Genius always finds itself a century too early.

Human behavior flows from three main sources: desire, emotion, and knowledge.

All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.

All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.

Success is never final, failure is never fatal. It's courage that counts.

The true sign of intelligence is not knowledge but imagination.

You cannot open a book without learning something.

Satisfaction consists in freedom from pain, which is the positive element of life.

The difference between stupidity and genius is that genius has its limits.

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