To realize the unimportance of time is the gate to wisdom.

Always remember that true happiness is not in getting what you want, but wanting what you already have. He who dies with the most toys is still dead. What is wanted is not the will to believe, but the will to find out, which is the exact opposite.

Mathematics takes us into the region of absolute necessity, to which not only the actual word, but every possible word, must conform.

Although this may seem a paradox, all exact science is dominated by the idea of approximation. When a man tells you that he knows the exact truth about anything, you are safe in inferring that he is an inexact man. Every careful measurement in science is always given with the probable error ... every observer admits that he is likely wrong, and knows about how much wrong he is likely to be.

Not to be absolutely certain is, I think, one of the essential things in rationality.

We know very little, and yet it is astonishing that we know so much, and still more astonishing that so little knowledge can give us so much power.

Citizens as conceived by governments are persons who admire the status quo and are prepared to exert themselves for its preservation. Oddly enough, while all governments aim at producing men of this type to the exclusion of all other types, their heroes in the past are of exactly the sort that they aim at preventing in the present. Americans admire George Washington and Jefferson, but imprison those who share their political opinions.