In a sense, knowledge shrinks as wisdom grows, for details are swallowed up in principles. The details for knowledge which are important, will be picked up ad hoc in each avocation of life, but the habit of the active utilization of well-understood principles is the final possession of WISDOM.

From the very beginning of his education, the child should experience the joy of discovery.

Life is an offensive, directed against the repetitious mechanism of the Universe.

Through and through the world is infested with quantity: To talk sense is to talk quantities. It is no use saying the nation is large. . . . How large? It is no use saying the radium is scarce. . . . How scarce? You cannot evade quantity. You may fly to poetry and music, and quantity and number will face you in your rhythms and your octaves.

The many become one and are increased by one.

Not ignorance, but ignorance of ignorance, is the death of knowledge.

The real history does not get written, because it is not in people's brains but in their nerves and vitals.