Our rate of progress is such that an individual human being, of ordinary length of life, will be called on to face novel situations which find no parallel in his past. The fixed person, for the fixed duties, who, in older societies was such a godsend, in the future will be a public danger.

Speak out in acts; the time for words has passed, and only deeds will suffice.

The fact of the religious vision, and its history of persistent expansion, is our one ground for optimism. Apart from it, human life is a flash of occasional enjoyments lighting up a mass of pain and misery, a bagatelle of transient experience.

Civilization advances by extending the number of important operations which we can perform without thinking of them.

The aim of science is to seek the simplest explanation of complex facts... Seek simplicity and distrust it.

Nature, even in the act of satisfying anticipation, often provides a surprise.

Speech is human nature itself, with none of the artificiality of written language.