An investment in knowledge pays the best interest.

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.

Opinion is the medium between knowledge and ignorance.

If the facts don't fit the theory, change the facts.

Study without desire spoils the memory, and it retains nothing that it takes in.

I am indebted to my father for living, but to my teacher for living well.

The progressive development of man is vitally dependent on invention.

Investigate, educate and organize.

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

It isn't what we don't know that gives us trouble, it's what we know that ain't so.

I decided to teach because I think that any person who studies philosophy has to be involved actively.

I cannot teach anybody anything. I can only make them think

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

Physics is like sex: sure, it may give some practical results, but that's not why we do it.

One test of the correctness of educational procedure is the happiness of the child.

It is beyond a doubt that all our knowledge begins with experience.

A thought is an idea in transit.

Integrity without knowledge is weak and useless, and knowledge without integrity is dangerous and dreadful.

Education is a human right with immense power to transform. On its foundation rest the cornerstones of freedom, democracy and sustainable human development.

Real learning comes about when the competitive spirit has ceased.

Better know nothing than half-know many things.