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.

In a logically perfect language, there will be one word and no more for every simple object, and everything that is not simple will be expressed by a combination of words, by a combination derived, of course, from the words for the simple things that enter in, one word for each simple component.

I mean by intellectual integrity the habit of deciding vexed questions in accordance with the evidence, or of leaving them undecided where the evidence is inconclusive. This virtue, though it is underestimated by almost all adherents of any system of dogma, is to my mind of the very greatest social importance and far more likely to benefit the world than Christianity or any other system of organized beliefs.

They must often change, who would be constant in happiness or wisdom. Those who continually search for happiness will never find it. Happiness is made, not found. To be without some of the things you want is an indispensable part of happiness.

Ordinary language is totally unsuited for expressing what physics really asserts, since the words of everyday life are not sufficiently abstract. Only mathematics and mathematical logic can say as little as the physicist means to say.

Life and hope for the world are to be found only in the deeds of love.

What science cannot discover, mankind cannot know.