I cannot favour laws such as that of Idaho, which allows sterilization of 'mental defectives, epileptics, habitual criminals, moral degenerates, and sex perverts.' The last two categories here are very vague . . . The law of Idaho would have justified the sterilization of Socrates, Plato, Julius Caesar, and St. Paul.

Uncertainty in the pressure of vivid hopes and fears is painful, but must be endured if we wish to live without the support of comforting fairy tales.

Almost everything that distinguishes the modern world from earlier centuries is attributable to science, which achieved its most spectacular triumphs in the seventeenth century.

The human race may well become extinct before the end of the century.

Perhaps the best hope for the future of mankind is that ways will be found of increasing the scope and intensity of sympathy.

The rules of logic are to mathematics what those of structure are to architecture.

When I say that children should be told about sex, I do not mean that they should be told only the bare physiological facts; they should be told whatever they wish to know. There should be no attempt to represent adults as more virtuous than they are, or sex as occurring only in marriage. There is no excuse for deceiving children. And when, as must happen in conventional families, they find that their parents have lied, they lose confidence in them, and feel justified in lying to them.