The consequences of a plethora of half-digested theoretical knowledge are deplorable.

Religion is the reaction of human nature to its search for God.

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

But you can catch yourself entertaining habitually certain ideas and setting others aside; and that, I think, is where our personal destinies are largely decided.

Civilization advances by extending the number of important operations which we can perform without thinking about them. Operations of thought are cavalry charges in a battle - they are limited in number, they require fresh horses, and must only be made at decisive moments.

There is a technique, a knack, for thinking, just as there is for doing other things. You are not wholly at the mercy of your thoughts, any more than they are you. They are a machine you can learn to operate.

When success turns a man's head he faces failure