The fullness of knowledge only comes through the awareness of ignorance.

The deepest sin against the human mind is to believe things without evidence.

There is nothing more notable in Socrates than that he found time, when he was an old man, to learn music and dancing, and thought it time well spent.

Reading is to the mind what exercise is to the body.

I cannot live without books.

If you're teaching today what you were teaching five years ago, either the field is dead or you are.

The progressive development of man is vitally dependent on invention.

The man who does not read good books has no advantage over the man who can't read them.

Never help a child with a task at which he feels he can succeed.

There is one quality which one must possess to win, and that is definiteness of purpose, the knowledge of what one wants, and a burning desire to possess it.

No power and no treasure can outweigh the extension of our knowledge.

Medicine is my lawful wife and literature my mistress; when I get tired of one, I spend the night with the other.

Books! I dunno if I ever told you this, but books are the greatest gift one person can give another.

He who would learn to fly one day must first learn to stand and walk and run and climb and dance; one cannot fly into flying.

Better know nothing than half-know many things.

Science is what we have learned about how to keep from fooling ourselves.

What is freedom of expression? Without the freedom to offend, it ceases to exist.

It is not enough for the teacher to love the child. She must first love and understand the universe. She must prepare herself, and truly work at it.

There is nothing more awful, insulting, and depressing than banality.

The whole of science is nothing more than a refinement of everyday thinking.

Opinion is the medium between knowledge and ignorance.