“Never try to discourage thinking, for you are sure to succeed.”

“The Ten Commandments that, as a teacher, I should wish to promulgate, might be set forth as follows:1- Do not feel absolutely certain of anything.2- Do not think it worth while to proceed by concealing evidence, for the evidence is sure to come to light.3- Never try to discourage thinking for you are sure to succeed.4- When you meet with opposition, even if it should be from your husband or your children, endeavor to overcome it by argument and not by authority, for a victory dependent upon authority is unreal and illusory.5- Have no respect for the authority of others, for there are always contrary authorities to be found.6- Do not use power to suppress opinions you think pernicious, for if you do the opinions will suppress you.7- Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric.8- Find more pleasure in intelligent dissent than in passive agreement, for, if you value intelligence as you should, the former implies a deeper agreement than the latter.9- Be scrupulously truthful, even if the truth is inconvenient, for it is more inconvenient when you try to conceal it.10- Do not feel envious of the happiness of those who live in a fool’s paradise, for only a fool will think that it is happiness.”

“Never let yourself be diverted, either by what you wish to believe, or what you think could have beneficent social effects if it were believed; but look only and solely at what are the facts.”

“Your writing is never as good as you hoped; but never as bad as you feared.”

“Everything is vague to a degree you do not realize till you have tried to make it precise.”

“It seems to me a fundamental dishonesty, and a fundamental treachery to intellectual integrity to hold a belief because you think it's useful and not because you think it's true.”

“Many a man has borne himself proudly on the scaffold; surely the same pride should teach us to think truly about man's place in the world. Even if the open windows of science at first make us shiver after the cosy indoor warmth of traditional humanising myths, in the end the fresh air brings vigour, and the great spaces have a splendour of their own.”