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

The only true wisdom is in knowing you know nothing.

The more I see, the less I know for sure.

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

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.

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

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