Thinking in its lower grades, is comparable to paper money, and in its higher forms it is a kind of poetry.

Liberty is always unfinished business

Even the most scientific investigator in science, the most thoroughgoing Positivist, cannot dispense with fiction; he must at least make use of categories, and they are already fictions, analogical fictions, or labels, which give us the same pleasure as children receive when they are told the "name" of a thing.

At the present day the crude theory of the sexual impulse held on one side, and the ignorant rejection of theory altogether on the other side, are beginning to be seen as both alike unjustified.

Education, whatever else it should or should not be, must be an inoculation against the poisons of life and an adequate equipment in knowledge and skill for meeting the chances of life.

It is here [in mathematics] that the artist has the fullest scope of his imagination.

There is held to be no surer test of civilization than the increase per head of the consumption of alcohol and tobacco. Yet alcohol and tobacco are recognizable poisons, so that their consumption has only to be carried far enough to destroy civilization altogether.