Albert Einstein. The world as I see it PREFACE TO ORIGINAL EDITION Only individuals have a sense of responsibility. --Nietzsche This book does not represent a complete collection of the articles, addresses, and pronouncements of Albert Einstein; it is a selection made with a definite object-- namely, to give a picture of a man. To-day this man is being drawn, contrary to his own intention, into the whirlpool of political passions and contemporary history. As a result, Einstein is experiencing the fate that so many of the great men of history experienced: his character and opinions are being exhibited to the world in an utterly distorted form. To forestall this fate is the real object of this book. It meets a wish that has constantly been expressed both by Einstein's friends and by the wider public. It contains work belonging to the most various dates-- the article on "The International of Science" dates from the year 1922, the address on "The Principles of Scientific Research" from 1923, the "Letter to an Arab" from 1930--and the most various spheres, held together by the unity of the personality which stands behind all these utterances. Albert Einstein believes in humanity, in a peaceful world of mutual helpfulness, and in the high mission of science. This book is intended as a plea for this belief at a time which compels every one of us to overhaul his mental attitude and his ideas. J. H. INTRODUCTION TO ABRIDGED EDITION In his biography of Einstein Mr. H. Gordou Garbedian relates that an American newspaper man asked the great physicist for a definition of his theory of relativity in one sentence. Einstein replied that it would take him three days to give a short definition of relativity. He might well have added that unless his questioner had an intimate acquaintance with mathematics and physics, the definition would be incomprehensible. To the majority of people Einstein's theory is a complete mystery. Their attitude towards Einstein is like that of Mark Twain towards the writer of a work on mathematics: here was a man who had written an entire book of which Mark could not understand a single sentence. Einstein, therefore, is great in the public eye partly because he has made revolutionary discoveries which cannot be translated into the common tongue. We stand in proper awe of a man whose thoughts move on heights far beyond our range, whose achievements can be measured only by the few who are able to follow his reasoning and challenge his conclusions. There is, however, another side to his personality. It is revealed in the addresses, letters, and occasional writings brought together in this book. These fragments form a mosaic portrait of Einstein the man. Each one is, in a sense, complete in itself; it presents his views on some aspect of progress, education, peace, war, liberty, or other problems of universal interest. Their combined effect is to demonstrate that the Einstein we can all understand is no less great than the Einstein we take on trust. Einstein has asked nothing more from life than the freedom to pursue his researches into the mechanism of the universe. His nature is of rare simplicity and sincerity; he always has been, and he remains, genuinely indifferent to wealth and fame and the other prizes so dear to ambition. At the same time he is no recluse, shutting himself off from the sorrows and agitations of the world around him. Himself familiar from early years with the handicap of poverty and with some of the worst forms of man's inhumanity to man, he has never spared himself in defence of the weak and the oppressed. Nothing could be more unwelcome to his sensitive and retiring character than the glare of the platform and the heat of public controversy, yet he has never hesitated when he felt that his voice or influence would help to redress a wrong. History, surely, has few parallels with this introspective mathematical genius who laboured unceasingly as an eager champion of the rights of man. Albert Einstein was born in 1879 at Ulm. When he was four years old his father, who owned an electrochemical works, moved to Munich, and two years later the boy went to school, experiencing a rigid, almost military, type of discipline and also the isolation of a shy and contemplative Jewish child among Roman Catholics-- factors which made a deep and enduring impression. From the point of view of his teachers he was an unsatisfactory pupil, apparently incapable of progress in languages, history, geography, and other primary subjects. His interest in mathematics was roused, not by his instructors, but by a Jewish medical student, Max Talmey, who gave him a book on geometry, and so set him upon a course of enthusiastic study which made him, at the age of fourteen, a better mathematician than his masters. At this stage also he began the study of philosophy, reading and re-reading the words of Kant and other metaphysicians. Business reverses led the elder Einstein to make a fresh start in Milan, thus introducing Albert to the joys of a freer, sunnier life than had been possible in Germany. Necessity, however, made this holiday a brief one, and after a few months of freedom the preparation for a career began. It opened with an effort, backed by a certificate of mathematical proficiency given by a teacher in the Gymnasium at Munich, to obtain admission to the Polytechnic Academy at Zurich. A year passed in the study of necessary subjects which he had neglected for mathematics, but once admitted, the young Einstein became absorbed in the pursuit of science and philosophy and made astonishing progress. After five distinguished years at the Polytechnic he hoped to step into the post of assistant professor, but found that the kindly words of the professors who had stimulated the hope did not materialize. Then followed a weary search for work, two brief interludes of teaching, and a stable appointment as examiner at the Confederate Patent Office at Berrie. Humdrum as the work was, it had the double advantage of providing a competence and of leaving his mind free for the mathematical speculations which were then taking shape in the theory of relativity. In 1905 his first monograph on the theory was published in a Swiss scientific journal, the Annalen der Physik. Zurich awoke to the fact that it possessed a genius in the form of a patent office clerk, promoted him to be a lecturer at the University and four years later--in 1909--installed him as Professor. His next appointment was (in 1911) at the University of Prague, where he remained for eighteen months. Following a brief return to Zurich, he went, early in 1914, to Berlin as a professor in the Prussian Academy of Sciences and director of the Kaiser Wilhelm Institute for Theoretical Physics. The period of the Great War was a trying time for Einstein, who could not conceal his ardent pacifism, but he found what solace he could in his studies. Later events brought him into the open and into many parts of the world, as an exponent not only of pacifism but also of world-disarmament and the cause of Jewry. To a man of such views, as passionately held as they were by Einstein, Germany under the Nazis was patently impossible. In 1933 Einstein made his famous declaration: "As long as I have any choice, I will stay only in a country where political liberty, toleration, and equality of all citizens before the law are the rule." For a time he was a homeless exile; after offers had come to him from Spain and France and Britain, he settled in Princeton as Professor of Mathematical and Theoretical Physics, happy in his work, rejoicing in a free environment, but haunted always by the tragedy of war and oppression. The World As I See It, in its original form, includes essays by Einstein on relativity and cognate subjects. For reasons indicated above, these have been omitted in the present edition; the object of this reprint is simply to reveal to the general reader the human side of one of the most dominating figures of our day. I The World As I See It The Meaning of Life What is the meaning of human life, or of organic life altogether? To answer this question at all implies a religion. Is there any sense then, you ask, in putting it? I answer, the man who regards his own life and that of his fellow-creatures as meaningless is not merely unfortunate but almost disqualified for life. The World as I see it What an extraordinary situation is that of us mortals! Each of us is here for a brief sojourn; for what purpose he knows not, though he sometimes thinks he feels it. But from the point of view of daily life, without going deeper, we exist for our fellow-men--in the first place for those on whose smiles and welfare all our happiness depends, and next for all those unknown to us personally with whose destinies we are bound up by the tie of sympathy. A hundred times every day I remind myself that my inner and outer life depend on the labours of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am still receiving. I am strongly drawn to the simple life and am often oppressed by the feeling that I am engrossing an unnecessary amount of the labour of my fellow-men. I regard class differences as contrary to justice and, in the last resort, based on force. I also consider that plain living is good for everybody, physically and mentally. In human freedom in the philosophical sense I am definitely a disbeliever. Everybody acts not only under external compulsion but also in accordance with inner necessity. Schopenhauer's saying, that "a man can do as he will, but not will as he will," has been an inspiration to me since my youth up, and a continual consolation and unfailing well-spring of patience in the face of the hardships of life, my own and others'. This feeling mercifully mitigates the sense of responsibility which so easily becomes paralysing, and it prevents us from taking ourselves and other people too seriously; it conduces to a view of life in which humour, above all, has its due place. To inquire after the meaning or object of one's own existence or of creation generally has always seemed to me absurd from an objective point of view. And yet everybody has certain ideals which determine the direction of his endeavours and his judgments. In this sense I have never looked upon ease and happiness as ends in themselves--such an ethical basis I call more proper for a herd of swine. The ideals which have lighted me on my way and time after time given me new courage to face life cheerfully, have been Truth, Goodness, and Beauty. Without the sense of fellowship with men of like mind, of preoccupation with the objective, the eternally unattainable in the field of art and scientific research, life would have seemed to me empty. The ordinary objects of human endeavour--property, outward success, luxury--have always seemed to me contemptible. My passionate sense of social justice and social responsibility has always contrasted oddly with my pronounced freedom from the need for direct contact with other human beings and human communities. I gang my own gait and have never belonged to my country, my home, my friends, or even my immediate family, with my whole heart; in the face of all these ties I have never lost an obstinate sense of detachment, of the need for solitude--a feeling which increases with the years. One is sharply conscious, yet without regret, of the limits to the possibility of mutual understanding and sympathy with one's fellow-creatures. Such a person no doubt loses something in the way of geniality and light-heartedness ; on the other hand, he is largely independent of the opinions, habits, and judgments of his fellows and avoids the temptation to take his stand on such insecure foundations. My political ideal is that of democracy. Let every man be respected as an individual and no man idolized. It is an irony of fate that I myself have been the recipient of excessive admiration and respect from my fellows through no fault, and no merit, of my own. The cause of this may well be the desire, unattainable for many, to understand the one or two ideas to which I have with my feeble powers attained through ceaseless struggle. I am quite aware that it is necessary for the success of any complex undertaking that one man should do the thinking and directing and in general bear the responsibility. But the led must not be compelled, they must be able to choose their leader. An autocratic system of coercion, in my opinion, soon degenerates. For force always attracts men of low morality, and I believe it to be an invariable rule that tyrants of genius are succeeded by scoundrels. For this reason I have always been passionately opposed to systems such as we see in Italy and Russia to-day. The thing that has brought discredit upon the prevailing form of democracy in Europe to-day is not to be laid to the door of the democratic idea as such, but to lack of stability on the part of the heads of governments and to the impersonal character of the electoral system. I believe that in this respect the United States of America have found the right way. They have a responsible President who is elected for a sufficiently long period and has sufficient powers to be really responsible. On the other hand, what I value in our political system is the more extensive provision that it makes for the individual in case of illness or need. The really valuable thing in the pageant of human life seems to me not the State but the creative, sentient individual, the personality; it alone creates the noble and the sublime, while the herd as such remains dull in thought and dull in feeling. This topic brings me to that worst outcrop of the herd nature, the military system, which I abhor. That a man can take pleasure in marching in formation to the strains of a band is enough to make me despise him. He has only been given his big brain by mistake; a backbone was all he needed. This plague-spot of civilization ought to be abolished with all possible speed. Heroism by order, senseless violence, and all the pestilent nonsense that does by the name of patriotism--how I hate them! War seems to me a mean, contemptible thing: I would rather be hacked in pieces than take part in such an abominable business. And yet so high, in spite of everything, is my opinion of the human race that I believe this bogey would have disappeared long ago, had the sound sense of the nations not been systematically corrupted by commercial and political interests acting through the schools and the Press. The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. He who knows it not and can no longer wonder, no longer feel amazement, is as good as dead, a snuffed-out candle. It was the experience of mystery--even if mixed with fear--that engendered religion. A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms--it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man. I cannot conceive of a God who rewards and punishes his creatures, or has a will of the type of which we are conscious in ourselves. An individual who should survive his physical death is also beyond my comprehension, nor do I wish it otherwise; such notions are for the fears or absurd egoism of feeble souls. Enough for me the mystery of the eternity of life, and the inkling of the marvellous structure of reality, together with the single-hearted endeavour to comprehend a portion, be it never so tiny, of the reason that manifests itself in nature. The Liberty of Doctrine--Î propos of the Guntbel Case Academic chairs are many, but wise and noble teachers are few; lecture-rooms are numerous and large, but the number of young people who genuinely thirst after truth and justice is small. Nature scatters her common wares with a lavish hand, but the choice sort she produces but seldom. We all know that, so why complain? Was it not ever thus and will it not ever thus remain? Certainly, and one must take what Nature gives as one finds it. But there is also such a thing as a spirit of the times, an attitude of mind characteristic of a particular generation, which is passed on from individual to individual and gives a society its particular tone. Each of us has to do his little bit towards transforming this spirit of the times. Compare the spirit which animated the youth in our universities a hundred years ago with that prevailing to-day. They had faith in the amelioration of human society, respect for every honest opinion, the tolerance for which our classics had lived and fought. In those days men strove for a larger political unity, which at that time was called Germany. It was the students and the teachers at the universities who kept these ideals alive. To-day also there is an urge towards social progress, towards tolerance and freedom of thought, towards a larger political unity, which we to-day call Europe. But the students at our universities have ceased as completely as their teachers to enshrine the hopes and ideals of the nation. Anyone who looks at our times coolly and dispassionately must admit this. We are assembled to-day to take stock of ourselves. The external reason for this meeting is the Gumbel case. This apostle of justice has written about unexpiated political crimes with devoted industry, high courage, and exemplary fairness, and has done the community a signal service by his books. And this is the man whom the students, and a good many of the staff, of his university are to-day doing their best to expel. Political passion cannot be allowed to go to such lengths. I am convinced that every man who reads Herr Gumbel's books with an open mind will get the same impression from them as I have. Men like him are needed if we are ever to build up a healthy political society. Let every man judge according to his own standards, by what he has himself read, not by what others tell him. If that happens, this Gumbel case, after an unedifying beginning, may still do good. Good and Evil It is right in principle that those should be the best loved who have contributed most to the elevation of the human race and human life. But, if one goes on to ask who they are, one finds oneself in no inconsiderable difficulties. In the case of political, and even of religious, leaders, it is often very doubtful whether they have done more good or harm. Hence I most seriously believe that one does people the best service by giving them some elevating work to do and thus indirectly elevating them. This applies most of all to the great artist, but also in a lesser degree to the scientist. To be sure, it is not the fruits of scientific research that elevate a man and enrich his nature, but the urge to understand, the intellectual work, creative or receptive. It would surely be absurd to judge the value of the Talmud, for instance, by its intellectual fruits. The true value of a human being is determined primarily by the measure and the sense in which he has attained to liberation from the self. Society and Personality When we survey our lives and endeavours we soon observe that almost the whole of our actions and desires are bound up with the existence of other human beings. We see that our whole nature resembles that of the social animals. We eat food that others have grow, wear clothes that others have made, live in houses that others have built. The greater part of our knowledge and beliefs has been communicated to us by other people through the medium of a language which others have created. Without language our mental capacities wuuld be poor indeed, comparable to those of the higher animals; we have, therefore, to admit that we owe our principal advantage over the beasts to the fact of living in human society. The individual, if left alone from birth would remain primitive and beast-like in his thoughts and feelings to a degree that we can hardly conceive. The individual is what he is and has the significance that he has not so much in virtue of his individuality, but rather as a member of a great human society, which directs his material and spiritual existence from the cradle to the grave. A man's value to the community depends primarily on how far his feelings, thoughts, and actions are directed towards promoting the good of his fellows. We call him good or bad according to how he stands in this matter. It looks at first sight as if our estimate of a man depended entirely on his social qualities. And yet such an attitude would be wrong. It is clear that all the valuable things, material, spiritual, and moral, which we receive from society can be traced back through countless generations to certain creative individuals. The use of fire, the cultivation of edible plants, the steam engine--each was discovered by one man. Only the individual can think, and thereby create new values for society--nay, even set up new moral standards to which the life of the community conforms. Without creative, independently thinking and judging personalities the upward development of society is as unthinkable as the development of the individual personality without the nourishing soil of the community. The health of society thus depends quite as much on the independence of the individuals composing it as on their close political cohesion. It has been said very justly that GrÄco-Europeo-American culture as a whole, and in particular its brilliant flowering in the Italian Renaissance, which put an end to the stagnation of mediÄval Europe, is based on the liberation and comparative isolation of the individual. Let us now consider the times in which we live. How does society fare, how the individual? The population of the civilized countries is extremely dense as compared with former times; Europe to-day contains about three times as many people as it did a hundred years ago. But the number of great men has decreased out of all proportion. Only a few individuals are known to the masses as personalities, through their creative achievements. Organization has to some extent taken the place of the great man, particularly in the technical sphere, but also to a very perceptible extent in the scientific. The lack of outstanding figures is particularly striking in the domain of art. Painting and music have definitely degenerated and largely lost their popular appeal. In politics not only are leaders lacking, but the independence of spent and the sense of justice of the citizen have to a great extent declined. The democratic, parliamentarian regime, which is based on such independence, has in many places been shaken, dictatorships have sprung up and are tolerated, because men's sense of the dignity and the rights of the individual is no longer strong enough. In two weeks the sheep-like masses can be worked up by the newspapers into such a state of excited fury that the men are prepared to put on uniform and kill and be billed, for the sake of the worthless aims of a few interested parties. Compulsory military service seems to me the most disgraceful symptom of that deficiency in personal dignity from which civilized mankind is suffering to-day. No wonder there is no lack of prophets who prophesy the early eclipse of our civilization. I am not one of these pessimists; I believe that better times are coming. Let me shortly state my reasons for such confidence. In my opinion, the present symptoms of decadence are explained by the fact that the development of industry and machinery has made the struggle for existence very much more severe, greatly to the detriment of the free development of the individual. But the development of machinery means that less and less work is needed from the individual for the satisfaction of the community's needs. A planned division of labour is becoming more and more of a crying necessity, and this division will lead to the material security of the individual. This security and the spare time and energy which the individual will have at his command can be made to further his development. In this way the community may regain its health, and we will hope that future historians will explain the morbid symptoms of present-day society as the childhood ailments of an aspiring humanity, due entirely to the excessive speed at which civilization was advancing. Address at the Grave of H. A. Lorentz It is as the representative of the German-speaking academic world, and in particular the Prussian Academy of Sciences, but above all as a pupil and affectionate admirer that I stand at the grave of the greatest and noblest man of our times. His genius was the torch which lighted the way from the teachings of Clerk Maxwell to the achievements of contemporary physics, to the fabric of which he contributed valuable materials and methods. His life was ordered like a work of art down to the smallest detail. His never-failing kindness and magnanimity and his sense of justice, coupled with an intuitive understanding of people and things, made him a leader in any sphere he entered. Everyone followed him gladly, for they felt that he never set out to dominate but always simply to be of use. His work and his example will live on as an inspiration and guide to future generations. H. A. Lorentz's work in the cause of International Co-operation With the extensive specialization of scientific research which the nineteenth century brought about, it has become rare for a man occupying a leading position in one of the sciences to manage at the same time to do valuable service to the community in the sphere of international organization and international. politics. Such service demands not only energy, insight, and a reputation based on solid achievements, but also a freedom from national prejudice and a devotion to the common ends of all, which have become rare in our times. I have met no one who combined all these qualities in himself so perfectly as H. A. Lorentz. The marvellous thing about the effect of his personality was this: Independent and headstrong natures, such as are particularly common among men of learning, do not readily bow to another's will and for the most part only accept his leadership grudgingly. But, when Lorentz is in the presidential chair, an atmosphere of happy co-operation is invariably created, however much those present may differ in their aims and habits of thought. The secret of this success lies not only in his swift comprehension of people and things and his marvellous command of language, but above all in this, that one feels that his whole heart is in the business in hand, and that, when he is at work, he has room for nothing else in his mind. Nothing disarms the recalcitrant so much as this. Before the war Lorentz's activities in the cause of international relations were confined to presiding at congresses of physicists. Particularly noteworthy among these were the Solvay Congresses, the first two of which were held at Brussels in 1909 and 1912. Then came the European war, which was a crushing blow to all who had the improvement of human relations in general at heart. Even before the war was over, and still more after its end, Lorentz devoted himself to the work of reconciliation. His efforts were especially directed towards the re-establishment of fruitful and friendly co-operation between men of learning and scientific societies. An outsider can hardly conceive what uphill work this is. The accumulated resentment of the war period has not yet died down, and many influential men persist in the irreconcilable attitude into which they allowed themselves to be driven by the pressure of circumstances. Hence Lorentz's efforts resemble those of a doctor with a recalcitrant patient who refuses to take the medicines carefully prepared for his benefit. But Lorentz is not to be deterred, once he has recognized a course of action as the right one. The moment the war was over, he joined the governing body of the "Conseil de recherche," which was founded by the savants of the victorious countries, and from which the savants and learned societies of the Central Powers were excluded. His object in taking this step, which caused great offence to the academic world of the Central Powers, was to influence this institution in such a way that it could be expanded into something truly international. He and other right-minded men succeeded, after repeated efforts, in securing the removal of the offensive exclusion-clause from the statutes of the "Conseil." The goal, which is the restoration of normal and fruitful co-operation between learned societies, is, however, not yet attained, because the academic world of the Central Powers, exasperated by nearly ten years of exclusion from practically all international gatherings, has got into a habit of keeping itself to itself. Now, however, there are good grounds for hoping that the ice will soon be broken, thanks to the tactful efforts of Lorentz, prompted by pure enthusiasm for the good cause. Lorentz has also devoted his energies to the service of international cultural ends in another way, by consenting to serve on the League of Nations Commission for international intellectual co-operation, which was called into existence some five years ago with Bergson as chairman. For the last year Lorentz has presided over the Commission, which, with the active support of its subordinate, the Paris Institute, is to act as a go-between in the domain of intellectual and artistic work among the various spheres of culture. There too the beneficent influence of this intelligent, humane, and modest personality, whose unspoken but faithfully followed advice is, "Not mastery but service," will lead people in the right way. May his example contribute to the triumph of that spirit ! In Honour of Arnold Berliner's Seventieth Birthday (Arnold Berliner is the editor of the periodical Die Naturrvissenschaften.) I should like to take this opportunity of telling my friend Berliner and the readers of this paper why I rate him and his work so highly. It has to be done here because it is one's only chance of getting such things said; since our training in objectivity has led to a taboo on everything personal, which we mortals may transgress only on quite exceptional occasions such as the present one. And now, after this dash for liberty, back to the objective! The province of scientifically determined fact has been enormously extended, theoretical knowledge has become vastly more profound in every department of science. But the assimilative power of the human intellect is and remains strictly limited. Hence it was inevitable that the activity of the individual investigator should be confined to a smaller and smaller section of human knowledge. Worse still, as a result of this specialization, it is becoming increasingly difficult for even a rough general grasp of science as a whole, without which the true spirit of research is inevitably handicapped, to keep pace with progress. A situation is developing similar to the one symbolically represented in the Bible by the story of the Tower of Babel. Every serious scientific worker is painfully conscious of this involuntary relegation to an ever-narrowing sphere of knowledge, which is threatening to deprive the investigator of his broad horizon and degrade him to the level of a mechanic. We have all suffered under this evil, without making any effort to mitigate it. But Berliner has come to the rescue, as far as the German-speaking world is concerned, in the most admirable way: He saw that the existing popular periodicals were sufficient to instruct and stimulate the layman; but he also saw that a first-class, well-edited organ was needed for the guidance of the scientific worker who desired to be put sufficiently au courant of developments in scientific problems, methods, and results to be able to form a judgment of his own. Through many years of hard work he has devoted himself to this object with great intelligence and no less great determination, and done us all, and science, a service for which we cannot be too grateful. It was necessary for him to secure the co-operation of successful scientific writers and induce them to say what they had to say in a form as far as possible intelligible to non-specialists. He has often told me of the fights he had in pursuing this object, the difficulties of which he once described to me in the following riddle: Question : What is a scientific author? Answer: A cross between a mimosa and a porcupine.* Berliner's achievement would have been impossible but for the peculiar intensity of his longing for a clear, comprehensive view of the largest possible area of scientific country. This feeling also drove him to produce a text-book of physics, the fruit of many years of strenuous work, of which a medical student said to me the other day: "I don't know how I should ever have got a clear idea of the principles of modern physics in the time at my disposal without this book." Berliner's fight for clarity and comprehensiveness of outlook has done a great deal to bring the problems, methods, and results of science home to many people's minds. The scientific life of our time is simply inconceivable vzthout his paper. It is just as important to make knowledge live and to keep it alive as to solve specific problems. We are all conscious of what we owe to Arnold Berliner. *Do not be angry with me for this indiscretion, my dear Berliner. A serious-minded man enjoys a good laugh now and then. Popper-Lynhaus was more than a brilliant engineer and writer. He was one of the few outstanding personalities who embody the conscience of a generation. He has drummed it into us that society is responsible for the fate of every individual and shown us a way to translate the consequent obligation of the community into fact. The community or State was no fetish to him; he based its right to demand sacrifices of the individual entirely on its duty to give the individual personality a chance of harmonious development. Obituary of the Surgeon, M. Katzenstein During the eighteen years I spent in Berlin I had few close friends, and the closest was Professor Katzenstein. For more than ten years I spent my leisure hours during the summer months with him, mostly on his delightful yacht. There we confided our experiences, ambitions, emotions to each other. We both felt that this friendship was not only a blessing because each understood the other, was enriched by him, and found ins him that responsive echo so essential to anybody who is truly alive; it also helped to make both of us more independent of external experience, to objectivize it more easily. I was a free man, bound neither by many duties nor by harassing responsibilities; my friend, on the contrary, was never free from the grip of urgent duties and anxious fears for the fate of those in peril. If, as was invariably the case, he had performed some dangerous operations in the morning, he would ring up on the telephone, immediately before we got into the boat, to enquire after the condition of the patients about whom he was worried; I could see how deeply concerned he was for the lives entrusted to his care. It was marvellous that this shackled outward existence did not clip the wings of his soul; his imagination and his sense of humour were irrepressible. He never became the typical conscientious North German, whom the Italians in the days of their freedom used to call bestia seriosa. He was sensitive as a youth to the tonic beauty of the lakes and woods of Brandenburg, and as he sailed the boat with an expert hand through these beloved and familiar surroundings he opened the secret treasure-chamber of his heart to me--he spoke of his experiments, scientific ideas, and ambitions. How he found time and energy for them was always a mystery to me; but the passion for scientific enquiry is not to be crushed by any burdens. The man who is possessed with it perishes sooner than it does. There were two types of problems that engaged his attention. The first forced itself on him out of the necessities of his practice. Thus he was always thinking out new ways of inducing healthy muscles to take the place of lost ones, by ingenious transplantation of tendons. He found this remarkably easy, as he possessed an uncommonly strong spatial imagination and a remarkably sure feeling for mechanism. How happy he was when he had succeeded in making somebody fit for normal life by putting right the muscular system of his face, foot, or arm! And the same when he avoided an operation, even in cases which had been sent to him by physicians for surgical treatment in cases of gastric ulcer by neutralizing the pepsin. He also set great store by the treatment of peritonitis by an anti-toxic coli-serum which he discovered, and rejoiced in the successes he achieved with it. In talking of it he often lamented the fact that this method of treatment was not endorsed by his colleagues. The second group of problems had to do with the common conception of an antagonism between different sorts of tissue. He believed that he was here on the track of a general biological principle of widest application, whose implications he followed out with admirable boldness and persistence. Starting out from this basic notion he discovered that osteomyelon and periosteum prevent each other's growth if they are not separated from each other by bone. In this way he succeeded in explaining hitherto inexplicable cases of wounds ailing to heal, and in bringing about a cure. This general notion of the antagonism of the tissues, especially of epithelium and connective tissue, was the subject to which he devoted his scientific energies, especially in the last ten years of his life. Experiments on animals and a systematic investigation of the growth of tissues in a nutrient fluid were carried out side by side. How thankful he was, with his hands tied as they were by his duties, to have found such an admirable and infinitely enthusiastic fellow-worker in Fr´lein Knake! He succeeded in securing wonderful results bearing on the factors which favour the growth of epithelium at the expense of that of connective tissue, results which may well be of decisive importance for the study of cancer. He also had the pleasure of inspiring his own son to become his intelligent and independent fellow-worker, and of exciting the warm interest and co-operation of Sauerbruch just in the last years of his life, so that he was able to die with the consoling thought that his life's work would not perish, but