We do not like to be robbed of an enemy; we want someone to hate when we suffer. It is so depressing to think that we suffer because we are fools; yet, taking mankind in the mass, that is the truth.

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.

What is best in mathematics deserves not merely to be learnt as a task, but to assimilated as a part of daily thought, and brought again and again before the mind with ever-renewed encouragement.

The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd.

Human nature is so constructed that it gives affection most readily to those who seem least to demand it.

Science is what you know, philosophy is what you don't know.

A process which led from the amoeba to man appeared to the philosophers to be obviously a progress though whether the amoeba would agree with this opinion is not known.