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.

Every addition to true knowledge is an addition to human power.

Freedom means the opportunity to be what we never thought we would be.

The best advice I ever got was that knowledge is power and to keep reading.

The best way to cheer yourself up is to try to cheer somebody else up.

Knowledge is love and light and vision.

We aim above the mark to hit the mark.

Knowledge rests not upon truth alone, but upon error also.

Education is the movement from darkness to light.

Knowledge is the eye of desire and can become the pilot of the soul.

Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning.

There are two ways of spreading light: to be the candle or the mirror that reflects it.

Knowledge is only one-half. Faith is the other.

Even the knowledge of my own fallibility cannot keep me from making mistakes. Only when I fall do I get up again.

There are three principal means of acquiring knowledge... observation of nature, reflection, and experimentation. Observation collects facts; reflection combines them; experimentation verifies the result of that combination.

I don't pretend we have all the answers. But the questions are certainly worth thinking about.

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

Formula for success: rise early, work hard, strike oil.

I have never in my life learned anything from any man who agreed with me.

Cherish that which is within you, and shut off that which is without; for much knowledge is a curse.

It is one of my sources of happiness never to desire a knowledge of other people's business.

But inner experience is only one source of human knowledge.

Every addition to true knowledge is an addition to human power.

There are no shortcuts in evolution.

Knowledge is like money: to be of value it must circulate, and in circulating it can increase in quantity and, hopefully, in value.

Opinion is the medium between knowledge and ignorance.

The greater our knowledge increases the more our ignorance unfolds.

Where there is no vision, there is no hope.

Be not simply good - be good for something.

Knowledge is power. Information is power. The secreting or hoarding of knowledge or information may be an act of tyranny camouflaged as humility.

Gratitude is the fairest blossom which springs from the soul.

The true method of knowledge is experiment.

Give light and people will find the way.

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

Every addition to true knowledge is an addition to human power.

I am not afraid of tomorrow, for I have seen yesterday and I love today!

Even the knowledge of my own fallibility cannot keep me from making mistakes. Only when I fall do I get up again.

Challenging the meaning of life is the truest expression of the state of being human.

Rough diamonds may sometimes be mistaken for worthless pebbles.

There is no influence like the influence of habit.

Nothing can be done except little by little.

The knowledge of anything, since all things have causes, is not acquired or complete unless it is known by its causes.

Silence is the sleep that nourishes wisdom.

Have patience. All things are difficult before they become easy.

It is harder to conceal ignorance than to acquire knowledge.

The possession of knowledge does not kill the sense of wonder and mystery. There is always more mystery.

Cherish that which is within you, and shut off that which is without; for much knowledge is a curse.