“Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric.”

“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.”

“The opinions that are held with passion are always those for which no good ground exists; indeed the passion is the measure of the holders lack of rational conviction. Opinions in politics and religion are almost always held passionately.”

“If an opinion contrary to your own makes you angry, that is a sign that you are subconsciously aware of having no good reason for thinking as you do.”

“Happiness is promoted by associations of persons with similar tastes and similar opinions.”

“Freedom of opinion can only exist when the government thinks itself secure.”

“I have been accused of a habit of changing my opinions. I am not myself in any degree ashamed of having changed my opinions. What physicist who was already active in 1900 would dream of boasting that his opinions had not changed during the last half century? In science men change their opinions when new knowledge becomes available; but philosophy in the minds of many is assimilated rather to theology than to science. The kind of philosophy that I value and have endeavoured to pursue is scientific, in the sense that there is some definite knowledge to be obtained and that new discoveries can make the admission of former error inevitable to any candid mind. For what I have said, whether early or late, I do not claim the kind of truth which theologians claim for their creeds. I claim only, at best, that the opinion expressed was a sensible one to hold at the time when it was expressed. I should be much surprised if subsequent research did not show that it needed to be modified. I hope, therefore, that whoever uses this dictionary will not suppose the remarks which it quotes to be intended as pontifical pronouncements, but only as the best I could do at the time towards the promotion of clear and accurate thinking. Clarity, above all, has been my aim.”