It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one's balance.

[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.

I wouldn't want to live if I did not have my work. In any case, it's good that I'm already old and personally don't have to count on a prolonged future.

If at first the idea is not absurd, then there is no hope for it.

It is little short of a miracle that modern methods of instruction have not already completely strangled the holy curiosity of inquiry.... I believe that one could even deprive a healthy beast of prey of its voraciousness if one could force it with a whip to eat continuously whether it were hungry or not.

If I would be a young man again and had to decide how to make my living, I would not try to become a scientist or scholar or teacher. I would rather choose to be a plumber or a peddler in hope to find that modest degree of independence still available under present circumstances.

Truly novel inventions emerge only in one's youth. Later one becomes ever more experienced, famous-and foolish.