... on principle, it is quite wrong to try founding a theory on observable magnitudes alone. In reality the very opposite happens. It is the theory which decides what we can observe.
I must try, however, as best I can, although I am very conscious of the fact that our feelings and strivings are often contradictory and obscure and that they cannot be expressed in easy and simple formulas.
A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port, together with some of the surrounding territory.
The real difficulty, the difficulty which has baffled the sages of all times, is rather this: how can we make our teaching so potent in the motional life of man, that its influence should withstand the pressure of the elemental psychic forces in the individual?
When the nazis came to power, I looked to the universities that prided themselves upon their intellectual freedom, and they failed me. I looked to the German press, which prided itself on the freedom of the press, and it failed me. Until at last the churches stood alone, and that for which I once had little regard earned my respect.
While you're trying to get ahead, remember to get aheart as well. When your only problem IS a nail, all you want is a decent hammer. There are only two ways to live your life: one is as though nothing is a miracle; the other is as though everything is a miracle.
[Newton wrote to Halley ... that he would not give Hooke any credit] That, alas, is vanity. You find it in so many scientists. You know, it has always hurt me to think that Galileo did not acknowledge the work of Kepler.