The secret of change is to focus all of your energy, not on fighting the old, but on building the new.

Ignorance, the root and stem of all evil.

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.

Where there is shouting, there is no true knowledge.

Death may be the greatest of all human blessings.

An honest man is always a child.

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

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