the selec- tion of problems, one at a time, the simplest and easiest first, and so on. Genius in science as well as in art is essentially the ability to select properly. Then, too, there is technical progress in art. The history of music, like the history of science, can be written partly in terms of instruments. The modern symphony is as much an instrumental triumph as the transatlantic flights. Scientific knowledge is not simply rational, a good part of it is manual and intuitive. What a gulf there is between the born diagnostician and the physician who has learning enough but lacks insight! There is uncanny wis- dom in the hands of a surgeon as well as in those of a pianist. Science and art have both their collectivist aspects, as well as their individualist ones. The former are seen at their best in re- ligious art and in social medicine, and that rapprochement is sug- gestive. For what is religious art, but the highest form of the social art? And what else is social medicine but the finest realization of the second commandment: 'Thou shalt love thy neighbor as thyself"? Neither religious art nor social medicine can succeed unless they be sustained by a living faith. Science, every science and of course medicine above all, is an art as soon as it is applied. It becomes part and parcel of a man's religion as soon as he is thoroughly conscious of his own in- significance and of his solidarity with the rest of the universe. We cannot understand the history of medicine, unless we see in it not only discoveries and scientific achievements, but also personal de- feats and victories, the timeless fruits of men's love and faith. On the other hand, as Canon Streeter has remarked: "Science is the great cleanser of the human spirit, it makes impossible any religion but the highest." The well-tempered historian will keep this in mind always, and think of men's art and religion, as well as of 28 THE LIFE OF SCIENCE their learning. He will try to see the whole of their personalities and thus give to his own work its greatest value for other men. Science is the reason, art the joy, religion the harmony, of life. None is complete without the others. We cannot hope to under- stand the mystery of life unless we be prepared to consider it from these three angles, and this means, first of all, that we must drop our scientific conceit, and second, that we must never, never, sub- ordinate humanities to technicalities. 3. THE HISTORY OF SCIENCE The history of science is the study of the development of science, — just as one studies the development of a plant or an animal — from its very birth. We try to see it grow and unfold itself under many diverse conditions. And it is not enough — as we shall see further on — to study separately the development of each science; one has to study the development of all the sciences simultane- ously. Besides, it is impossible to separate them satisfactorily one from the other; they grow together and mingle continually in innumerable ways. While numberless books, many of them excellent, are published every year on the history of literature, of art, of religions, how is it that there is not yet a single history of science that can be com- pared with the best of them? When so many institutions, libraries, lectureships have been dedicated to the history of everything, how is it that the history of science has been so much neglected? People who have no knowledge of science, or but slight, are afraid of it. They are not inclined to read a book dealing with the history of science, because they think they are not equal to appreciating it. Now this is a mistake: every intelligent man or woman can understand the development of science, at least if it be properly presented and taken from the beginning. More than that, I am convinced that the historical method is the best for con- veying scientific facts and ideas to unprepared minds and to make them thoroughly understandable — at least that is so in the case of grown-up people. On the other hand, those who know science — or are supposed to know it because they have made a special study in some narrow field — are often given to viewing history with contempt. They think that the study of history is hopelessly inaccurate and, according to their own definition of science, un- scientific. This is another mistake, which, however, it would take too long to refute completely. Suffice it to say that historical stud- 29 30 THE LIFE OF SCIENCE ies, like all other studies, are approximate; the approximation ob- tained by historians may be looser, but the studies are none the less scientific for that. It is not so much its degree of approxima- tion, as a definite knowledge of this degree, that gives to a study its scientific character. Scientists and philosophers are at the present time unanimous in wishing that the general tendencies and fundamental principles of science be constantly extricated, criticized and stated with more precision. They are well aware that this is now an essential condition of progress and security. But how will it be possible to conciliate the imperious needs of synthesis and the division of labor? It would seem that the only possible solution is that which was recommended by Auguste Comte and partly realized by him- self and his disciples : namely, to originate a new great specialty, the study of scientific generalities. To secure the unity of knowl- edge, it will be more and more necessary that some men make a deep study of the principles and of the historical and logical de- velopment of all the sciences. Of course, they will not be expected to be perfectly acquainted with all the technical details, but they must have at their command a thorough knowledge of the great lines and of the cardinal facts of each science. It is a very difficult but not an impossible task. The inconveniences of excessive spe- cialization will be happily counterpoised by this new branch of knowledge, which induces a collaboration of philosopher, his- torian and scientist. It will appear clearly from the following pages that the best instrument of synthesis, and the most natural hyphen between scientist and philosopher is the history of science. Auguste Comte must be considered as the founder of the his- tory of science, or at least as the first who had a clear and pre- cise, if not a complete, apprehension of it. In his Cours de philo- sophic positive, published from 1830 to 1842, he very clearly brought forward the three fundamental ideas which follow: (1) A synthetic work like his cannot be accomplished without having HISTORY OF SCIENCE 31 constant recourse to the history of science; (2) It is necessary to study the evolution of the different sciences to understand the de- velopment of the human mind and the history of mankind; (3) It is insufficient to study the history of one or of many particular sciences; one must study the history of all sciences, taken to- gether. Besides this, as early as 1832, Auguste Comte made an application to the minister Guizot for the creation of a chair, de- voted to the general history of the sciences (histoire generate des sciences). It was sixty years before this wish of his was granted; and the course entrusted to Pierre Laffitte was inaugurated at the College de France in 1892, thirty-five years after Comte's death. Another French philosopher, Antoine Cournot, also helped to clear up our ideas by the publication in 1861 of his book Iraite de Vencbainement des idees fondamentales dans \es sciences et dans I histoire. However, the real heir to Comte's thought, from our special point of view, is neither Laffitte nor Cournot, but Paul Tannery. It is hardly necessary to say much of him, because all who have the slightest knowledge of the history of science must needs have come across one of his numerous memoirs, all so re- markable for their originality and exactitude. Paul Tannery him- self attached importance to his intellectual connection with Comte and often expressed his admiration for the founder of positivism. Tannery's philosophy is very different from Comte's, but the greatest difference between them is that Comte's knowledge of the history of science was very superficial, whereas Paul Tannery, being extremely learned and having at his disposal a mass of his- torical research work which did not exist in the thirties, knew more of the history of science than anybody else in the world. Certainly no man ever was better prepared to write a complete history of science, at least of European science, than Paul Tan- nery. It was his dream to carry out this great work, but unfortu- nately he died, before realizing his ambition, in 1904. One can understand the history of science in different ways, but these different conceptions do not contradict each other; they are simply more or less comprehensive. My own conception does 32 THE LIFE OF SCIENCE not differ much from Tannery's, except that I attach more im- portance to the psycho-sociological point of view. Auguste Comte had noticed all the bonds that unite the differ- ent sciences, but he did not give enough attention to them. If he had understood that these interactions and this interdependence have existed in all directions from the very beginnings of science, would not the rigid framework of his Cours de philosophie have burst asunder? On the other hand, some people seem to think that it is impos- sible to write the history of science as a whole, that the subject is too great. I should rather say that the impossibility is to pick out from this inextricable network the development of one single branch of human knowledge. Moreover, it is actually impossible to write the history of any important discovery without writing, willingly or not, a chapter of the history of science — I mean the history of science as a whole. How could we explain, for instance, the discovery of the circulation of the blood if we did not explain the evolution of anatomy, of comparative zoology, of general biology, of natural philosophy, of chemistry, of mechanics? Like- wise, to make clear how the determination of longitudes at sea was discovered, little by little, we have to resort to the history of pure and applied mathematics, the history of astronomy and navi- gation, the history of watch-making, etc. It would be easy enough to give more examples of the same kind. Further, it is only by considering the history of science as a whole that one can appraise the scientific level of a definite period or of a definite country. It has happened more than once that one science became neglected while others were thriving, or that scientific culture moved from one country to another. But the his- torian is not deluded by these facts, and he does not think that human genius is suddenly quenched or rekindled; from his syn- thetical standpoint he sees the torch of light pass from one science to the other or from one people to another. He perceives better than anybody else the continuity of science in space and time, and he is better able to estimate the progress of mankind. HISTORY OF SCIENCE 33 But the historian's mind is not satisfied with the study of the interactions between the different sciences. He wishes to study- also the interactions between the different sciences, on one hand, and all the other intellectual or economic phenomena, on the other. As a matter of fact, he has to give a great deal of attention to these reciprocal influences, but of course he does not forget that the aim of his work is essentially to establish the connecting links between scientific ideas. In short, the purpose of the history of science, as 7 understand it, is to establish the genesis and the development of scientific facts and ideas, taking into account all intellectual exchanges and all influences brought into play by the very progress of civiliza- tion. It is indeed a history of human civilization, considered from its highest point of view. Ihe center of interest is the evolution of science, but general history remains always in the background. It follows from this definition that the only rational way to sub- divide this history is not at all to cut it up according to countries or to sciences, but only according to time. For each period of time, we have to consider at once the whole of its scientific and intellec- tual development. Of course, to make this general synthesis possible, it will often be expedient, even necessary, to write monographs or partial syntheses of different kinds. For instance, the study of the archives of a definite place leads naturally to the drawing up of an essay on the history of science in that place. On the other hand, a spe- cialized scientist will be tempted to look up the genealogy of an idea in which he is particularly interested, or to write the biog- raphy of a forerunner whose work and genius he can better ap- preciate than anyone else. But all this research is necessarily incomplete and does not acquire its proper significance so long as it cannot be inserted properly into a history of the sciences of the same age. It may be worth while to add that all monographs are not equally useful; some are so clumsy and absurd that they obscure, mislead and delay the next synthesis. To elaborate our historical work we have, of course, to use the 34 THE LIFE OF SCIENCE same methods that are used by ordinary historians to appraise and criticize the materials available to them. But the historian of science has to use, independently, some other methods of a more special nature. I cannot explain them here, but it is easy to under- stand that, for instance, to establish at what date a discovery be- came a real part of science and enriched human experience, the historical exegesis must be supplemented by a scientific exegesis, based on the evidence given by the positive sciences. We must try to marshall all scientific facts and ideas in a defi- nite order; this means that we must try to assign to each of them a date as precise as possible — not the date of their birth or of their publication, but that of their actual incorporation into our knowl- edge. Likewise, biographers have to exert themselves to find pre- cisely during which periods the influence of great scientists was the most felt, in order to range them in chronological series. This is generally a very difficult thing to do, and the reader will not fail to appreciate the work that is discreetly accomplished by such scholars. Such work of erudition is the bed-rock on which all his- torical writing is built up. These remarks complete and add precision to our definition of the history of science. However, it may be well to give some more details about the different exchanges which the historian has to consider in order to put the evolution of science in its proper light. I shall successively examine some of the other departments of life which are the most interesting for the historian of science: (1) General history or the history of civilization; (T) The history of technology; (3) The history of religions; and (4) The his- tory of fine arts, and arts and crafts. 1. Science and Civilization. Since the eighteenth century, and notably under the influence of Vico, Montesquieu and Voltaire, the conception of history has become more and more synthetic. History, the principal interest of which once consisted in military records and court annals, is growing up into a history of civiliza- tion. It stands to reason that a sufficient knowledge of the history HISTORY OF SCIENCE 35 of civilization is absolutely necessary for the historian of science, were it only to locate the scientific facts in the very surroundings that gave rise to them. On the other hand, the historian of civilization can no longer remain unacquainted with the history of science. Some of the most recent historical manuals contain paragraphs devoted to it. It is true, the space allowed is rather scanty, but that is a begin- ning. I feel confident that, before long, general histories will be written in which the history of science, far from being banished to some obscure corner, will be the very center of the picture. Is not science the most powerful factor of evolution? Some examples will illustrate the significance of the history of civilization. How can one account for the fact that the Latin manuscripts containing translations of Greek authors made from Arabic texts for so long barred the way to the printed translations that had been elaborated directly from the Greek texts? The latter, indeed, were much better. Bjornbo has given some reasons that are very probably the true ones. The printed books that nobody cared to copy became rarer and rarer. On the other hand, the manuscripts were copied over and over again and continually multiplied. Besides, the copyists lacked knowledge and critical sense to a great extent, and they could not help being favorably impressed by the bulk of Arabic literature. Mere scientific reasons do not suffice to explain the creation of the metric system by the French revolutionaries. This creation was also in part a reaction against the "foot of the king" of the ancien regime. Financial or tariff regulations or the promulgation of labor laws can transform the business life of a country and, indirectly, its scientific production. To understand the beginnings and development of geography one has to take into account many facts that are quite foreign to science. For instance: the quest for mythical treasures; con- querors' ambitions; religious proselytism; the adventurous in- stincts of daring young men. 36 THE LIFE OF SCIENCE Lastly, it is necessary to know the history of epidemics and to study all the social facts that have been their causes or their re- sults, to estimate correctly the evolution of medical ideas. 2. Science and technology. Industrial requirements are always putting new questions to science, and in this way they guide, so to say, its evolution. On the other hand, the progress of science con- tinually gives birth to new industries or brings new life to old ones. It follows that the history of science is constantly inter- woven with the history of technology, and that it is impossible to separate one from the other. Let us see some examples. After exhaustion-pumps had been in- vented, there was such a demand for good pumps of this kind that special workshops were founded in the beginning of the eighteenth century, in Leyden, Holland, to make them, and of course these workshops soon undertook to make other scientific instruments. It is hardly necessary to point out how intimately connected the making of these instruments is with the history of physics or as- tronomy. A geological discovery suffices to revolutionize a whole country and transform an agricultural nation into an industrial one. Of course, a transformation as complete as this involves a radical change in scientific needs. The working of mines has always exerted such a deep influence on the evolution of science and civilization that one might compare the importance of mines in the history of science with that of temples in the history of art. L. de Launay has very clearly shown that the silver mines in Laurion played a considerable part in the history of Greece. The history of chemistry would sometimes be unintelligible if the history of chemical industries was not studied at the same time. Let me simply remind the reader of the case of coloring matters. Industrial research made in this direction has deeply in- fluenced the progress of organic chemistry. On the other hand, it is well known how much has been done to improve this industry by the scientists of the German Chemical Society. HISTORY OF SCIENCE 37 A chemical discovery can revolutionize a whole country, just as completely as a geological one; as soon as it becomes possible to realize, on a business basis, the chemical synthesis of a natural product (like indigo, vanilla, India rubber), the agricultural in- dustry and civilization of immense countries are in danger. Technical inventions are more precisely determined every day by industrial needs. The manufacturer can often say very defi- nitely to the inventor: "This is the invention which I now need to improve my production." Besides, every invention starts a series of others that the first has made necessary and that it would have been impossible to realize, or even to conceive, previously. Lastly, commercial needs also influence the development of the sciences, not only the natural sciences and geography (that is too obvious to dwell upon), but even mathematics. It is necessary to take into account the evolution of book-keeping and banking business to understand thoroughly the introduction and the spread of Hindu- Arabic numerals into Europe, and later the invention of decimal fractions. It is also owing in great measure to commercial requirements that many astronomical discoveries were made, and that the different systems of weights and measures were created. 3. Science and Religion. Science and religion have never ceased to influence one another, even in our own time and in the coun- tries where science has reached a high degree of perfection and in- dependence. But of course the younger science was, and the farther we go back through the ages, the more numerous these inter- actions are. Primitive people cannot separate scientific or technical ideas from religious ones, or, more exactly, this classification has no sense to them. Later, when the division of labor had created some scientists or engineers, distinct from the priests, or at least had given birth to a class of priests who had undergone a higher scientific training than their colleagues, even then the interpreta- tion of the holy books, the observance of rites, the needs of agri- culture and medicine, the making of the calendar, and above all, the hopes, the fears and the anxieties of a very precarious exist- 38 THE LIFE OF SCIENCE ence, have been innumerable links between science and religion. The great plagues, and generally all cataclysms, for instance earth- quakes or wars, have been followed by religious revivals and often by violent outbursts of religious fanaticism. On the other hand I know many cases where the priests them- selves have been the transmitters of knowledge from one genera- tion to the following. The best example of this can be found during the period extending from the end of the second school of Alexandria to the ninth century. We owe, if not the advance- ment of science, at least its conservation, to the doctors of the Latin and Greek churches, to the Nestorians and other heretics. In some other cases the influence of religion is less direct, but not less important. For instance, A. de Candolle has proved that the Protestant families which were exiled from the Catholic coun- tries of Europe during the sixteenth and seventeenth centuries and even during the eighteenth, have given birth to an extraor- dinarily high number of distinguished scientists. This is not to be wondered at. These people who preferred the misery of exile to moral servitude were certainly above the average in their conscien- tiousness and earnestness. The interactions between science and religion have often had an aggressive character. There has been, most of the time, a real warfare. But, as a matter of fact, it is not a warfare between science and religion — there can be no warfare between them — but be- tween science and theology. It is true that the man in the street does not easily differentiate between religious feelings and faith, on one side, and dogmas, rites and religious formalism, on the other. It is true also that the theologians, while affecting that re- ligion itself was aimed at when they alone were criticized, have not ceased from aggravating these misunderstandings. An excel- lent proof of this has been given in this country. One of the great men of these United States, Andrew Dickson White, pub- lished a splendid book on 7he Warfare Between Science and Jheohgy. Mr. White was a very godly man, and his book is, it is hardly necessary to state, extremely liberal and indulgent to every- HISTORY OF SCIENCE 39 body. Notwithstanding this, the author and his book had to bear the attacks of a great many fanatics. One of the saddest results of these misunderstandings is that some very religious and sincere souls have been misled and have treated science as an enemy. Another important result is that the evolution of science is very intimately interwoven with that of re- ligions and their heresies. 4. Science and Art. It may be useful to tender some remarks upon the different characteristics of scientific and artistic work before pointing out what is interesting from our point of view in the history of art. In the history of art as it is generally taught, very little is said about technicalities. Are there many people who know, or care to know, what kind of colors Botticelli used, or what were the tools of Phidias? We love a work of art for itself. It is essentially the ultimate result that interests us, not the meth- ods used to obtain it. In the domain of learning, on the contrary, the result is generally less interesting than the methods em- ployed to reach it. The history of science is not merely a history of the conquests of the human mind, but it is much more a study of the instru- ments— material and intellectual instruments — created by our in- telligence; it is also a history of human experience. This long experience of the past has much more significance for the scien- tist than for the artist. The artist admires the work of his fore- runners, but the scientist does more than admire, he makes actual use of it. The artist may find an inspiration in it, but the scientist tries to incorporate it entirely in his own work. It is very difficult to conceive progress in art. Does Rodin carve better than Ver- rocchio or Polycletus? The pictures by Carriere, by Watts, or by Segantini : are they finer than those by Fra Angelico, by Van Eyck or by Moro? Have these questions even any sense? In the domain of science the matter is quite different. Un- doubtedly it would be foolish to discuss whether Archimedes was more or less intelligent than Newton or Gauss; but we can in all 40 THE LIFE OF SCIENCE security assert that Gauss knew more than Newton, and that Newton knew more than Archimedes. The making of knowledge, unlike that of beauty, is essentially a cumulative process. By the way, this is the reason why the history of science should be the leading thread in the history of civilization. Nothing that has been done or invented gets lost. Every contribution, great or small, is appreciated and classified. This cumulative process is so obvious that even very young men may be better informed and more learned than their most illustrious forerunners. As a matter of fact, they are standing on the shoulders of their predecessors, and so they have a chance to see further. If they are not very intel- ligent they may be inclined to think that it is useless to study his- tory, under the misapprehension that they already know from the past all that is really worth knowing. In short, we are not sure that men become more intelligent — that is, whether intelligence increases — but we know positively that human experience and knowledge grow every day. As I have said, one does not pay much heed to mediocre artists. What they do has not much importance. On the contrary, in the laboratories, libraries and museums where science is slowly growing — like an ever-living tree — enormous quantities of excellent work is done by thousands of men who are not unusually intelligent, but who have been well trained, have good methods and plenty of patience. Scientific work is the result of an international collaboration, the organization of which is perfected every day. Thousands of scientists devote their whole lives to this collective work — like bees in a hive — but their hive is the world. This collaboration does not take place simply in space, but also in time; the oldest astro- nomical observations are still of some use. Perhaps this collective nature of scientific work is one of the causes of the general indif- ference concerning its history — indifference strongly contrasting with the widespread curiosity about the history of literature and the fine arts. Science aims at objectivity; the scientist exerts him- self to decrease to a minimum his "personal equation." Works of art, on the contrary, are extremely individual and passionate; so HISTORY OF SCIENCE 41 it is not to be wondered at that they excite more sympathy and interest. The history of the fine arts and of literature is generally con- sidered as a history of the great artists and of the works they have bequeathed to us. But one could adopt a different point of view: just as the history of science gives us the materials of an evolu- tion of human intellect, so one could look to the history of arts and of literature for the story of the evolution of human sensibil- ity. The history of science is a history of ideas; just so the history of art could be considered as a history of man's dreams. Under- stood in this way, the two histories complete and enlighten one another. The interactions between science and art have been particu- larly vivid at times in naturalistic reactions against scholastic and pedantic excesses. It would be extremely interesting to make a closer study of the rhythm of the different tendencies that swayed plastic arts and music, and to look for similar rhythms in the con- temporary succession of scientific theories, or more exactly, atti- tudes. The appearance of men of genius, who were at one and the same time artists and scientists — such as Leonardo da Vinci, Albrecht Diirer and Bernard Palissy — gives us a splendid oppor- tunity to study these interactions in their deepest and most fasci- nating form. On the other hand, it is a fact that scientific ideas have often been transmitted by works of art; moreover, for all the period preceding the beginnings of popular printing, these works of art give us direct testimonies — often the only ones we have — of inestimable value. For instance, it would be impossible to trace the history of ancient chemistry but for all the works of art and decoration that have come to us; and, to understand the history of chemistry, not only in ancient times but even up to the thresh- old of the seventeenth century, it is still necessary to study the development of the arts and crafts — the art of the potter, glass- maker, chaser, jeweler, miniature-painter, and enameler. But the history of art helps us, above all, to understand the spirit and the soul of vanished civilizations. From this point of 42 THE LIFE OF SCIENCE view, works of art have an immense superiority over every other manifestation of the human mind; they give us a complete and synthetical view of times gone by; they offer us the information that we need at a glance; they bring the past to life again. A granite sphinx, a Nike, a picture by Giotto or by Breughel, a Gothic cathedral, a mass by Palestrina — all these things teach us more in one flash than living men could do by long discourses. The following examples will show what kind of information the history of art can give us. It is by comparing various monuments that Viollet le Due has been able to find out some of the principal commercial roads of the twelfth century. Illustrations from Roman monuments give us exact information as to the origin of domestic and medical plants. Indeed, it is through Greece and Rome that most of them were introduced from the East into Europe. The his- tory of these plants tells us all the vicissitudes that modified the commercial and intellectual relations between those peoples. Here is another very curious fact. The great botanist H. de Vries dis- covered the variety monophylla of 7ragaria vesca in a picture by Holbein the Elder ("The Saint Sebastian of Munich/' dated 1516). This variety is now cultivated in botanic gardens as a rarity. One guesses that similar discoveries, however small they may appear, sometimes accomplish the solution of historical prob- lems. Lastly, I wish to note that the history of science is also, to a certain extent — perhaps less than some mathematicians think, but much more than the artists suppose — a history of taste. Leaving aside the external beauty of many books of science, for many scientists were splendid writers (think of Galileo, Descartes, Pas- cal, Goethe, Darwin) , the very substance of their work has often a great aesthetic value. Scientists who are men of taste very easily distinguish the scientific theories that are beautiful and elegant from the others. It would be wrong to ignore this distinction, be- cause this beauty and harmony, that the average person cannot see but that the scientist does see, is extremely deep and significant. One might ask : 'These theories that are more beautiful — are they HISTORY OF SCIENCE 43 more true?" Anyhow, they are easier to grasp and more fertile; and for these reasons alone it is worth while to give them our preference. THE SCIENTIFIC POINT OF VIEW The history of science has a great heuristic value, especially if it has been worked out by somebody who is as well acquainted with modern scientific tendencies as with ancient ones. The se- quence of old discoveries suggests similar concatenations to the scientist, and so enables him to make new discoveries. Disused methods, cleverly modified, may be rendered efficient again. When this is understood, the history of science becomes really a research method. A great scientist of our own time, Ostwald, has even gone so far as to say that, "It is nothing but a research method." We do not admit that much. Anyhow, new and old science com- plete and continuously help one another to advance and to di- minish the unknown that surrounds us everywhere. Does this idea not illuminate our conception of universal scientific col- laboration? Death itself does not interrupt the scientist's work. Theories once unfolded are eternally living and acting. To give to our history all its heuristic value, it is not sufficient to retrace the progress of the human mind. It is also necessary to remember the regressions, the sudden halts, the mishaps of all kinds that have interrupted its course. The history of errors is extremely useful; for one thing, because it helps us to better ap- preciate the evolution of truth; also because it enables us to avoid the same mistakes in the future; lastly, because the errors of science are of a relative nature. The truths of today will perhaps be considered tomorrow, if not as complete mistakes, at least as very incomplete truths; and who knows whether the errors of yesterday will not be the approximate truths of tomorrow? Simi- lar rehabilitations frequently occur, and the results of historical research often oblige us to admire and honor people who have been misunderstood and despised in their own time. This inci- 44 THE LIFE OF SCIENCE dentally proves that the study of the history of science has also some moral advantages. However, the history of superstitions and errors must not make us forget that it is the history of truth — the most complete and the highest truths — that interests us primarily. Besides, one may aim at retracing the history of truth in its entirety, because it is naturally limited; but the history of errors is infinite! Therefore it is necessary to fix some artificial limits to the latter and to choose judiciously between the errors and the superstitions. A great simplification is obtained by classifying the errors in groups. Indeed, the same mistakes and superstitions appear over and over again in different shapes, and it is useful to know the various types of errors in order to understand the mechanism of intellect. It is much to be regretted that many scientists decline to admit the utility of historical research, or consider it simply as a kind of pastime of small importance. They base their contempt on the following argument: "All the best of ancient science has been assimilated and incorporated in our own science. The rest only deserves oblivion, and it is awkward to over-burden our memory with it. The science that we are learning and teaching is the result of a continuous selection which has eliminated all the parasitic parts in order to retain only that which is of real value/' It is easy to see that this argument is not sound. For one thing, who will guarantee that the successive selections have been well made? This is so much the more a matter of doubt in that this se- lective and synthetic work is generally done not by men of genius, but by professors, by authors of textbooks, vulgarizers of all kinds, whose judgment is not necessarily irreproachable and whose intuitions are not always successful. Besides, as science is constantly evolving, and as new points of view are introduced every day, any idea that has been neglected may be considered later on as very important and fertile. It often happens also that some facts, scarcely known, all at once become very interesting, because they can be inserted into a new theory that they help to illustrate. Of course scientific syntheses — such as those represented by our HISTORY OF SCIENCE 45 textbooks — are indispensable. Without them science could hardly be transmitted from one generation of students to the next, but it must be understood that they are always provisional and pre- carious. They must be periodically revised. Now, how would that be possible if the history of science did not show us our way through all the unutilized experience of the past? History is, so to say, the guide, the catalogue without which new syntheses and selections made from fresh points of view would hardly be pos- sible. All the vicissitudes and recantations of science prove con- clusively that no man can ever flatter himself that he has definitely and completely exhausted a scientific fact or theory. No particle of human experience, however small, can be entirely neglected. To assert this is to assert, at the same time, the necessity of his- torical research. Moreover, among scientific works there are some, the genesis of which cannot be explained in the ordinary analytical way. They introduce abrupt discontinuities into the evolution of science, because they so far anticipate their own time. These works of genius are never entirely explored, and the interest they offer is never entirely exhausted. It is perhaps because it is almost inexhaustible, that true genius is so mysterious. Sometimes cen- turies pass before the doctrines of a man of genius are appraised at their true value. A great deal of benefit is still to be reaped from reading in the works of Aristotle, Diophantus, Huygens or New- ton. They are full of hidden treasures. It is a gross mistake to think that there is nothing more in such works than the facts and ideas which are positively formulated; if that were true, of course, it would be useless to refer to them: the enunciation of these facts and ideas would suffice. But that is not true, and I cannot but ad- vise those who have any doubt about it, to try. They will find that nothing excites the mind more than this return to the sources. Here, also, it is the historian's business to point out to the scien- tist the very sources where he will most likely invigorate his mind and start a fresh impulse. I wish now to give a few examples to illustrate the preceding 46 THE LIFE OF SCIENCE remarks. Any amount of them can be found in the history of medicine; we need but recall how greatly the whole of medical evolution has been influenced by the Hippocratic teaching, our modern ideas on humorism and naturism; or, again, the organo- therapeutic theories. Not only are the old ideas restored to vogue, but it sometimes seems that a kind of rhythm brings them back to light periodically. Georges Bohn has shown the periodical return, in the domain of comparative psychology, on one hand, of the animistic and anthropomorphic conceptions, and on the other hand, of the positivist conceptions. As a rule, the further science is removed from the mathematical form, the more likely these vicissitudes are. One can also say that when science is more accurate, that is to say, when the domain of uncertainty and hypothesis becomes narrower, the oscillations of the mind between divergent points of view are so much the less numerous, — but they do not cease entirely. Thus E. Belot reintroduced into cosmology, in a very seductive shape, the vortex theory that one would have thought had been entirely banished by Newton's criticisms. Similarly weighty reasons exist for reinstating into optics the emission theory, which seemed to have been forever exploded by the discoveries of Huygens, Young and Fresnel. But the best examples of such return to ancient knowledge are given to us by the history of technology. The history of chemical industries is very significant from this point of view : this is due to the fact that here economic conditions play a considerable part. In order that an invention may be realized it does not suffice that it be theoretically possible; it must pay. Now thousands of circum- stances continually modify the material factors which the engineer is struggling with; many are of such a nature that nobody could foresee them, or (what amounts to the same thing) , that it would cost too much to insure oneself against all of them. If new products appear on the market, or if the prices of some of the raw materials happen to vary considerably, or if new discoveries are made, or if new residues are to be employed, old methods that were once too expensive may become economical, or vice versa. Hence the HISTORY OF SCIENCE 47 chemist and the engineer have a vital interest in knowing the processes that have fallen into disuse, but to which the very progress of science may give from one day to the next a new career. The history of science is to them, so to say, what aban- doned mines are to the prospector. But in my opinion, however important its heuristic value may be, there are still deeper reasons why the scientist should give his attention to the history of science. I am thinking of those which have been so splendidly illustrated by Ernst Mach in his "Mechanics. For one thing, it is obvious that "they that know the entire course of the development of science will, as a matter of course, judge more freely and more correctly of the significance of any present scientific movement than they who, limited in their views to the age in which their own lives have been spent, con- template merely the momentary trend that the course of intellec- tual events takes at the present moment." In other words, in order to understand and appraise at its just value what one possesses, it is well to know what the people possessed who came before us; this is as true in the domain of science as it is in daily life. It is historical knowledge that discloses to the scientist his precise at- titude toward the problems with which he has to grapple, and that enables him to dominate them. Moreover, while research workers exert themselves to extend the boundaries of science, other scientists are more anxious to ascertain whether the scaffolding is really solid, and whether their more and more daring and complex edifices do not risk giving way. Now the task of the latter, which is neither less important nor less lofty than that of discovery, necessarily implies a return to the past. This critical work is essentially of an historical nature. While it helps to make the whole fabric of science more coherent and more rigorous, at the same time it brings to light all the acci- dental and conventional parts of it, and so it opens new horizons to the discoverer's mind. If that work were not done, science would soon degenerate into a system of prejudices; its principles 48 THE LIFE OF SCIENCE would become metaphysical axioms, dogmas, a new kind of revelation. That is what some scientists come to, who, for fear of falling into literature or "metaphysics" (as they put it) , banish all histor- ical or philosophic considerations. Alas! the exclusive worship of positive facts makes them sink into the worst kind of metaphysics — scientific idolatry. Fortunately, it happens at certain periods of evolution that re- sounding and paradoxical discoveries make an inventory and a thorough survey of our knowledge more obviously necessary to everybody. We are fortunate enough to be living at one of these critical and most interesting periods. The purpose of historical criticism is not merely to render science more accurate, but also to bring order and clarity into it, to simplify it. Indeed, it is the survey of the past that enables us best to extricate what is really essential. The importance of a concept appears in a much better light when one has taken the trouble to consider all the difficulties that were surmounted to reach it, all the errors with which it was entangled, in short, all the previous life that has given birth to it. One could say that the riches and fertility of a concept are a function of its heredity, and that alone makes it worth while to study its genealogy. The history of science is accomplishing an endless purification of scientific facts and ideas. It enables us to deepen them, which is undoubtedly the best way to make them simpler. This simplifica- tion is, of course, the more necessary as science grows bigger and more intricate. By the way, it is thanks to this progressive simplification that an encyclopedic knowledge does not become utterly impossible; in certain cases it becomes even more ac- cessible. For instance, is it not easier to study chemistry or as- tronomy— I mean the essentials of it — now than it was, say, in the fifteenth century? I think one can infer from all the preceding remarks that no scientist is entitled to claim a profound and complete knowledge of his branch of science if he is not acquainted with its history. I HISTORY OF SCIENCE 49 have compared the scientific achievements of mankind with the collective work that the bees accomplish in their hives. This com- parison is particularly apposite to the scientists who have special- ized to excess and work diligently in their own narrow field, ignor- ing the rest of the world. Such men are doubtless necessary, as are the bees that provide honey. But their endeavors could never give birth to a systematic knowledge, to a science proper. It is the more necessary that other scientists raise themselves above the artificial partitions of the different specialties. Their investigations irresist- ibly lead them to the study of history, and they obtain from it a deeper apprehension of their own collaboration in the grand undertakings of mankind. Just as one experiences gratification in knowing where one is and why, similarly it gives them pleasure to locate their own task in the world's work and to grasp better its relative import. And also, they understand, better than others do, the significance of the thousand and one ties that connect them to their fellowmen — and the power of human solidarity, without which there would be no science. THE PEDAGOGIC POINT OF VIEW Science is generally taught in a much too synthetical way.* It may be that this method is indeed the best for the average student who passively accepts the master's authority. But those whose philosophical mind is more awake can hardly be satisfied by this food, the preparation of which is unknown to them. In- stead of being assuaged by harmonious order and perfect science, they are devoured by doubt and anxiety : Why does the master teach us so? Why has he chosen those definitions? Why?" Not that they are loath to use synthetical methods; on the contrary, these young men will probably be the first to admire the depth and elegance of such teaching once they have grasped from their own experience its logical appositeness, its generality and its * My experience refers especially to the European continent and to the teaching of the physical and mathematical sciences. 50 THE LIFE OF SCIENCE economy. But first of all they want to know "how all that was built up/' and their minds instinctively recoil from a dogmatism that is still arbitrary to them. It remains arbitrary indeed so long as the reasons that justify and render natural one arrangement in preference to any other have not been explained. I know that it is not easy to teach be- ginners in this way, but at least the deficiences of the present methods could be tempered, and I do not ask for more. Nothing would be more useful from this point of view than to work out some textbooks in which science would be expounded in chronological order; this is indeed a very important task for which Ernst Mach has given us some admirable models. These textbooks would not be employed for elementary study, unless the pupils used them at the same time as others composed along dogmatic lines. Students should be asked to study the latter and read the former. But in my opinion, these historical textbooks would especially stand professors in good stead, by enabling them to illustrate their lessons and make them more intuitive. Oral teaching, more pliable than written teaching, would easily admit of short historical digressions. Would not the students more easily remember the abstract truths that are impressed upon them in ever-increasing quantities, if their memory could lay hold of some live facts? But that does not exhaust the pedagogic importance of the history of science. Nothing is better fitted to awaken a pupil's critical sense and to test his vocation than to retrace for him in detail the complete history of a discovery, to show him the tram- mels of all kinds that constantly arise in the inventor's path, to show him also how one surmounts them or evades them, and lastly how one draws closer and closer to the goal without ever reaching it. Besides, this historical initiation would cure the young students of the unfortunate habit of thinking that science began with them. Good scientific biographies also have a great educational value; they lead an adolescent's imagination in the best direction. Crit- HISTORY OF SCIENCE 51 ical and sincere biographies make excellent contributions to the history of mankind. Would not the students work with a better heart and more enthusiasm, would they not have a deeper re- spect for science, if they knew a little more about the heroes who have built it up, stone by stone, at the expense of so much suffer- ing, struggle and perseverance? Would they not be more eager to undertake some disinterested research work? Or, at least, would they not better appreciate the greatness and beauty of the whole if they had, more or less, partaken of the joy and intoxication of seeing it accomplished amidst continuous difficulties? Lastly, the history of science — even more than ordinary history — is a general education in itself. It familiarizes us with the ideas of evolution and continuous transformation of human things; it makes us understand the relative and precarious nature of all our knowledge; it sharpens our judgment; it shows us that, if the accomplishments of mankind as a whole are really grand, the contribution of each of us is, in the main, small, and that even the greatest amongst us ought to be modest. It helps to make scientists who are not mere scientists, but also men and citizens. THE PSYCHOLOGICAL AND SOCIOLOGICAL POINTS OF VIEW The history of science, its birth, its evolution, its diffusion, its progress and regressions, irresistibly imposes upon us a series of psychological problems. We here enter the field of "universal history/' such as the much-lamented Karl Lamprecht has defined it; for the history of science in the main amounts to psycho- sociological investigation. It is necessary to make a preliminary distinction. The progress of science is due to two different kinds of causes: (1) Purely psychological causes, the intellectual work of the scientist; (2) Material causes, principally the appearance of new subject matter or the use of improved scientific tools. Of course, it is not difficult to show that the origin of these material causes is itself more or 52 THE LIFE OF SCIENCE less of a psychological nature. But the distinction holds good; a discovery has not the same character, the same psychological im- portance, if it is the almost automatic result of a technical improve- ment, as it would have if it were the fruit of a mind's reaction. We propose to discover the general laws of the intellectual evolution of mankind, if such laws exist. These studies might also help us to better understand the intellect's mechanism. But of course we have given up the extravagant idea of establishing a priori the conditions of scientific development. On the contrary our aim is to deduce them from a thorough analysis of all the accumulated experience of the past. The best instrument for these studies is the comparative method, and this means that we must not expect to reach a degree of accuracy of which this method does not admit. But no scientific work would be possible in the domain of biology and sociology if we did not have the wisdom and patience to be satisfied with the approximation fhat is within our reach. The comparisons may be confined to the realm of science; I would call these the ' 'internal" comparisons. They may also be made between the evolution of scientific phenomena and that of other intellectual or economic phenomena; and these I would call the " external" comparisons. The greatest difficulty, of course, is to find evolutionary processes that can be adequately compared and that are sufficiently inde- pendent one of another. The application of this method has already supplied some re- sults which have been very improperly called "historical laws," and the exactitude of which is very variable. The following are some examples which I list but shall refrain from discussing. Paul Tannery has shown that the development of calculation gener- ally precedes that of geometry. In their choice of decorative ele- ments, primitive peoples always pass from animals to plants; they never do the contrary. The hypothesis that has been expressed about the course of civilization from the South and the East to the North and West, is well known. Remember also the law of his- torical periods proposed by Lamprecht, and especially the famous HISTORY OF SCIENCE 53 law of the three states Qa hi des trois etats) , formulated by Auguste Comte. The theory of historical materialism, originated by Karl Marx, is also a proper example. It is sensible to undertake the study of intellectual activities in the same way that we study the industry of the beavers or the bees. Of the work produced by the human brain we generally know nothing but the results, but these are tangible and can be, if not actually measured, at least compared and appraised with more or less precision. The invention of a machine or the discovery of a natural law: are these not, at bottom, phenomena of the same kind as the behavior of a crab or of a sea anemone under de- termined circumstances? They are, of course, much more com- plex and their study requires the use of new methods, scarcely explored; but can one not admit, at least as a working hypothesis, that they do not differ in essentials? The psychology of the su- perior functions of the brain is not necessarily more complicated than that of the inferior functions; I should be rather inclined to think the contrary. For instance, would it not be easier to retrace the development of a scientific idea in a clear mind than to dis- entangle, in the "pre-logicaf * head of a primitive man, the obscure roots of his instinct of property or imitation? It is from the comparison of these intellectual facts, as they can be collected by the historian of science from the whole intellectual experience of the world, that we may try to deduce the laws of thought. Human experience has been continuously increasing dur- ing the ages, but the intellect itself — has it evolved? The methods of discovery, the mental experiences, the hidden mechanism of intuition — have they not remained somewhat the same? Is there nothing invariable in men's intellectual behavior? What are those invariants, or at least those relative invariants, those more stable parts of ourselves? To what extent does the scientific environment exert its influence upon the scientists, and vice versa"? How do social activities evidence themselves in the domain of science? By what mental processes are the ideas of the initiators integrated in the collective thought, to become, by and by, com- 54 THE LIFE OF SCIENCE mon notions? All these questions, raised by the history of science, are so many psychological problems. As to research concerning the psychology of invention, choice materials will be found in the history of technology. The results of technical invention are material objects of a very concrete and tangible nature. Besides, the mechanism of industrial discoveries is especially interesting, because to materialize his ideas the engineer has actually to struggle with all the difficulties of real life. The struggle is more obvious here than in any other domain. It frequently happens that unexpected obstacles are so great that the idea cannot be carried out; but it also happens very often that the very clash of these obstacles gives birth to new ideas, deeper and richer than the original ones. Then one sees, so to say, the invention gush out from the conflict between matter and spirit. It would be apposite here to present some remarks about the "genealogical" research work that was initiated by Francis Galton and Alphonse de Candolle. These very interesting historico- statistical investigations, intimately connected with the eugenic movement, bring new testimonies to the importance of the history of science from the psycho-sociological point of view. But, in order to give a good idea of these studies, I should be obliged to make too long a digression from my subject. THE HUMANISTIC POINT OF VIEW A deeper knowledge and a greater diffusion of the history of science will help to bring about a new "humanism." (I beg the reader to excuse me for using a word that has already been em- ployed in at least two different senses, but I do not find any other that is more adequate to the idea I wish to convey.) The history of science, if it is understood in a really philosophic way, will broaden our horizon and sympathy; it will raise our intellectual and moral standards; it will deepen our comprehension of men and nature. The humanistic movement of the Renaissance was essentially a synthetic movement. The humanists were longing HISTORY OF SCIENCE 55 for a new atmosphere and a broader conception of life; their curiosity was insatiable. We have at least this much in common with them. We know also that if science were to be abandoned to narrow-minded specialists, it would soon degenerate into a new kind of scholasticism, without life or beauty — false and wrong like death itself. This would be another good reason for comparing our task with that accomplished by the former humanists. How- ever, their movement was essentially toward the past; ours is much more a movement toward the future. Science, divided into water-tight compartments, makes us feel uneasy; — a world split into selfish and quarrelsome nations (simi- lar to the Italian and Flemish municipalities of the Renaissance) is too narrow for us. We need the full experience of other coun- tries, of other races; we need also the full experience of other ages. We need more air! It may be useful to lay some stress on the significance of science from the international point of view. Science is the most precious patrimony of mankind. It is immortal. It is inalienable. It cannot but increase. Does not this precious patrimony deserve to be known thoroughly, not only in its present state but in its whole evolution? Now most men — most scientists — are unfamiliar with the glorious history of our conquests over nature. Would it not be a great work of peace and progress to bring them to better under- standing and appreciation of this intellectual domain which is privileged among all others, because it is the only one that is entirely common to all? Science is not only the strongest tie, but it is the only one that is really strong and undisputed. Science makes for peace more than anything else in the world; it is the cement that holds together the highest and the most com- prehensive minds of all countries, of all races, of all creeds. Every nation derives benefit from the discoveries that have been made by the others. Just as scientific methods are the basis of well-nigh all our knowledge, just so science appears more and more as the bedrock on which every organization has to be built up to be strong and 56 THE LIFE OF SCIENCE fertile. It is the most powerful factor of human progress. As Mach has perfectly put it : cc Science has undertaken to replace wavering and unconscious adaptation by a methodical adaptation, quicker and decidedly conscious/' It is the historian's duty to evidence all the scientific facts and ideas that make for peace and civilization; in this way he will make science's cultural function more secure. The international significance of the history of science has not been better grasped thus far, for the simple reason that very few historical studies have been inspired by a real international spirit. For one thing, universal histories have been almost exclusively devoted to the achievements of the Indo-Aryan race. Everything in them gravitates round the development of Europe. Of course this point of view is absolutely false. The history of mankind is too obviously incomplete if it does not include, on the same level as the Western experience, the immense experience of the East. We badly need the knowledge and wisdom of Asia. They have found other solutions to our own problems (the fundamental problems cannot but be the same) and it is of the greatest importance to consider these solutions, and to consider them with humility. They have very often been nearer to truth and beauty than we. Besides, although the development of the Far Eastern countries has been to a great extent independent of our own, there have been far more exchanges, especially in ancient times, than is generally be- lieved, and it is of paramount importance to investigate these matters. The progress of mankind is not simply an economic develop- ment; it is much more an intellectual unfolding, as Henry Thomas Buckle has shown with so much force. The whole course of civili- zation is marked by the triumph of the mental laws over the physical — a triumph of man over nature. But to my mind, Buckle has even gone too far in this direction. I am not ready to concede his claim that the changes in every civilized people are dependent solely on three things: (1) The amount of knowledge of the ablest men; (2) The direction of this knowledge; (3) Its diffusion. HISTORY OF SCIENCE 57 If Buckle were right all history would be included in the history of science. There are other things to consider. Moral factors do not deserve the contempt which Buckle showed them and I think that it is even possible to construct an ethical interpretation of history. To give a moral significance to history, the essential condition is to make it as complete, as sincere as possible. Nothing is more demoralizing than histories ad usum T)elphini. We must display the whole of human experience, the best and worst together. The greatest achievement of mankind is indeed its struggle against evil and ignorance. Nothing is nobler than this endless struggle between the truth of to-day and that of yesterday. It stands to reason that if one side of the picture is not shown — the evil side, for instance — the other loses a great deal of its interest. The quest for truth and beauty is indeed man's glory. This is certainly the highest moral interpretation which history allows. We must try to humanize science, better to show its various relations with other human activities — its relation to our own nature. It will not lower science; on the contrary, science remains the center of human evolution and its highest goal; to humanize it is not to make it less important, but more significant, more impres- sive, more amiable. The new humanism — as I venture to call the intellectual move- ment that has been defined in the preceding pages — will also have the following consequences : it will disentangle us from many local and national prejudices, also from many of the common prejudices of our own time. Each age has, of course, its own prejudices. Just as the only way to get rid of local prejudices is to travel, — simi- larly, to extricate ourselves from time-narrowness, we must wander through the age?. Our age is not necessarily the best or the wisest, and anyhow it is not the last! We have to prepare the next one, and I hope a better one. If we study history, it is not through mere curiosity, simply to know how things happened in the olden times (if we have no other purpose than this, our knowledge would indeed be of a poor 58 THE LIFE OF SCIENCE quality) ; nor is it for the mere intellectual joy of understanding life better. We are not disinterested enough for that. No; we wish to understand, to foresee more clearly; we wish to be able to act with more precision and wisdom. History itself is of no concern to us. The past does not interest us but for the future. To build up this future, to make it beautiful, as were those glorious times of synthetic knowledge, for instance that of Phidias or of Leonardo da Vinci, it is necessary to prepare a new synthesis. We propose to realize it by bringing about a new and more inti- mate collaboration between scientist, philosopher and historian. If that could be accomplished, it would give birth to so much beauty that the collaboration of the artist would also, necessarily, be secured; an age of synthesis is always an age of art. This syn- thesis is what I call ffthe new humanism." It is something in the making — not a dream. We see it growing, but no one can tell how big it will grow. The writer is convinced that the history of science — that is to say, the history of human thought and civilization in its broadest form — is the indispensable basis of any philosophy. History is but a method — not an aim ! PART TWO SECRET HISTORY 4. SECRET HISTORY The history of mankind is double : political history which is to a large extent a history of the masses, and intellectual history which is largely the history of a few individuals. The first development is the obvious one; it is the one which has thus far claimed the attention of historians almost exclusively. The peoples of the earth and, within each nation, the different classes of men, are not equally fertile, ingenious, energetic, ambi- tious. Their ambition — in the case of peoples one calls it, often, imperialism — is a function of their strength and vitality. If they become conscious of their superiority without being restrained by moral or religious motives, they are bound to become aggres- sive. Between strong, numerous, hungry people on the one hand and a people, weak and few in number, on the other, there arises, so to say, a difference of potential which, if it reaches a certain limit, causes a sudden disruption — war or revolution. Political or economic history can thus be explained in terms of forces chiefly material. (At least in theory, for in most cases the complexity of causes is too great to admit of a strict analysis and we must be con- tent to register most historical disruptions as we register earth- quakes or cyclones : we know the causes but only in a general way, and our grasp of them is very weak.) To be sure, other factors than the material must be considered — moral and religious factors, for instance, — but the fundamental causes are material. Leaders may exert a deep influence and modify the course of events, but only to a limited extent, for their energy remains always a function of the energy of their following. They can lead only to the extent to which they avail themselves of existing passions, of the differences of potential which already obtain: they cannot create these dif- ferences, but they can make use of them in various ways; they can delay the discharge or else provoke it and modify its nature. The second development is far less obvious; in fact so far as the 61 62 THE LIFE OF SCIENCE majority of people is concerned, it is almost secret. Yet it is the development of the activities which are most specifically human, the development of all that is best in humanity: I mean the de- velopment of art, of science, of justice, of moral and religious ideals; in short, the creation and evolution of spiritual values. These values are created by individuals; in most cases isolated individuals. Caesar and Napoleon cannot accomplish their destiny without the collaboration of millions; Spinoza, Newton, Pasteur do accomplish their own in seclusion. They thrive best in solitude. The elaboration of their sacred task — the very fulfillment of human destiny — is to a large degree independent of circumstances. At least, external circumstances seem purely accidental, not really creative. Society can poison Socrates, crucify Jesus or behead Lavoisier; it cannot cause them to be born, it cannot dictate their task. It is a very great pleasure to reveal to young students this second but essential aspect of human history — the course of human progress — for they know generally but little of it, and what they know has been obscured by the large mass of irrelevant and indifferent facts. They see kings enthroned, peoples in arms; they hear the clash of armies or of mobs; they may even hear the impassioned orations of statesmen or rebels. But how could they see the poor philosopher working in his miserable quarters; the artist wrung under the load of his inspiration; the scientist pursu- ing silently, obstinately, his self-imposed quest? It requires more wisdom and imagination than they can possibly have to see these things. They may know pretty well the historical background. It is the inestimable privilege of the historian of science to place in front of it these inconspicuous but central figures. Who cares to know the great business men and the financiers of Greece or Rome or of the Renaissance? Their very names are forgotten. The very few of them who escaped oblivion did so only because they patronized the disinterested activity of schol- ars, artists and scientists. Yet in spite of the high regard which SECRET HISTORY 63 mankind has for those who minister successfully to its material needs, as soon as they are dead and mankind's judgment is no longer influenced by these needs, such men are thrown into the background and their servants — artists and scientists — come into the center of the stage. The sober judgment of mankind thus con- firms our assumption : the few men who enrich its spiritual life are its true representatives in the light of eternity. Are we not right then in believing that it is they, and no others, who fulfill its destiny? This enables us finally to solve another paradox : how can one reconcile the unity of mankind with a chronic state of distrust, of discord and war, alas! all too obvious? Quite simply; the unity is hidden but deep-seated; the disunity widespread but superficial. The unity is felt and expressed primarily by the few men of all nations whose aims are not selfish, or provincial, nationalistic, racial or sectarian in any way, but largely human: the very few men upon whom has devolved the fulfillment of mankind's pur- pose. They realize intensely that their interests are different from the disunity, from the antagonism felt and expressed by an over- whelming majority: those who are jealous of their own brethren: whose contempt, distrust or even hatred of all other men is one of the emotional sources of their life, one of the stimulants of their activity. These strange feelings are reinforced by what little his- torical knowledge they may have. Indeed historical learning and teaching has dealt thus far largely with the most obvious and noisy part of human evolution, but the least important. In spite of many appearances to the contrary, man's essential purpose is not a struggle for existence or for supremacy, not a devastating scramble for the goods of this world, but a generous and fruitful emulation in the creation and the diffusion of spiritual values. Now this creation takes place to a large extent secretly, for it is not accomplished by crowds, nor by pompous dignitaries offici- ating in the eyes of the people, but by individuals often poor and unknown, who carry on their sacred task in mean garrets, in 64 THE LIFE OF SCIENCE wretched laboratories, or in other obscure corners scattered all over the civilized world, with hardly any regard for political boundaries, social or religious distinctions. "The wind bloweth where it listeth." The secrecy of their work is enhanced by the fact that it goes on in spite of the catastrophes, wars and revolu- tions which retain the whole attention of the people. Wars and revolutions are not essentially different from natural catastrophes such as earthquakes, volcanic eruptions, floods or epidemics; they are almost as impersonal and uncontrollable. For most men these catastrophes are by far the most important events, and this is natural enough, since their welfare is dreadfully affected by them. Galileo's or Newton's discoveries do not raise the price of food or shelter, at least not with sufficient suddenness to be per- ceptible. For us, on the contrary, these discoveries which must sooner or later transform man's outlook and, so to say, magnify both the universe and himself, are the cardinal events of the world's history. All the catastrophes, caused either by the untamed forces of nature or by the irrepressible folly of men, are nothing but accidents. They interrupt and upset man's essential activity but, however formidable, they do not and cannot dominate it. 7he essential history of mankind is largely secret. Visible his- tory is nothing but the local scenery, the everchanging and capri- cious background of this invisible history which, alone, is truly ecumenical and progressive. From our point of view, peoples and nations, even as men, are not to be judged by the power or the wealth they have attained, not by the amount of perishable goods which they produce, but only by their imperishable contributions to the whole of humanity. 5. LEONARDO AND THE BIRTH OF MODERN SCIENCE 1 Leonardo da Vinci died in the little manor of Cloux, near Amboise, where he had been for the previous three years the honored guest of Francis I, on May 2, 1519. He was not only one of the greatest artists, but even more the greatest scientist and the greatest engineer of his day. Indeed, with the passing of time his unique personality looms larger and larger and bids fair to attain, as soon as it is completely known, gigantic proportions. Leonardo the artist is so well known that I shall hardly speak of him, but it is worth while for the purpose that I have in mind to recall briefly the most important facts of his life. He was born in Vinci, a village in the hills between Florence and Pisa, in 1452, an illegitimate child, his mother being a peasant woman, and his father Ser Piero, a notary, a man of substance. The latter's family can be traced back to 1 339, through three other generations of notaries. Soon after Leonardo's birth, his father took him away from his mother, and both parents hastened to marry, each in his own set. Ser Piero must have been a man of tremendous vitality, mental and physical. He was one of the most successful notaries of the Signoria and of the great families of Florence, and his wealth increased apace. He married four times, the two first unions remaining childless. His first legitimate child was not born until 1476, when Leonardo was already twenty-four, but after that ten more children were born to him by his third and fourth wives, the last one in the very year of his death, which occurred in 1504, when he was seventy-seven. Thus Leonardo had five mothers. The real one disappears soon after his birth; she bore him and her mission ended there as far as Leonardo was concerned. What the four others were to him, we do not know, for he does not speak of them. He had five mothers and he had none. He is a motherless child, also a brother- less one, because he does not seem to have had much to do with 65 66 THE LIFE OF SCIENCE his eleven brothers and sisters — far younger than himself anyhow — except when, at their father's death, they all leagued them- selves against him to deny him any part of the patrimony. A motherless, brotherless, lonely childhood; we cannot lay too much stress on this; it accounts for so much. In or about 1470 Ser Piero placed his son, now a very handsome and precocious boy, in the studio of Andrea Verrocchio, who since Donatello's death was the greatest sculptor of Florence; also a painter, a goldsmith, a very versatile man, indeed. Within the next years Leonardo had the opportunity to show the stuff of which he was made, and by 1480 his genius had matured. He was considered by common consent a great painter, and, moreover, his mind was swarming with ideas, not simply artistic ideas, but also architectural and engineering plans. Leonardo was born in the neighborhood of Florence and bred in the great city. It is well, even in so short a sketch, to say what this implies. The people of Tuscany are made up of an extraor- dinary mixture of Etruscan, Roman, and Teutonic blood. Their main city, Florence, had been for centuries a considerable em- porium, but also a center of arts and of letters. Suffice it to re- member that of all the Italian dialects it is the Tuscan, and more specifically its Florentine variety, which has become the national language. The prosperous city soon took a lively interest in art, but loved it in its own way. These imaginative but cool-headed merchants patronize goldsmiths, sculptors, draftsmen. They do not waste any sentimentality, neither are they very sensual : clear outlines appeal more to them than gorgeous colors. Except when they are temporarily maddened by personal jealousy or by a feud which spreads like oil, it would be difficult to find people more level-headed, and having on an average more common sense and a clearer will. Leonardo was a Florentine to the backbone, and yet this en- vironment was not congenial to him. He was distinctly superior to most of his fellow citizens as a craftsman, but he could not match the best of them in literary matters. The Medici had gathered LEONARDO AND MODERN SCIENCE 67 around them a circle of men whose delight it was to discuss topics of Greek, Latin, and vernacular literature, and to debate, often in a very learned manner, the subject of Platonic philosophy. There is no gainsaying that these Neoplatonists were a brilliant set of men, but their interests were chiefly of the literary kind; they were men of letters and loved beautiful discourse for its own sake. On the contrary, young Leonardo, following an irresistible trend, was carrying on scientific and technical investigations of every sort. The engineer in him was slowly developing. Perhaps, he could not help considering these amateur philosophers as idle talkers; but it is just as likely that, being a motherless child, he was not endowed with sufficient urbanity to fare comfortably in this society of refined dilettanti. Nature more and more engrossed his attention, and he was far more deeply concerned in solving its innumerable problems than in trying to reconcile Platonism and Christianity. Neither could his brother artists satisfy his intel- lectual needs; they were talking shop and fretting all the time. A few had shown some interest in scientific matters, but on the whole their horizon was too narrow and their self-centeredness un- bearable. Also, Florence was becoming a very old place, and an overgrowth of traditions and conventions gradually crowded out all initiative and real originality. So Leonardo left and went to Milan, to the court of Ludovico Sforza, at that time one of the most splendid courts of Europe. Milan would certainly offer more opportunities to an enterprising and restless mind like his. The very desire of outdoing Florence was a tremendous impulse for Ludovico: he was anxious to make of his capital a new Athens, and of the near-by university town of Pavia a great cultural center. His happiest thought perhaps was to keep around him two men who were among the greatest of their day — Bramante and Leonardo. The liberal opportunities which were offered to these two giants are the supreme glory of the Sforzas and of Milan. Leonardo was employed by the Duke as a civil and military engineer, as a pageant master, as a sculptor, as a painter, as an architect. How far he was understood by his patron it is difficult 68 THE LIFE OF SCIENCE to say. But he seems to have thrived in this new atmosphere, and these Milanese years are among the most active and the most fertile of his life. He was now at the height of his power and full scope was given to his devouring activity. It is during this period, for instance, that he modelled his famous equestrian statue of Francesco Sforza, that he painted the "Virgin of the Rocks/' and the "Last Supper/' while he was also superintending important hydraulic works, and pursuing indefatigably his various scientific investigations. Yet even at this time of greatest activity and en- thusiasm he must have been a lonesome man. This brilliant but very corrupt court was of course the rendezvous of hundreds of dilettanti, parasites, snobs — male and female — and what could Leonardo do to protect himself against them but be silent and withdraw into his own shell? Milan justly shares with Florence the fame of having given Leonardo to the world; it was really his second birthplace. Un- fortunately, before long, heavy clouds gathered over this joyous city, and by 1 500 the show was over and Ludovico, made prisoner by the French, was to spend the last ten years of his life most miserably in the underground cell of a dungeon. From that time on, Leonardo's life became very unsettled. It is true, he spent many years in Florence, employed by the Signoria, painting "la Gioconda" and the "Battle of Anghiari"; then for some years he was back in Milan, but he is more and more restless and some- how the charm is broken. After the fall of the Sforzas, Isabella d'Este, Marchioness of Mantua — perhaps the most distinguished woman of the Renaissance — tried to attach Leonardo to he*" serv- ice, but he refused, and instead he chose, in 1502, to follow Cesare Borgia as his military engineer. One may wonder at this choice, yet it is easy enough to explain. At that time Leonardo was already far prouder of his achievements as a mechanic and an engineer than as a painter. It is likely that in the eyes of Isabella, however, he was simply an artist and he may have feared that this accom- plished princess would give him but little scope for his engineering designs and his scientific research. On the other hand, Leonardo LEONARDO AND MODERN SCIENCE 69 found himself less and less at home in Florence. The city had con- siderably changed in the last ten years. Savonarola had ruled it, and many of the artists had been deeply swayed by his passionate appeals, and even more by his death. For once, fair Florence had lost her head. And then also, young Michael Angelo had appeared, heroic but intolerant and immoderate: he and Leonardo were equally great but so different that they could not possibly get on together. In 1513-15 Leonardo went to the papal court, but there, for the first time in his life, the old man was snubbed. Having left Rome, his prospects were getting darker, when fortunately he met in Bologna the young King of France, Francis I, who persuaded him to accept his patronage. The King offered him a little castle in Touraine, with a princely income, and there Leonardo spent in comparative quietness, the last three years of his life. It must be said to the credit of Francis I that he seems to have understood his guest, or at least to have divined his sterling worth. France, how- ever, did not appreciate Leonardo, and was not faithful to her trust. The cloister of Saint-Florentin at Amboise, where the great artist had been buried, was destroyed by a fire in 1808, and his very ashes are lost. He was apparently an old man when he died, much older than his years, exhausted by his relentless mind and by the vicissitudes and the miseries of his strange career. Only those who have known suffering and anxiety can fully understand the drama and the beauty of his life. Throughout his existence Leonardo had carried on simultane- ously, and almost without a break, his work as an artist, as a scientist, as an engineer. Such a diversity of gifts was not as un- usual in his day as it would be now. Paolo Uccello, Leo B. Alberti, Piero dei Franceschi, even Verrocchio himself, had shown more than a casual interest in scientific matters such as perspective and anatomy, but Leonardo towers far above them. The excellence of his endowment is far more amazing than its complexity. His 70 THE LIFE OF SCIENCE curiosity was universal to such a degree that to write a complete study of his genius amounts to writing a real encyclopaedia of fifteenth-century science and technology. From his earliest age he had given proofs of this insatiable thirst for knowledge. He could take nothing for granted. Everything that he saw, either in the fields or on the moving surface of a river, or in the sky, or in the bottega of his master, or in the workshops of Florence, raised a new problem in his mind. Most of the time neither man nor book could give an answer to his question, and his mind kept working on it and remained restless until he had devised one himself. This means, of course, that there was no rest for him until the end. In a few cases, however, a satisfactory answer suggested itself, and so a v/hole system of knowledge was slowly unfolding in him. His apprenticeship in Verrocchio's studio must have greatly fostered his inquiries in the theory of perspective, the art of light and shade, and the physiology of vision; the preparation of colors and varnishes must have turned his thoughts to chemistry; while the routine of his work woke up naturally enough his interest in anatomy. He could not long be satisfied by the study of the so- called artistic anatomy, which deals only with the exterior muscles. For one thing, the study of the movements of the human figure, which he tried to express in his drawings, raised innumer- able questions: how were they possible, what kept the human machine moving and how did it work? ... It is easy to imagine how he was irresistibly driven step by step to investigate every anatomical and physiological problem. There are in the King's library at Windsor hundreds of drawings of his which prove that he made a thorough analysis of practically all the organs. Indeed, he had dissected quite a number of bodies, in- cluding that of a gravid woman, and his minute and compre- hensive sketches are the first anatomical drawings worthy of the name. Many of these sketches are devoted to the comparison of human anatomy with the anatomy of animals, the monkey or the horse for instance; or else he will compare similar parts of various animals, say, the eyes or a leg and a wing. Other sketches relate LEONARDO AND MODERN SCIENCE 71 to pathological anatomy: the hardening of the arteries; tubercu- lous lesions of the lungs; a very searching study of the symptoms of senility. On the other hand his activity as a practical engineer led him to study, or we might almost say to found, geology: he set to wonder at the various layers of sand and clay which the cutting of a canal did not fail to display; he tried to explain the fossils which he found embedded in the rocks and his explanations were sub- stantially correct. Moreover, he clearly perceived the extreme slowness of most geological transformations, and figured that the alluvial deposits of the river Po were two hundred thousand years old. He well understood the geological action of water and its meteorological cycle. His work as a sculptor, or as a military engineer (for instance, when he had to supervise the casting of bombards) , caused him to study metallurgy, particularly the smelting and casting of bronze, the rolling, drawing, planing, and drilling of iron. On all these subjects he has left elaborate instructions and drawings. He undertook in various parts of northern Italy a vast amount of hydraulic work : digging of canals, for which he devised a whole range of excavating machines and tools; building of sluices; estab- lishment of water wheels and pipes, and his study of hydro- dynamics was so continuous that notes referring to it are found in all his manuscripts. He also studied the tides, but did not under- stand them. In fact, it is impossible to give even a superficial account of all his scientific and technical investigations, and the reader must for- give me if the magnitude of the subject obliges me to limit myself to a sort of catalogue, for the adequate development of any single point would take many a page. Leonardo's manuscripts contain a great number of architectural drawings, sketches of churches and other buildings, but also more technical matters; he studied the proportion of arches, the construction of bridges and staircases; how to repair fissures in walls; how to lift up and move houses and churches. There is also much of what we would call town- 72 THE LIFE OF SCIENCE planning; the plague of Milan in 1484 likely was his great oppor- tunity in this field, and he thought of various schemes to improve public sanitation and convenience, including a two-level system of streets. Botany repeatedly fixed his attention and we find many notes on the life of plants, the mathematical distribution of leaves on a stem, also beautiful and characteristic drawings of various species. A great deal of the work undertaken for his employers was of course connected with military engineering: hundreds of notes and sketches on all sorts of arms and armor, on all imagin- able offensive and defensive appliances; of course, many plans for fortifications and strongholds (how to attack them and how to defend them); portable bridges; mining and countermining; tanks; various devices for the use of liquid fire, or of poisoning and asphyxiating fumes. He adds occasional notes on military and naval operations. He had even thought of some kind of submarine apparatus, by means of which ships could be sunk, but the dastardliness of the idea had horrified and stopped him. No field, however, could offer a fuller scope to his prodigious versatility and ingenuity than the one of practical mechanics. A very intense industrial development had taken place in Tuscany and Lombardy for centuries before Leonardo's birth; the pros- perity of their workshops was greater than ever; there was a con- tinuous demand for inventions of all kinds, and no environment was more proper to enhance his mechanical genius. Leonardo was a born mechanic. He had a deep understanding of the elementary parts of which any machine, however compli- cated, is made up, and his keen sense of proportions stood him in good stead when he started to build it. He devised machines for almost every purpose which could be thought of in his day. I quote a few examples at random : various types of lathes; machines to shear cloth; automatic file-cutting machines; sprocket wheels and chains for power transmission; machines to saw marble, to raise water, to grind plane and concave mirrors, to dive under water, to lift up, to heat, to light; paddle-wheels to move boats. And mind you, Leonardo was never satisfied with the applications LEONARDO AND MODERN SCIENCE 73 alone, he wanted to understand as thoroughly as possible the prin- ciples underlying them. He clearly saw that practice and theory are twin sisters who must develop together, that theory without practice is senseless, and practice without theory hopeless. So it was not enough for him to hit upon a contrivance which answered his purpose; he wanted to know the cause of his success, or, as the case may be, of his failure. That is how we find in his papers the earliest systematic researches on such subjects as the stability of structures, the strength of materials, also on friction which he tried in various ways to overcome. That is not all: he seems to have grasped the principle of automaticity — that a machine is so much the more efficient, that it is more continuous and more in- dependent of human attention. He had even conceived, in a special case, a judicious saving of human labor, that is, what we now call "scientific management." His greatest achievement in the field of mechanics, however, and one which would be sufficient in itself to prove his extraor- dinary genius, is his exhaustive study of the problem of flying. It is complete, in so far that it would have been impossible to go further at his time, or indeed at any time until the progress of the automobile industry had developed a suitable motor. These inves- tigations which occupied Leonardo throughout his life, were of two kinds. First, a study of the natural flying of birds and bats, and of the structure and function of their wings. He most clearly saw that the bird obtains from the air the recoil and the resistance which is necessary to elevate and carry itself forward. He ob- served how birds took advantage of the wind and how they used their wings, tails, and heads as propellers, balancers and rudders. In the second place, a mechanical study of various kinds of arti- ficial wings, and of diverse apparatus by means of which a man might move them, using for instance the potential energy of springs, and others which he would employ to equilibrate his ma- chine and steer its course. It is necessary to insist that most of these drawings and notes of Leonardo's are not idle schemes, vague and easy sugaesffonsV 7 74 THE LIFE OF SCIENCE such as we find, for instance, in the writings of Roger Bacon; but, on the contrary, very definite and clear ideas which could have been patented, if such a thing as a patent office had already existed! Moreover, a number of these drawings are so elaborate, giving us general views of the whole machine from different direc- tions, and minute sketches of every single piece and of every detail of importance — that it would be easy enough to reconstruct it. In many cases, however, that is not even necessary, since these machines were actually constructed and used, some of them almost to our own time. To visualize better the activity of his mind, let us take at ran- dom a few years of his life and watch him at work. We might take, for instance, those years of divine inspiration when he was painting the "Last Supper" in the refectory of Santa Maria delle Grazie, that is, about 1494-98. Do you suppose that this vast undertaking claimed the whole of his attention? During these few years we see him act professionally as a pageant master, a decorator, an architect, an hydraulic engineer. His friend, Fra Luca Pacioli, the mathematician, tells us that by 1498 Leonardo "had completed with the greatest care his book on painting and on the movements of the human figure." We also know that before 1499, he had painted the portraits of Cecilia Gallerani and of Lucrezia Crivelli. Besides, his note-books of that period show that he was interested in a great variety of other subjects, chief among them hydraulics, flying, optics, dynamics, zoology, and the construction of various machines. He was also making a study of his own language, and preparing a sort of Italian dictionary. No wonder that the prior of Santa Maria com- plained of his slowness! It so happened that during these four years he did not do much anatomical work, but during almost any other period he would have been carrying on some dissecting. Corpses were always hard to get, and I suppose that when he could get hold of one he made the most of it, working day and night as fast as he could. Then, LEONARDO AND MODERN SCIENCE 75 as a change, he would go out into the fields and gaze at the stars, or at the earthshine which he could see inside the crescent of the moon; or else, if it were daytime, he would pick up fossils or marvel at the regularities of plant structure, or watch chicks break- ing their shells. . . . Was it not uncanny? Fortunate was he to be born at a time of relative toleration. If he had appeared a cen- tury later, when religious fanaticism had been awakened, be sure this immoderate curiosity would have led him straight to the stake. But remarkable as Leonardo's universality is, his earnestness and thoroughness are even more so. There is not a bit of dilet- tantism in him. If a problem has once arrested his attention, he will come back to it year after year. In some cases, we can actually follow his experiments and the hesitations and slow progress of his mind for a period of more than twenty-five years. That is not the least fascinating side of his notes; as he wrote them for his own private use, it is almost as if we heard him think, as if we were admitted to the secret laboratory where his discoveries were slowly maturing. Such an opportunity is unique in the history of science. Just try to realize what it means : Here we have a man of con- siderable mother-wit, but unlearned, unsophisticated, who had to take up every question at the very beginning, like a child. Leonardo opened his eyes and looked straight upon the world. There were no books between nature and him; he was untram- melled by learning, prejudice, or convention. He just asked him- self questions, made experiments and used his common sense. The world was one to him, and so was science, and so was art. But he did not lose himself in sterile contemplation, or in verbal gen- eralities. He tried to solve patiently each little problem separately. He saw that the only fruitful way of doing that is first to state the problem as clearly as possible, then to isolate it, to make the neces- sary experiments and to discuss them. Experiment is always at the bottom; mathematics, that is, reason, at the end. In short, the method of inductive philosophy which Francis Bacon was to ex- 76 THE LIFE OF SCIENCE plain so well a century and a half later, Leonardo actually prac- ticed. This is, indeed, his greatest contribution: his method. He deeply realized that if we are to know something of this world, we can know it only by patient observation and tireless experi- ment. His note-books are just full of experiments and experimental suggestions, 'Try this ... do that . . ." and we find also whole series of experiments, wherein one condition and then another are gradually varied. Now, that may seem of little account, yet it is everything. We can count on our fingers the men who devised real experiments before Leonardo, and these experiments are very few in number and very simple. But perhaps the best way to show how far he stood on the road to progress, is to consider his attitude in regard to the many super- stitions to which even the noblest and most emancipated minds of his day paid homage, and which were to sway Europe for more than two centuries after Leonardo's death. Just remember that in 1484, the Pope Boniface VIII had sown the seed of the witch mania, and that this terrible madness was slowly incubating at the time of which we are speaking. Now, Leonardo's contempt for astrologers and alchemists was most outspoken and unconditional. He met the spiritists of his age, as we do those of to-day, by simply placing the burden of proof on their shoulders. It is true, for all these matters, his Florentine ancestry stood him in good stead. Petrarca had already shown how Florentine common sense disposed of them; but Petrarca, man of letters, would not have dared to treat* the believers in ghosts, the medical quacks, the necromancers, the searchers for gold and for perpetual motion as one bunch of impostors. And that is what Leonardo did repeatedly and most decidedly. Oh! how they must have liked him! I must insist on this point: it is his ignorance which saved Leonardo. I do not mean to say that he was entirely unlearned, but he was sufficiently unlearned to be untrammelled. However much he may have read in his mature years, I am convinced that LEONARDO AND MODERN SCIENCE 77 the literary studies of his youth were very poor. No teachers had time to mould his mind and to pervert his judgment. The good workman Verrocchio was perhaps his first philosopher, nature herself his real teacher. He was bred upon the experiments of the studio and of real life, not upon the artificialities of a mediaeval library. He read more, later in life, but even then his readings, I think, were never exhaustive. He was far too original, too im- patient. If he began to read, some idea would soon cross his mind, and divert his attention, and the book would be abandoned. Any- how, at that time his mind was already proof against the scholastic fallacies; he was able, so to say, to filter through his own experi- ence whatever mediaeval philosophy reached him either in print or by word of mouth. Neither do I mean to imply that all the schoolmen were dunces. Far from that, not a few were men of amazing genius, but their point of view was never free from prejudice; it was always the theological or legal point of view; they were always like lawyers pleading a cause; they were constitutionally unable to investigate a problem without reservation and without fear. Moreover, they were so cocksure, so dogmatic. Their world was a limited, a closed system; had they not encompassed and exhausted it in their learned encyclopaedias? In fact they knew everything except their own ignorance. Now the fact that Leonardo had been protected against them by his innocence is of course insufficient to account for his genius. Innocence is but a negative quality. Leonardo came to be what he was because he combined in himself a keen and candid intelli- gence with great technical experience and unusual craftsmanship. That is the very key to the mystery. Maybe if he had been simply a theoretical physicist, as were many of the schoolmen (their interest in astronomy and physics was intense), he would not have engaged in so many experiments. But as an engineer, a mechanic, a craftsman, he was experimenting all the while; he could not help it. If he had not experimented on nature, nature would have experimented on him; it was only a choice between 78 THE LIFE OF SCIENCE offensive and defensive experimenting. Anyhow, whether he chose to take the initiative or not, these experiments were the fountainhead of his genius. To be sure, he had also a genuine in- terest in science, and the practical problems which he encountered progressively allured him to study it for its own sake, but that took time : once more the craftsman was the father of the scientist. I would not have the reader believe that everything was wrong and dark in the Middle Ages. This childish view has long been exploded. The most wonderful craftsmanship inspired by noble ideals was the great redeeming feature of that period — unfortu- nately never applied outside the realm of religion and of beauty. The love of truth did not exalt mediaeval craftsmen, and it is un- likely that the thought of placing his art at the service of truth ever occurred to any of them. Now, one does not understand the Renaissance if one fails to see that the revolution — I almost wrote, the miracle — which hap- pened at that time was essentially the application of this spirit of craftsmanship and experiment to the quest of truth, its sudden ex- tension from the realm of beauty to the realm of science. That is exactly what Leonardo and his fellow investigators did. And there and then modern science was born, but unfortunately Leo- nardo remained silent, and its prophets came only a century later. . . . Man has not yet found a better way to be truly original than to go back to nature and to disclose one of her secrets. The Renaissance would not have been a real revolution, if it had been simply a going back to the ancients; it was far more, it was a return to nature. The world, hitherto closed-in and pretty as the garden of a beguinage, suddenly opened into infinity. It gradu- ally occurred to the people — to only very few at first — that the world was not closed and limited, but unlimited, living, forever becoming. The whole perspective of knowledge was upset, and as a natural consequence all moral and social values were trans- LEONARDO AND MODERN SCIENCE 79 muted. The humanists had paved the way, for the discovery of the classics had sharpened the critical sense of man, but the revo- lution itself could only be accomplished by the experimental philosophers. It is clear that the spirit of individuality, which is so often claimed to be the chief characteristic of this movement, is only one aspect of the experimental attitude. It may seem strange that this technical basis of the Renaissance has been constantly overlooked, but that is simply due to the fact that our historians are literary people, having no interest what- ever in craftsmanship. Even in art it is the idea and the ultimate result, not the process and the technique which engross their attention. Many of them look upon any kind of handicraft as something menial. Of course, this narrow view makes it impos- sible for them to grasp the essential unity of thought and tech- nique, or of science and art. The scope of abstract thinking is very limited; if it be not constantly rejuvenated by contact with nature our mind soon turns in a circle and works in a vacuum. The fun- damental vice of the schoolmen was their inability to avow that, however rich experimental premises may be, their contents are limited/ — and there is no magic by means of which it is possible to extract from them more than they contain. The fact that Leonardo's main contribution is the introduction, not of a system, but rather of a method, a point of view, caused his influence to be restricted to the few people who were not im- pervious to it. Of course, at almost any period of the past there have been some people — only a very few — who did not need any initiation to understand the experimental point of view, because their souls were naturally oriented in the right way. These men form, so to say, one great intellectual family: Aristotle, Archi- medes, Ptolemy, Galen, Roger Bacon, Leonardo, Stevin, Gilbert, Galileo, Huygens, Newton. . . . They hardly need any incentive; they are all right anyhow. However, Leonardo's influence was even more restricted than theirs, because he could never prevail upon himself to publish the results of his experiments and meditations. 80 THE LIFE OF SCIENCE His notes show that he could occasionally write in a terse lan- guage and with a felicity of expression which would be a credit to any writer; but somehow he lacked that particular kind of moral energy which is necessary for a long composition, or he was per- haps inhibited, as so many scientists are, by his exacting ideal of accuracy. All that we know of Leonardo's scientific activities is patiently dug out of his manuscripts. He was left-handed and wrote left- handedly, that is, in mirror- writing : his writing is like the image of ours in a mirror. It is a clear hand, but the disorder of the text is such that the reading is very painful. Leonardo jumps from one subject to another; the same page may contain remarks on dy- namics, on astronomy, an anatomical sketch, and perhaps a draft and calculations for a machine. The study of Dante is in many ways far simpler. His scientific lore does not begin to compare with Leonardo's knowledge. The T)ivina Commedia is the sublime apotheosis of the Middle Ages; Leonardo's note-books are not simply an epitome of the past, but they contain to a large extent the seeds of the future. The world of Dante was the closed mediaeval world; the world of Leonardo is already the unlimited world of modern man : the immense vision which it opens is not simply one of beauty, of implicit faith, and of corresponding hope; it is a vision of truth, truth in the making. It is perhaps less pleasant, less hopeful; it does not even try to please, nor to give hope; it just tries to show things as they are: it is far more mysterious, and incomparably greater. I do not mean to say that Dante had not loved truth, but he had loved it like a bashful suitor. Leonardo was like a con- quering hero; his was not a passive love, but a devouring passion, an indefatigable and self-denying quest, to which his life and per- sonal happiness were entirely sacrificed. Some literary people who do not realize what this quest implies, have said that he was selfish. It is true, he took no interest in the petty and hopeless political struggles of his day; Savonarola's revival hardly moved him, and he had no more use for religious charlatanry than for scientific LEONARDO AND MODERN SCIENCE 81 quackery. One would be a poor man, however, who would not recognize at once in Leonardo's aphorisms a genuine religious feeling, that is, a deep sense of brotherhood and unity. His gen- erosity, his spirit of detachment, even his melancholy, are un- mistakable signs of true nobility. (He often makes me think of Pascal.) He was very lonely, of course, from his own choice, be- cause he needed time and quietness, but also because, being so utterly different, it is easy to conceive that many did not like him. I find it hard to believe that he was very genial, in spite of what Vasari says. Being surrounded by people whose moral standards were rather low or, if these were higher, who were apt to lose their balance and to become hysterical because of their lack of knowl- edge, Leonardo's solitude could but increase, and to protect his equanimity he was obliged to envelop himself in a triple veil of patience, kindness, and irony. Leonardo's greatest contribution was his method, his attitude; his masterpiece was his life. I have heard people foolishly regret that his insatiable curiosity had diverted him from his work as a painter. In the spiritual sphere it is only quality that matters. If he had painted more and roamed less along untrodden paths, his paintings perhaps would not have taught us more than do those of his Milanese disciples. While, even as they stand now, scarce and partly destroyed, they deliver to us a message which is so un- compromisingly high that even to-day but few understand it. Let us listen to it; it is worth while. This message is as pertinent and as urgent to-day as it was more than four hundred years ago. And should it not have become more convincing because of all the dis- coveries which have been made in the meanwhile? Do I dream, or do I actually hear, across these four centuries, Leonardo whisper: To know is to love. Our first duty is to know. These people who always call me a painter annoy me. Of course, I was a painter, but I was also an engineer, a mechanic. N4y life was one long struggle with nature, to unravel her secrets and tame her wild forces to the purpose of man. They laughed at me because I was 82 THE LIFE OF SCIENCE unlettered and slow of speech. Was I? Let me tell you: a literary education is no education. All the classics of the past cannot make men. Experience does, life does. They are rotten with learning and understand nothing. Why do they lie to themselves? How can they keep on living in the shade of knowledge, without com- ing out in the sun? How can they be satisfied with so little — when there is so much to be known, so much to be admired? . . . They love beauty, so they say — but beauty without truth is noth- ing but poison. Why do they not interrogate nature? Must we not first understand the laws of nature, and only then the laws and the conventionalities of men? Should we not give more im- portance to that which is most permanent? The study of nature is the substance of education — the rest is only the ornament. Study it with your brains and with your hands. Do not be afraid to touch her. Those who fear to experiment with their hands will never know anything. We must all be craftsmen of some kind. Honest craftsmanship is the hope of the world. . . ." 6. EVARISTE GALOIS No episode in the history of thought is more moving than the life of Evariste Galois — the young Frenchman who passed like a meteor about 1828, devoted a few feverish years to the most in- tense meditation, and died in 1832 from a wound received in a duel, at the age of twenty. He was still a mere boy, yet within these short years he had accomplished enough to prove indubi- tably that he was one of the greatest mathematicians of all time. When one sees how terribly fast this ardent soul, this wretched and tormented heart, were consumed, one can but think of the beautiful meteoric showers of a summer night. But this comparison is misleading, for the soul of Galois will burn on throughout the ages and be a perpetual flame of inspiration. His fame is incor- ruptible; indeed the apotheosis will become more and more splendid with the gradual increase of human knowledge. No existence could be more tragic than his and the only one at all comparable to it is, strangely enough, that of another mathematician, fully his equal, the Norwegian Niels Henrik Abel, who died of consumption at twenty-six in 1829; that is, just when Galois was ready to take the torch from his hand and to run with it a little further. Abel had the inestimable privilege of living six years longer, and think of these years — not ordinary years of a humdrum existence, but six full years at the time that genius was ripe — six years of divine inspiration! What would not Galois have given us, if he had been granted six more such years at the climax of his life? But it is futile to ask such questions. Prophecies too are futile, yet a certain amount of anticipation of the future may be allowed, if one does not contravene the experience of the past. For example, it is safe to predict that Galois' fame can but wax, be- cause of the fundamental nature of his work. While the inventors of important applications, whose practical value is obvious, re- ceive quick recognition and often very substantial rewards, the 83 84 THE LIFE OF SCIENCE discoverers of fundamental principles are not generally awarded much recompense. They often die misunderstood and unre- warded. But while the fame of the former is bound to wane as new processes supersede their own, the fame of the latter can but increase. Indeed the importance of each principle grows with the number and the value of its applications; for each new application is a new tribute to its worth. To put it more concretely, when we are very thirsty a juicy orange is more precious to us than an orange tree. Yet when the emergency has passed, we learn to value the tree more than any of its fruits; for each orange is an end in itself, while the tree represents the innumerable oranges of the future. The fame of Galois has a similar foundation; it is based upon the unlimited future. He well knew the pregnancy of his thoughts, yet they were even more far-reaching than he could possibly dream of. His complete works fill only sixty-one small pages: but a French geometer, publishing a large volume some forty years after Galois' death, declared that it was simply a com- mentary on the latter's discoveries. Since then, many more conse- quences have been deduced from Galois' fundamental ideas which have influenced the whole of mathematical philosophy. It is likely that when mathematicians of the future contemplate his personality at the distance of a few centuries, it will appear to them to be surrounded by the same halo of winder as those of Euclid, Archimedes, Descartes and Newton. Evariste Galois was born in Bourg-la-Reine, near Paris, on the 25th of October, 1811 in the very house in which his grandfather had lived and had founded a boys' school. This being one of the very few boarding schools not in the hands of the priests, the Revolution had much increased its prosperity. In the course of time, grandfather Galois had given it up to his younger son and soon after, the school had received from the imperial government a sort of official recognition. When Evariste was born, his father was thirty-six years of age. He had remained a real man of the eighteenth century, amiable and witty, clever at rhyming verses and writing playlets, and instinct with philosophy. He was the EVARISTE GALOIS 85 leader of liberalism in Bourg-la-Reine, and during the Hundred Days had been appointed its mayor. Strangely enough, after Waterloo he was still the mayor of the village. He took his oath to the King, and to be sure he kept it, yet he remained a liberal to the end of his days. One of his friends and neighbours, Thomas Francois Demante, a lawyer and judge, onetime professor in the Faculty of Law of Paris, was also a typical gentleman of the "ancien regime/' but of a different style. He had given a very solid classical education not only to his sons but also to his daughters. None of these had been more deeply imbued with the examples of antiquity than Adelaide-Marie who was to be Evariste's mother. Roman stoicism had sunk deep into her heart and given to it a virile temper. She was a good Christian, though more concerned with the ethical than with the mystical side of religion. An ardent imagination had colored her every virtue with passion. Many more people have been able to appreciate her char- acter than her son's, for it was to be her sad fortune to survive him forty years. She was said to be generous to a fault and original to the point of queerness. There is no doubt that Evariste owed con- siderably more to her than to his father. Besides, until the age of eleven the little boy had no teacher but his mother. In 1823, Evariste was sent to college in Paris. This college — Louis-le-Grand — was then a gloomy house, looking from the out- side like a prison, but within aflame with life and passion. For heroic memories of the Revolution and the Empire had remained particularly vivid in this institution, which was indeed, under the clerical and reactionary regime of the Restoration, a hot-bed of liberalism. Love of learning and contempt of the Bourbons divided the hearts of the scholars. Since 1815 the discipline had been jeopardized over and over again by boyish rebellions, and Evariste was certainly a witness of, if not a partner in, those which took place soon after his arrival. The influence of such an impassioned atmosphere upon a lad freshly emancipated from his mother's care cannot be exaggerated. Nothing is more infectious than political 86 THE LIFE OF SCIENCE passion, nothing more intoxicating than the love of freedom. It was certainly there and then that Evariste received his political initiation. It was the first crisis of his childhood. At first he was a good student; it was only after a couple of years that his disgust at the regular studies became apparent. He was then in the second class (that is, the highest but one) and the headmaster suggested to his father that he should spend a second year in it, arguing that the boy's weak health and immaturity made it imperative. The child was not strong, but the headmaster had failed to discover the true source of his lassitude. His seem- ing indifference was due less to immaturity than to his mathe- matical precocity. He had read his books of geometry as easily as a novel, and the knowledge had remained firmly anchored in his mind. No sooner had he begun to study algebra than he read Lagrange's original memoirs. This extraordinary facility had been at first a revelation to himself, but as he grew more conscious of it, it became more difficult for him to curb his own domineering thought and to sacrifice it to the routine of class work. The rigid program of the college was to him like a bed of Procrustes, caus- ing him unbearable torture without adequate compensation. But how could the headmaster and the teachers understand this? The double conflict within the child's mind and between the teachers and himself, as the knowledge of his power increased, was in- tensely dramatic. By 1827 it had reached a critical point. This might be called the second crisis of his childhood : his scientific initiation. His change of mood was observed by the family. Juvenile gaiety was suddenly replaced by concentration; his manners became stranger every day. A mad desire to march for- ward along the solitary path which he saw so distinctly, possessed him. His whole being, his every faculty was mobilized in this immense endeavor. I cannot give a more vivid idea of the growing strife between this inspired boy and his uninspired teachers than by quoting a few extracts from the school reports : EVARISTE GALOIS 87 1826-1827 This pupil, though a little queer in his manners, is very gentle and seems filled with innocence and good qualities. . . . He never knows a lesson badly: either he has not learned it at all or he knows it well. . . . A little later: This pupil, except for the last fortnight during which he has worked a little, has done his classwork only from fear of punish- ment. . . . His ambition, his originality — often affected — the queerness of his character keep him»aloof from his companions. 1827-1828 Conduct rather good. A few thoughtless acts. Character of which I do not flatter myself I understand every trait; but I see a great deal of self-esteem dominating. I do not think he has any vicious inclination. His ability seems to me to be entirely beyond the aver- age, with regard as much to literary studies as to mathematics. . . . He does not seem to lack religious feeling. His health is good but delicate. Another professor says: His facility, in which one is supposed to believe but of which I have not yet witnessed a single proof, will lead him nowhere: there is no trace in his tasks of anything but of queerness and negligence. Another still: Always busy with things which are not his business. Goes down every day. Same year, but a little later : Very bad conduct. Character rather secretive. Tries to be original. . . . Does absolutely nothing for the class. The furor of mathematics possesses him. ... He is losing his time here and does nothing but 88 THE LIFE OF SCIENCE torment his masters and get himself harassed with punishments. He does not lack religious feeling; his health seems weak. Later still : Bad conduct, character difficult to define. Aims at originality. His talents are very distinguished; he might have done very well in "Rhetorique" if he had been willing to work, but swayed by his passion for mathematics, he has entirely neglected everything else. Hence he has made no progress whatever. . . . Seems to affect to do something different from what he should do. It is pos- sibly to this purpose that he chatters so much. He protests against silence. In his last year at the college, 1828-1829, he had at last found a teacher of mathematics who divined his genius and tried to en- courage and to help him. This Mr. Richard, to whom one cannot be too grateful, wrote of him : "This student has a marked superi- ority over all his schoolmates. He works only at the highest parts of mathematics/' You see the whole difference. Kind Mr. Richard did not complain that Evariste neglected his regular tasks, and, I imagine, often forgot to do the petty mathematical exercises which are indispensable to drill the average boy; he does not think it fair to insist on what Evariste does not do, but states what he does do : he is only concerned with the highest parts of mathematics. Unfor- tunately, the other teachers were less indulgent. For physics and chemistry, the note often repeated was : "Very absent-minded, no work whatever." To show the sort of preoccupations which engrossed his mind: at the age of sixteen he believed that he had found a method of solving general equations of the fifth degree. One knows that be- fore succeeding in proving the impossibility of such resolution, Abel had made the same mistake. Besides, Galois was already try- ing to realize the great dream of his boyhood : to enter the Ecole Polytechnique. He was bold enough to prepare himself alone for the entrance examination as early as 1 828 — but failed. This failure was very bitter to him — the more so that he considered it as un- EVARISTE GALOIS 89 fair. It is likely that it was not at all unfair, at least according to the accepted rules. Galois knew at one and the same time far more and far less than was necessary to enter Polytechnique; his extra knowl- edge could not compensate for his deficiencies, and examiners will never consider originality with favor. The next year he published his first paper, and sent his first communication to the Academie des Sciences. Unfortunately, the latter got lost through Cauchy's negligence. This embittered Galois even more. A second failure to enter Polytechnique seemed to be the climax of his misfortune, but a greater disaster was still in store for him. On July 7 of this same year, 1829, his father had been driven to commit suicide by the vicious attacks directed against him, the liberal mayor, by his po- litical enemies. He took his life in the small apartment which he had in Paris, in the vicinity of Louis-le-Grand. As soon as his father's body reached the territory of Bourg-la-Reine, the inhabi- tants carried it on their shoulders, and the funeral was the occa- sion of disturbances in the village. This terrible blow, following many smaller miseries, left a very deep mark on Evariste's soul. His hatred of injustice became the more violent, in that he already believed himself to be a victim of it; his father's death incensed him, and developed his tendency to see injustice and baseness everywhere. His repeated failures to be admitted to Polytechnique were to Galois a cause of intense disappointment. To appreciate his de- spair, one must realize that the Ecole Polytechnique was then, not simply the highest mathematical school in France and the place where his genius would be most likely to find the sympathy it craved, it was also a daughter of the Revolution who had remained faithful to her origins in spite of all efforts of the govern- ment to curb her spirit of independence. The young Polytech- nicians were the natural leaders of every political rebellion; lib- eralism was for them a matter of traditional duty. This house was thus twice sacred to Galois, and his failure to be accepted was a double misfortune. In 1 829 he entered the Ecole Normale, but he entered it as an exile from Polytechnique. It was all the more diffi- 90 THE LIFE OF SCIENCE cult for him to forget the object of his former ambition, because the Ecole Normale was then passing through the most languid period of its existence. It was not even an independent institution, but rather an extension of Louis-le-Grand. Every precaution had been taken to ensure the loyalty of this school to the new regime. Yet there, too, the main student body inclined toward liberalism, though their convictions were very weak and passive as com- pared with the mood prevailing at Polytechnique; because of the discipline and the spying methods to which they were submitted, their aspirations had taken a more subdued and hypocritical form only relieved once in a while by spasmodic upheavals. Evariste suffered doubly, for his political desires were checked and his mathematical ability remained unrecognized. Indeed he was easily embarrassed at the blackboard, and made a poor impression upon his teachers. It is quite possible that he did not try in the least to improve this impression. His French biographer, P. Dupuy, very clearly explains his attitude : There was in him a hardly disguised contempt for whosoever did not bow spontaneously and immediately before his superiority, a rebellion against a judgment which his conscience challenged beforehand and a sort of unhealthy pleasure in leading it further astray and in turning it entirely against himself. Indeed, it is fre- quently observed that those people who believe that they have most to complain of persecution could hardly do without it and, if need be, will provoke it. To pass oneself off for a fool is another way and not the least savory, of making fools of others. It is clear that Galois' temper was not altogether amiable, yet we should not judge him without making full allowance for the terrible strain to which he was constantly submitted, the violent conflicts which obscured his soul, the frightful solitude to which fate had condemned him. In the course of the ensuing year, he sent three more papers to mathematical journals and a new memoir to the Academic The permanent secretary, Fourier, took it home with him, but died before having examined it, and the memoir was not retrieved EVARISTE GALOIS 91 from among his papers. Thus his second memoir was lost like the former. This was too much indeed and one will easily forgive the wretched boy if in his feverish mood he was inclined to believe that these repeated losses were not due to chance but to sys- tematic persecution. He considered himself a victim of a bad social organization which ever sacrifices genius to mediocrity, and nat- urally enough he cursed the hated regime of oppression which had precipitated his father's death and against which the storm was gathering. We can well imagine his joy when he heard the first shots of the July Revolution! But alas! While the boys of Polytechnique were the very first in the fray, those of the Ecole Normale were kept under lock and key by their faint-hearted di- rector. It was only when the three glorious days of July were over and the fall of the Bourbons was accomplished that this oppor- tunist let his students out and indeed placed them at the disposal of the provisional government! Never did Galois feel more bitterly that his life had been utterly spoiled by his failure to become an alumnus of his beloved Polytechnique. In the meanwhile the summer holidays began and we do not know what happened to the boy in the interval. It must have been to him a new period of crisis, more acute than any of the previous ones. But before speaking of it let me say a last word about his scientific efforts, for it is probable that thereafter political passion obsessed his mind almost exclusively. At any rate it is certain that Evariste was in the possession of his general principles by the be- ginning of 1830, that is, at the age of eighteen, and that he fully knew their importance. The consciousness of his power and of the responsibility resulting from it increased the concentration and the gloominess of his mind to the danger point; the lack of recognition developed in him an excessive pride. By a strange aberration he did not trouble himself to write his memoirs with sufficient clearness to give the explanations which were the more necessary because his thoughts were more novel. What a pity that there was no understanding friend to whisper in his ear Descartes' wise admonition: "When you have to deal with transcendent 92 THE LIFE OF SCIENCE questions, you must be transcendently clear/' Instead of that, Galois enveloped his thought in additional secrecy by his efforts to attain greater conciseness, that coquetry of mathematicians. It is intensely tragic that this boy already sufficiently harassed by the turmoil of his own thoughts, should have been thrown into the political turmoil of this revolutionary period. Endowed with a stronger constitution, he might have been able to cope with one such; but with the two, how could he — how could anyone do it? During the holidays he was probably pressed by his friend, Chevalier, to join the Saint-Simonists, but he declined, and pre- ferred to join a secret society, less aristocratic and more in keep- ing with his republican aspirations — the "Societe des amis du peuple." It was thus quite another man who re-entered the Ecole Normale in the autumn of 1830. The great events of which he had been a witness had given to his mind a sort of artificial ma- turity. The revolution had opened to him a fresh source of dis- illusion, the deeper because the hopes of the first moment had been so sanguine. The government of Louis-Philippe had promptly crushed the more liberal tendencies; and the artisans of the new revolution, who had drawn their inspiration from the great events of 1789, soon discovered to their intense disgust that they had been fooled. Indeed under a more liberal guise, the same oppres- sion, the same favoritism, the same corruption soon took place under Louis-Philippe as under Charles X. Moreover, nothing can be more demoralizing than a successful revolution (whatever it be) for those who, like Galois, were too generous to seek any personal advantage and too ingenuous not to believe implicitly in their party shibboleths. It is such a high fall from one's dearest ideal to the ugliest aspect of reality — and they could not help seeing around them the more practical and cynical revolutionaries eager for the quarry, and more disgusting still, the clever ones, who had kept quiet until they knew which side was gaining, and who now came out of their hiding places to fight over the spoils and make the most of the new regime. Political fermentation did not abate and the more democratic elements, which Galois had EVARISTE GALOIS 93 joined, became more and more disaffected and restless. The di- rector of the Ecole Normale had been obliged to restrain himself considerably to brook Galois' irregular conduct, his 'laziness/* his intractable temper; the boy's political attitude, and chiefly his undisguised contempt for the director's pusillanimity now in- creased the tension between them to the breaking point. The pub- lication in the "Gazette des Ecoles" of a letter of Galois' in which he scornfully criticized the director's tergiversations was but the last of many offenses. On December 9, he was invited to leave the school, and his expulsion was ratified by the Royal Council on January 3, 1831. To support himself Galois announced that he would give a pri- vate course on higher algebra in the backshop of a bookseller, Mr. Caillot, 5 rue de la Sorbonne. I do not know whether this course, or how much of it, was actually delivered. A further scientific dis- appointment was reserved for him : a new copy of his second lost memoir had been communicated by him to the Academie; it was returned to him by Poisson, four months later, as being incom- prehensible. There is no doubt that Galois was partly responsible for this, for he had taken no pains to explain himself clearly. This was the last straw! Galois' academic career was entirely compromised, the bridges were burned, he plunged himself en- tirely into the political turmoil. He threw himself into it with his habitual fury and the characteristic intransigency of a mathe- matician; there was nothing left to conciliate him, no means to moderate his passion, and he soon reached the extreme limit of exaltation. He is said to have exclaimed : "If a corpse were needed to stir the people up, I would give mine." Thus on May 9, 1831, at the end of a political banquet, being intoxicated — not with wine but with the ardent conversation of an evening — he proposed a sarcastic toast to the King. He held his glass and an open knife in one hand and said simply: "To Louis-Philippe!" Of course he was soon arrested and sent to Ste. Pelagie. The lawyer persuaded him to maintain that he had actually said: "To Louis-Philippe, if he betray/' and many witnesses affirmed that they had heard 94 THE LIFE OF SCIENCE him utter the last words, though they were lost in the uproar. But Galois could not stand this lying and retracted it at the public trial. His attitude before the tribunal was ironical and provoking, yet the jury rendered a verdict of not proven and he was ac- quitted. He did not remain free very long. On the following Four- teenth of July, the government, fearing manifestations, decided to have him arrested as a preventive measure. He was given six months' imprisonment on the technical charge of carrying arms and wearing a military uniform, but he remained in Ste. Pelagie only until March 19 (or 16?), 1832, when he was sent to a con- valescent home in the rue de Lourcine. A dreadful epidemic of cholera was then raging in Paris, and Galois' transfer had been de- termined by the poor state of his health. However, this proved to be his undoing. He was now a prisoner on parole and took advantage of it to carry on an intrigue with a woman of whom we know nothing, but who was probably not very reputable (ffune coquette de bas etage," says Raspail). Think of it! This was, as far as we know, his first love — and it was but one more tragedy on top of so many others. The poor boy who had declared in prison that he could love only a Cornelia or a Tarpeia * (we hear in this an echo of his mother's Roman ideal) , gave himself to this new passion with his usual frenzy, only to find more bitterness at the end of it. His revulsion is lamentably expressed in a letter to Chevalier (May 25, 1832): . . . How to console oneself for having exhausted in one month the greatest source of happiness which is in man — of having ex- hausted it without happiness, without hope, being certain that one has drained it for life? Oh! come and preach peace after that! Come and ask men who suffer to take pity upon what is! Pity, never! Hatred, that is all. He who does not feel it deeply, this hatred of the present, cannot really have in him the love of the future. . . . * He must have quoted Tarpeia by mistake. EVARISTE GALOIS 95 One sees how his particular misery and his political grievances are sadly muddled in his tired head. And a little further in the same letter, in answer to a gentle warning by his friend : I like to doubt your cruel prophecy when you say that I shall not work any more. But I admit it is not without likelihood. To be a savant, I should need to be that alone. 7dy heart has revolted against my head* I do not add as you do: It is a pity. Can a more tragic confession be imagined? One realizes that there is no question here of a man possessing genius, but of genius possessing a man. A man? a mere boy, a fragile little body divided within itself by disproportionate forces, an undeveloped mind crushed mercilessly between the exaltation of scientific discovery and the exaltation of sentiment. Four days later two men challenged him to a duel. The circum- stances of this affair are, and will ever remain, very mysterious. According to Evariste's younger brother the duel was not fair. Evariste, weak as he was, had to deal with two ruffians hired to murder him. I find nothing to countenance this theory except that he was challenged by two men at once. At any rate, it is certain that the woman he had loved played a part in this fateful event. On the day preceding the duel, Evariste wrote three letters of which I translate one : May 29, 1832. Letter to all Republicans. I beg the patriots, my friends, not to reproach me for dying otherwise than for the country. I die the victim of an infamous coquette. My life is quenched in a miserable piece of gossip. Oh ! why do I have to die for such a little thing, to die for some- thing so contemptible! I take heaven to witness that it is only under compulsion that I have yielded to a provocation which I had tried to avert by all means. * The italics arc mine. 96 THE LIFE OF SCIENCE I repent having told a baleful truth to men who were so little able to listen to it coolly. Yet I have told the truth. I take with me to the grave a conscience free from He, free from patriots' blood. Good-bye! I had in me a great deal of life for the public good. Forgiveness for those who killed me; they are of good faith. E. Galois Any comment could but detract from the pathos of this docu- ment. I will only remark that the last line, in which Galois ab- solves his adversaries, destroys his brother's theory. It is simpler to admit that his impetuosity, aggravated by female intrigue, had placed him in an impossible position from which there was no honorable issue, according to the standards of the time, but a duel. Evariste was too much of a gentleman to try to evade the issue, however trifling its causes might be; he was anxious to pay the full price of his folly. That he well realized the tragedy of his life is quite clear from the laconic post-scriptum of his second letter: Aliens lux, horrenda procella, tenebris ceternis involuta. The last letter addressed to his friend, Auguste Chevalier, was a sort of scientific testament. Its seven pages, hastily written, dated at both ends, contain a summary of the discoveries which he had been unable to develop. This statement is so concise and so full that its significance could be understood only gradually as the theories outlined by him were unfolded by others. It proves the depth of his insight, for it anticipates discoveries of a much later date. At the end of the letter, after requesting his friend to pub- lish it and to ask Jacobi or Gauss to pronounce upon it, he added : "After that, I hope some people will find it profitable to unravel this mess. Je t'embrasse avec effusion/' — The first sentence is rather scornful but not untrue and the greatest mathematicians of the century have found it very profitable indeed to clear up Galois' ideas. The duel took place on the 30th in the early morning, and he was grievously wounded by a shot in the abdomen. He was found by a peasant who transported him at 9:30 to the Hopital Cochin. His younger brother — the only member of the family to be noti- EVARISTE GALOIS 97 fied — came and stayed with him, and as he was crying, Evariste tried to console him, saying: "Do not cry. I need all my courage to die at twenty/' While still fully conscious, he refused the as- sistance of a priest. In the evening peritonitis declared itself and he breathed his last at ten o'clock on the following morning. His funeral, which strangely recalled that of his father, was at- tended by two to three thousand republicans, including deputa- tions from various schools, and by a large number of police, for trouble was expected. But everything went off very calmly. Of course it was the patriot and the lover of freedom whom all these people meant to honor; little did they know that a day would come when this young political hero would be hailed as one of the greatest mathematicians of all time. A life as short yet as full as the life of Galois is interesting not simply in itself but even more perhaps because of the light it throws upon the nature of genius. When a great work is the nat- ural culmination of a long existence devoted to one persistent endeavor, it is sometimes difficult to say whether it is the fruit of genius or the fruit of patience. When genius evolves slowly it may be hard to distinguish from talent — but when it explodes suddenly, at the beginning and not at the end of life, or when we are at a loss to explain its intellectual genesis, we can but feel that we are in the sacred presence of something vastly superior to talent. When one is confronted with facts which cannot be ex- plained in the ordinary way, is it not more scientific to admit our ignorance than to hide it behind faked explanations? Of course it is not necessary to introduce any mystical idea, but it is one's duty to acknowledge the mystery. When a work is really the fruit of genius, we cannot conceive that a man of talent might have done it "just as well" by taking the necessary pains. Pains alone will never do; neither is it simply a matter of jumping a little further, for it involves a synthetic process of a higher kind. I do not say that talent and genius are essentially different, but that they are of different orders of magnitude. Galois' fateful existence helps one to understand Lowell's say- 98 THE LIFE OF SCIENCE ing: "Talent is that which is in a man's power, genius is that in whose power man is." If Galois had been simply a mathematician of considerable ability, his life would have been far less tragic, for he could have used his mathematical talent for his own advance- ment and happiness; instead of which, the furor of mathematics — as one of his teachers said — possessed him and he had no al- ternative but absolute surrender to his destiny. Lowell's aphorism is misleading, however, for it suggests that talent can be acquired, while genius cannot. But biological knowl- edge points to the conclusion that neither is really acquired, though both can be developed and to a certain extent corrected by education. Men of talent as well as men of genius are born, not made. Genius implies a much stronger force, less adaptable to environment, less tractable by education, and also far more ex- clusive and despotic. Its very intensity explains its frequent pre- cocity. If the necessary opportunities do not arise, ordinary abilities may remain hidden indefinitely; but the stronger the abili- ties the smaller need the inducement be to awaken them. In the extreme case, the case of genius, the ability is so strong that, if need be, it will force its own outlet. Thus it is that many of the greatest accomplishments of science, art and letters were conceived by very young men. In the field of mathematics, this precocity is particularly obvious. To speak only of the two men considered in this essay, Abel had barely reached the age of twenty-two and Galois was not yet twenty, perhaps not yet nineteen, when they made two of the most profound dis- coveries which have ever been made. In many other sciences and arts, technical apprenticeship may be too long to make such early discovery possible. In most cases, however, the judgment of Alfred de Vigny holds good. "What is a great life? It is a thought of youth wrought out in ripening years." The fundamental concep- tion dawns at an early age — that is, it appears at the surface of one's consciousness as early as this is materially possible — but it is often so great that a long life of toil and abnegation is but too short to work it out. Of course at the beginning it may be very EVARISTE GALOIS 99 vague, so vague indeed that its host can hardly distinguish it him- self from a passing fancy, and later may be unable to explain how it gradually took control of his activities and dominated his whole being. The cases of Abel and Galois are not essentially different from those contemplated by Alfred de Vigny, but the golden thoughts of their youth were wrought out in the ripening years of other people. It is the precocity of genius which makes it so dramatic. When it takes an explosive form, as in the case of Galois, the frail carcass of a boy may be unable to resist the internal strain and it may be positively wrecked. On the other hand when genius develops more slowly, its host has time to mature, to adapt himself to his environment, to gather strength and experience. He learns to reconcile himself to the conditions which surround him, widely different as they are, from those of his dreams. He learns by and by that the great majority of men are rather unintelligent, unedu- cated, uninspired, and that one must not take it too much to heart when they behave in defiance of justice or even of common sense. He also learns to dissipate his vexation with a smile or a joke and to protect himself under a heavy cloak of kindness and humor. Poor Evariste had no time to learn all this. While his genius grew in him out of all proportion to his bodily strength, his experience and his wisdom, he felt more and more ill at ease. His increasing restlessness makes one think of that exhibited by people who are prey to a larvate form of a pernicious disease. There is an internal disharmony in both cases, though it is physiological in the latter, and psychological in the former. Hence the suffering, the distress and finally the acute disease or the revolt! A more congenial environment might have saved Galois. Oh! would that he had been granted that minimum of understanding and sympathy which the most concentrated mind needs as much as a plant needs the sun! . . . But it was not to be; and not only had he no one to share his own burden, but he had also to bear the anxieties of a stormy time. I quite realize that this self-centered boy was not attractive — many would say not lovable. Yet I love 100 THE LIFE OF SCIENCE him; I love him for all those who failed to love him; I love him be- cause of his adversity. His tragic life teaches us at least one great lesson : one can never be too kind to the young; one can never be too tolerant of their faults, even of their intolerance. The pride and intolerance of youth, however immoderate, are excusable because of youth's ignorance, and also because one may hope that it is only a tempo- rary disorder. Of course there will always be men despicable enough to resort to snubbing, as it were, to protect their own posi- tion and to hide their mediocrity, but I am not thinking of them. I am simply thinking of the many men who were unkind to Galois without meaning to be so. To be sure, one could hardly expect them to divine the presence of genius in an awkward boy. But even if they did not believe in him, could they not have shown more forbearance? Even if he had been a conceited dunce, instead of a genius, could kindness have harmed him? ... It is painful to think that a few rays of generosity from the heart of his elders might have saved this boy or at least might have sweetened his life. But does it really matter? A few years more or less, a little more or less suffering. . . . Life is such a short drive altogether. Galois has accomplished his task and very few men will ever accomplish more. He has conquered the purest kind of immortality. As he wrote to his friends: