As a child, I received instruction both in the Bible and in the Talmud. I am a Jew, but I am enthralled by the luminous figure of the Nazarene.

I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.

I believe in intuitions and inspirations. I sometimes feel that I am right. I do not know that I am. When two expeditions of scientists, financed by the Royal Academy, went forth to test my theory of relativity, I was convinced that their conclusions would tally with my hypothesis. I was not surprised when the eclipse of May 29, 1919, confirmed my intuitions. I would have been surprised if I had been wrong.

The only progress I can see is progress in the organization. The ordinary human being does not live long enough to draw any substantial benefit from his own experience. And no one, it seems, can benefit by the experiences of others. Being both a father and teacher, I know we can teach our children nothing. We can transmit to them neither our knowledge of life nor of mathematics. Each must learn its lesson anew.

But to return to the Jewish question. Other groups and nations cultivate their individual traditions. There is no reason why we should sacrifice ours. Standardization robs life of its spice. To deprive every ethnic group of its special traditions is to convert the world into a huge Ford plant. I believe in standardizing automobiles. I do not believe in standardizing human beings. Standardization is a great peril which threatens American culture.

Why does this magnificent applied science which saves work and makes life easier bring us so little happiness? The simple answer runs: Because we have not yet learned to make sensible use of it. In war it serves that we may poison and mutilate each other. In peace it has made our lives hurried and uncertain. Instead of freeing us in great measure from spiritually exhausting labor, it has made men into slaves of machinery, who for the most part complete their monotonous long day's work with disgust and must continually tremble for their poor rations. ... It is not enough that you should understand about applied science in order that your work may increase man's blessings. Concern for the man himself and his fate must always form the chief interest of all technical endeavours; concern for the great unsolved problems of the organization of labor and the distribution of goods in order that the creations of our mind shall be a blessing and not a curse to mankind. Never forget this in the midst of your diagrams and equations.

Everyone sits in the prison of his own ideas; he must burst it open, and that in his youth, and so try to test his ideas on reality.

I have only two rules which I regard as principles of conduct. The first is: Have no rules. The second is: Be independent of the opinion of others.

I do not believe in a God who maliciously or arbitrarily interferes in the personal affairs of mankind. My religion consists of a humble admiration for the vast power which manifests itself in that small part of the universe which our poor, weak minds can grasp!

Much reading after a certain age diverts the mind from its creative pursuits. Any man who reads too much and uses his own brain too little falls into lazy habits of thinking, just as the man who spends too much time in the theaters is apt to be content with living vicariously instead of living his own life.

Every man knows that in his work he does best and accomplishes most when he has attained a proficiency that enables him to work intuitively. That is, there are things which we come to know so well that we do not know how we know them. So it seems to me in matters of principle. Perhaps we live best and do things best when we are not too conscious of how and why we do them.

The moral decline we are compelled to witness and the suffering it engenders are so oppressive that one cannot ignore them even for a moment. No matter how deeply one immerses oneself in work, a haunting feeling of inescapable tragedy persists. Still, there are moments when one feels free from one's own identification with human limitations and inadequacies. At such moments, one imagines that one stands on some spot of a small planet, gazing in amazement at the cold yet profoundly moving beauty of the eternal, the unfathomable: life and death flow into one, and there is neither evolution nor destiny; only being.

Fundamental ideas play the most essential role in forming a physical theory. Books on physics are full of complicated mathematical formulae. But thought and ideas, not formulae, are the beginning of every physical theory. The ideas must later take the mathematical form of a quantitative theory, to make possible the comparison with experiment.

Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all the things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility or the meaning of such a comparison. But he certainly believes that, as his knowledge increases, his picture of reality will become simpler and simpler and will explain a wider and wider range of his sensuous impressions. He may also believe in the existence of the ideal limit of knowledge and that it is approached by the human mind. He may call this ideal limit the objective truth.

Everyone who is seriously involved in the pursuit of science becomes convinced that some spirit is manifest in the laws of the universe, one that is vastly superior to that of man.

It has often been said, and certainly not without justification, that the man of science is a poor philosopher. Why then should it not be the right thing for the physicist to let the philosopher do the philosophizing? Such might indeed be the right thing to do at a time when the physicist believes he has at his disposal a rigid system of fundamental laws which are so well established that waves of doubt can't reach them; but it cannot be right at a time when the very foundations of physics itself have become problematic as they are now. At a time like the present, when experience forces us to seek a newer and more solid foundation, the physicist cannot simply surrender to the philosopher the critical contemplation of theoretical foundations; for he himself knows best and feels more surely where the shoe pinches. In looking for an new foundation, he must try to make clear in his own mind just how far the concepts which he uses are justified, and are necessities.

The whole of science is nothing more than a refinement of every day thinking.

Without disarmament there can be no lasting peace. On the contrary, the continuation of military armaments in their present extent will with certainty lead to new catastrophies...For the creation of this public opinion in favor of disarmament every person living shares the responsibility, through ever deed and every word.

What the inventive genius of mankind has bestowed upon us in the last hundred years could have made human life care free and happy if the development of the organizing power of man had been able to keep step with his technical advances. As it is, the hardly bought achievements of the machine age in the hands of our generation are as dangerous as a razor in the hands of a three-year-old child. The possession of wonderful means of production has not brought freedom-only care and hunger.

As an eminent pioneer in the realm of high frequency currents... I congratulate you on the great successes of your life's work.

I see a clock, but I cannot envision the clockmaker. The human mind is unable to conceive of the four dimensions, so how can it conceive of a God, before whom a thousand years and a thousand dimensions are as one?

No man can visualize four dimensions, except mathematically ... I think in four dimensions, but only abstractly. The human mind can picture these dimensions no more than it can envisage electricity. Nevertheless, they are no less real than electro-magnetism, the force which controls our universe, within, and by which we have our being.

We may assume the existence of an aether; only we must give up ascribing a definite state of motion to it, i.e. we must by abstraction take from it the last mechanical characteristic which Lorentz had still left it. ... But this ether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it.

I have come to believe that the motion of the Earth cannot be detected by any optical experiment.

May they not forget to keep pure the great heritage that puts them ahead of the West: the artistic configuration of life, the simplicity and modesty of personal needs, and the purity and serenity of the Japanese soul.

Whether you can observe a thing or not depends on the theory which you use. It is the theory which decides what can be observed.

But what can be the attraction of getting to know such a tiny section of nature thoroughly, while one leaves everything subtler and more complex shyly and timidly alone? Does the product of such a modest effort deserve to be called by the proud name of a theory of the universe? In my belief the name is justified; for the general laws on which the structure of theoretical physics is based claim to be valid for any natural phenomenon whatsoever. With them, it ought to be possible to arrive at the description, that is to say, the theory, of every natural process, including life, by means of pure deduction, if that process of deduction were not far beyond the capacity of the human intellect. The physicist's renunciation of completeness for his cosmos is therefore not a matter of fundamental principle.

The state of mind which enables a man to do work of this kind is akin to that of the religious worshiper or the lover; the daily effort comes from no deliberate intention or program, but straight from the heart.

In the temple of science are many mansions, and various indeed are they that dwell therein and the motives that have led them thither. Many take to science out of a joyful sense of superior intellectual power; science is their own special sport to which they look for vivid experience and the satisfaction of ambition; many others are to be found in the temple who have offered the products of their brains on this altar for purely utilitarian purposes. Were an angel of the Lord to come and drive all the people belonging to these two categories out of the temple, the assemblage would be seriously depleted, but there would still be some men, of both present and past times, left inside. Our Planck is one of them, and that is why we love him. I am quite aware that we have just now lightheartedly expelled in imagination many excellent men who are largely, perhaps chiefly, responsible for the buildings of the temple of science; and in many cases, our angel would find it a pretty ticklish job to decide. But of one thing I feel sure: if the types we have just expelled were the only types there were, the temple would never have come to be, any more than a forest can grow which consists of nothing but creepers. For these people any sphere of human activity will do if it comes to a point; whether they become engineers, officers, tradesmen, or scientists depends on circumstances.Now let us have another look at those who have found favor with the angel. Most of them are somewhat odd, uncommunicative, solitary fellows, really less like each other, in spite of these common characteristics, than the hosts of the rejected. What has brought them to the temple? That is a difficult question and no single answer will cover it.

The most simple picture one can form about the creation of an empirical science is along the lines of an inductive method. Individual facts are selected and grouped together such that their lawful connection becomes clearly apparent. ... The truly great advances in our understanding of nature originated in a manner almost diametrically opposed to induction. The intuitive grasp of the essentials or a large complex of facts leads the scientist to the postulation of a hypothetical basic law, or several such basic laws. From the basic laws (system of axioms) he derives his conclusions as completely as possible in a purely logically deductive manner. These conclusions, derived from the basic laws (and often only after time-consuming developments and calculations), can then be compared to experience, and in this manner provide criteria for the justification of the assumed basic law.

I lie on the beach like a crocodile and let myself be roasted by the sun. I never see a newspaper and don't give a damn for what is called the world.

"The physical world is real." That is supposed to be the fundamental hypothesis. What does "hypothesis" mean here? For me, a hypothesis is a statement, whose truth must be assumed for the moment, but whose meaning must be raised above all ambiguity. The above statement appears to me, however, to be, in itself, meaningless, as if one said: "The physical world is cock-a-doodle-do." It appears to me that the "real" is an intrinsically empty, meaningless category (pigeon hole), whose monstrous importance lies only in the fact that I can do certain things in it and not certain others.

The most beautiful fate of a physical theory is to point the way to the establishment of a more inclusive theory, in which it lives on as a limiting case.

We shall, therefore, assume the complete physical equivalence of a gravitational field and a corresponding acceleration of the reference system.

If A is success in life, then A = x + y + z. Work is x, play is y and z is keeping your mouth shut.

Science is international but its success is based on institutions, which are owned by nations. If therefore, we wish to promote culture we have to combine and to organize institutions with our own power and means.

How can it be that mathematics, being, after all, a product of human thought which is independent of experience, is so admirably appropriate to the objects of reality? Is human reason, then, without experience, merely by taking thought, able to fathom the properties of real things?

Whereas materialistic historians and philosophers neglect psychic realities, Freud is inclined to overstress their importance. I am not a psychologist, but it seems to me fairly evident that physiological factors, especially our endocrines, control our destiny ... I am not able to venture a judgment on so important a phase of modern thought. However, it seems to me that psychoanalysis is not always salutary. It may not always be helpful to delve into the subconscious. The machinery of our legs is controlled by a hundred different muscles. Do you think it would help us to walk if we analyzed our legs and knew exactly which one of the little muscles must be employed in locomotion and the order in which they work? ... I am not prepared to accept all his [Freud's] conclusions, but I consider his work an immensely valuable contribution to the science of human behavior. I think he is even greater as a writer than as a psychologist. Freud's brilliant style is unsurpassed by anyone since Schopenhauer.

I believe with Schopenhauer: We can do what we wish, but we can only wish what we must. Practically, I am, nevertheless, compelled to act as if freedom of the will existed. If I wish to live in a civilized community, I must act as if man is a responsible being. I know that philosophically a murderer is not responsible for his crime; nevertheless, I must protect myself from unpleasant contacts. I may consider him guiltless, but I prefer not to take tea with him.

I am a determinist. As such, I do not believe in free will. The Jews believe in free will. They believe that man shapes his own life. I reject that doctrine philosophically. In that respect, I am not a Jew.

We are inclined to overemphasize the material influences in history. The Russians especially make this mistake. Intellectual values and ethnic influences, tradition and emotional factors are equally important. If this were not the case, Europe would today be a federated state, not a madhouse of nationalism.

In America, more than anywhere else, the individual is lost in the achievements of the many. America is beginning to be the world leader in a scientific investigation. American scholarship is both patient and inspiring. The Americans show an unselfish devotion to science, which is the very opposite of the conventional European view of your countrymen. Too many of us look upon Americans as dollar chasers. This is a cruel libel, even if it is reiterated thoughtlessly by the Americans themselves. It is not true that the dollar is an American fetish. The American student is not interested in dollars, not even in success as such, but in his task, the object of the search. It is his painstaking application to the study of the infinitely little and the infinitely large which accounts for his success in astronomy.

Our time is Gothic in its spirit. Unlike the Renaissance, it is not dominated by a few outstanding personalities. The twentieth century has established the democracy of the intellect. In the republic of art and science, there are many men who take an equally important part in the intellectual movements of our age. It is the epoch rather than the individual that is important. There is no one dominant personality like Galileo or Newton. Even in the nineteenth century, there were still a few giants who outtopped all others. Today the general level is much higher than ever before in the history of the world, but there are few men whose stature immediately sets them apart from all others.

Reading after a certain age diverts the mind too much from its creative pursuits. Any man who reads too much and uses his own brain too little falls into lazy habits of thinking, just as the man who spends too much time in the theater is tempted to be content with living vicariously instead of living his own life.

If I was not a physicist, I would probably be a musician. I often think in music. I live my daydreams in music. I see my life in terms of music. ... I cannot tell if I would have done any creative work of importance in music, but I do know that I get most joy in life out of my violin.

I refuse to make money out of my science. My laurel is not for sale like so many bales of cotton.

Sometimes one pays most for the things one gets for nothing.

The meaning of relativity has been widely misunderstood. Philosophers play with the word, like a child with a doll. Relativity, as I see it, merely denotes that certain physical and mechanical facts, which have been regarded as positive and permanent, are relative with regard to certain other facts in the sphere of physics and mechanics. It does not mean that everything in life is relative and that we have the right to turn the whole world mischievously topsy-turvy.

One reason why mathematics enjoys special esteem, above all other sciences, is that its laws are absolutely certain and indisputable, while those of other sciences are to some extent debatable and in constant danger of being overthrown by newly discovered facts.

Everything should be made simple as possible but no simpler.