Without adventure civilization is in full decay. ... The great fact [is] that in their day the great achievements of the past were the adventures of the past.

How the past perishes is how the future becomes.

The only use of knowledge of the past is to equip us for the present.

Systems, scientific or philosophic, come and go. Each method of limited understanding is at length exhausted. In its prime each system is a triumphant success: in its decay it is an obstructive nuisance.

The tragedy of the world is that those who are imaginative have but slight experience, and those who are experienced have feeble imaginations.

It is a safe rule to apply that, when a mathematical or philosophical author writes with a misty profundity, he is talking nonsense.

Religion is what the individual does with his own solitariness.