To make a discovery is not necessarily the same as to understand a discovery.

A number of current theoretical explorations will turn out to be passing fancies...

[Heisenberg's seminal 1925 paper initiating quantum mechanics marked] one of the great jumps—perhaps the greatest—in the development of twentieth century physics.

Of course, relative citation frequencies are no measure of relative importance. Who has not aspired to write a paper so fundamental that very soon it is known to everyone and cited by no one?

Once I even took the train to Utrecht, forty miles from Amsterdam, with my yellow star, this star which I still have. Why did I go? I just wanted to visit some friends. I was a little bit crazy, a little bit insane.

One of the absolute rules I learned in the war was, don't know anything you don't need to know, because if you ever get caught they will get it out of you.

I knew all the time I was going to get through the war. It was completely irrational, a silly idea, but I was not going to lie down and get myself killed. I was going to get out of it.

I spent every night until four in the morning on my dissertation, until I came to the point when I could not write another word, not even the next letter. I went to bed. Eight o'clock the next morning I was up writing again.

There is not a soul on Earth who can read the deluge of physics publications in its entirety. As a result, it is sad but true that physics has irretrievably fallen apart from a cohesive to a fragmented discipline. ... It was not that long ago that people were complaining about two cultures. If we only had it that good. today.

[George] Uhlenbeck was a highly gifted physicist. One of his remarkable traits was he would read every issue of T%he Physical Review from cover to cover.

One of the things I learned, one of the strangest things, is how to think. There was nothing else to do. I couldn't see people, or go for a walk in the forest. All I had was my head and my books, and I thought a lot.

Deliberately or not, every author is of course present in every book he or she writes - even in a scientific text.

The rule of the game was never assume that anybody, however honorable, would be able to stand up under torture. If Mr. X, who knew where I was, was caught for some reason, I should move.

To make a discovery is not necessarily the same as to understand a discovery. Not only Planck but also other physicists were intially at a loss as to what the proper context of the new postulate really was.