Those who are not shocked when they first come across quantum theory cannot possibly have understood it.

Every sentence I utter must be understood not as an affirmation, but as a question.

It is a great pity that human beings cannot find all of their satisfaction in scientific contemplativeness.

Anyone who is not shocked by quantum theory has not understood it.

Some subjects are so serious that one can only joke about them.

Truth and clarity are complementary.

It is not enough to be wrong, one must also be polite.

Never express yourself more clearly than you are able to think.

I go into the Upanishads to ask questions.

No, no, you are not thinking, you are just being logical.

How wonderful that we have met with a paradox. Now we have some hope of making progress.

Every valuable human being must be a radical and a rebel, for what he must aim at is to make things better than they are.

Physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods of ordering and surveying human experience. In this respect our task must be to account for such experience in a manner independent of individual subjective judgement and therefore objective in the sense that it can be unambiguously communicated in ordinary human language.

We must be clear that when it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images and establishing mental connections.

The grand discoveries which scientific experiment yielded at and about the turn of the century, in which investigators in many countries took an eminent part and which were destined all unexpectedly to give us a fresh insight into the structure of atoms, were due in the first instance, as all are aware, to the work of the great investigators of the English school, Sir Joseph Thomson and Sir Ernest Rutherford, who have inscribed their names on the tablets of the history of scientific research as distinguished witnesses to the truth that imagination and acumen are capable of penetrating the crowded mass of registered experience and of revealing Nature's simplicity to our gaze.

Even the mathematical framework helps nothing, I would first like to understand how Nature avoids the contradictions.

The great extension of our experience in recent years has brought light to the insufficiency of our simple mechanical conceptions and, as a consequence, has shaken the foundation on which the customary interpretation of observation was based.

Isolated material particles are abstractions, their properties being definable and observable only through their interaction with other systems.

What is it that we humans depend on? We depend on our words... Our task is to communicate experience and ideas to others. We must strive continually to extend the scope of our description, but in such a way that our messages do not thereby lose their objective or unambiguous character ... We are suspended in language in such a way that we cannot say what is up and what is down. The word "reality" is also a word, a word which we must learn to use correctly.

For a parallel to the lesson of atomic theory regarding the limited applicability of such customary idealizations, we must in fact turn to quite other branches of science, such as psychology, or even to that kind of epistemological problems with which already thinkers like Buddha and Lao Tzu have been confronted, when trying to harmonize our position as spectators and actors in the great drama of existence.

However far the phenomena transcend the scope of classical physical explanation, the account of all evidence must be expressed in classical terms. The argument is that simply by the word "experiment" we refer to a situation where we can tell others what we have done and what we have learned and that, therefore, the account of the experimental arrangement and of the results of the observations must be expressed in unambiguous language with suitable application of the terminology of classical physics.

An expert is a person who has found out by his own painful experience all the mistakes that one can make in a very narrow field.

I am absolutely prepared to talk about the spiritual life of an electronic computer: to state that it is reflecting or is in a bad mood... The question whether the machine really feels or ponders, or whether it merely looks as though it did, is of course absolutely meaningingless.