p63. Mathematics, rightly viewed, possesses not only truth, but supreme beauty --- a beauty cold and austere, like that of sculpture, without appeal to any part of our weaker nature, without the gorgeous trappings of painting or music, yet sublimely pure, and capable of a stern perfection such as only the greatest art can show.
p76. mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true.
p71. The method of "postulating" what we want has many advantages; they are the same as the advantages of theft over honest toil. Let us leave them to others and proceed with our honest toil. (from Chapter VII: Rational, Real, and Complex Numbers)
p104. One should as a rule respect public opinion in so far as is necessary to avoid starvation and to keep out of prison, but anything that goes beyond this is voluntary submission to an unnecessary tyranny, and is likely to interfere with happiness in all kinds of ways. (from Ch. 9: Fear of Public Opinion )
p160. To be able to fill leisure intelligently is the last product of civilization, and at present very few people have reached this level. (from Ch. 14: Work )
p111. Aristotle, in spite of his reputation, is full of absurdities. ... He tells us that the blood of females is blacker than that of males; ... ; that women have fewer teeth than men, and so on.
p115. Aristotle could have avoided the mistake of thinking that women have fewer teeth than men, by the simple device of asking Mrs. Aristotle to keep her mouth open while he counted. He did not do so because he thought he knew.
p116. 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. If some one maintains that two and two are five, or that Iceland is on the equator, you feel pity rather than anger, unless you know so little of arithmetic or geography that his opinion shakes your own contrary conviction. The most savage controversies are those about matters as to which there is no good evidence either way. Persecution is used in theology, not in arithmetic, because in arithmetic there is knowledge, but in theology there is only opinion.