Not all things worth counting are countable and not all things that count are worth counting.

We will never be able to solve the problems of tomorrow with the thinking of today

That is the way to learn the most, that when you are doing something with such enjoyment that you don't notice that the time passes.

The stakes are immense, the task colossal, the time is short. But we may hope - we must hope - that man's own creation, man's own genius, will not destroy him.

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.

If I were wrong, wouldn't one be enough?

My deep religiosity [...] found an abrupt ending at the age of twelve, through the reading of popular scientific books.