Only idiots refuse to change their minds.

In a good bookroom you feel in some mysterious way that you are absorbing the wisdom contained in all the books through your skin, without even opening them.

The only real mistake is the one from which we learn nothing.

One who gains strength by overcoming obstacles possesses the only strength which can overcome adversity.

Promises are like crying babies in a theater, they should be carried out at once.

The ultimate authority must always rest with the individual's own reason and critical analysis.

If you have no problems, then you have no clue to what is going.

Throw your heart over the fence and the rest will follow.

None but ourselves can free our minds.

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

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

He that cannot reason is a fool. He that will not is a bigot. He that dare not is a slave.

Think no vice so small that you may commit it, and no virtue so small that you may over look it.

Forget not that the earth delights to feel your bare feet and the winds long to play with your hair.

Be sure you put your feet in the right place, then stand firm.

Life's battles don't always go to the stronger or faster man. But sooner or later, the man who wins is the man who thinks he can.

Yesterday I was clever, so I wanted to change the world. Today I am wise, so I am changing myself.

Nature is pleased with simplicity. And nature is no dummy

The one you buy will be the only one that doesn't work.

The object of the superior man is truth.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.