Bertrand Russell

The degree of one's emotions varies inversely with one's knowledge of the facts - the less you know, the hotter you get.

Most of the greatest evils that man has inflicted upon man have come through people feeling quite certain about something which, in fact, was false.

Fear is the main source of superstition, and one of the main sources of cruelty. To conquer fear is the beginning of wisdom, in the pursuit of truth as in the endeavor after a worthy manner of life.

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

4. Form The "form" of a proposition is that, in it, which remains unchanged when every constituent of the proposition is replaced by another.

5. a priori Logical propositions are such as can be known a priori without study of the actual world.

Conventional people are roused to fury by departure from convention, largely because they regard such departure as a criticism of themselves.

Those who in principle oppose birth control are either incapable of arithmetic or else in favour of war, pestilence and famine as permanent features of human life.

Calculus required continuity, and continuity was supposed to require the infinitely little; but nobody could discover what the infinitely little might be.

Sanity calms, but madness is more interesting.