Real knowledge is to know the extent of one's ignorance.

Better keep yourself clean and bright; you are the window through which you must see the world.

Life consists not in holding good cards but in playing those you hold well.

It is harder to conceal ignorance than to acquire knowledge.

Humility and knowledge in poor clothes excel pride and ignorance in costly attire.

Having knowledge but lacking the power to express it clearly is no better than never having any ideas at all.

Knowledge has to be improved, challenged, and increased constantly, or it vanishes.

The true sign of intelligence is not knowledge but imagination.

Opinion is the medium between knowledge and ignorance.

A man of knowledge lives by acting, not by thinking about acting.