War can protect; it cannot create.

It is impossible to meditate on time and the mystery of nature without an overwhelming emotion at the limitations of human intelligence.

The true method of discovery is like the flight of an aeroplane. It starts from the ground of particular observation; it makes a flight in the thin air of imaginative generalization; and it again lands for renewed observation rendered acute by rational interpretation.

Without adventure all civilization is full of decay. Adventure rarely reaches its predetermined end. Columbus never reached China.

We must not expect simple answers to far-reaching questions. However far our gaze penetrates, there are always heights beyond which block our vision.

Art is the imposing of a pattern on experience.

It is a profoundly erroneous truism, repeated by all copy books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilization advances by extending the number of important operations which we can perform without thinking about them.