Ignorance, the root and stem of all evil.

Think good, and good follows. Think evil, and evil follows. You are what you think all day long.

The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.

I am not an Athenian or a Greek, but a citizen of the world.

Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.

The most important knowledge is that which guides the way you lead your life.

If you can't explain it to a six year old, you don't understand it yourself.

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

Strong minds discuss ideas, average minds discuss events, weak minds discuss people