Brief and powerless is man's life; on him and all his race the slow, sure doom falls pitiless and dark.

The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.

When we perceive any object of a familiar kind, much of what appears subjectively to be immediately given is really derived from past experience.

Science, by itself, cannot supply us with an ethic. It can show us how to achieve a given end, and it may show us that some ends cannot be achieved.

All human activity is prompted by desire.

It is false to suggest that men must turn away from his desires in the interest of a higher duty. Men only responds to duty if he desires to do so. To understand men, you must understand their desires and the relative strength of those desires.

Belief in a Divine mission is one of the many forms of certainty that have afflicted the human race.