If you know, say you know. If you don't know, say you don't know.
What you do not want done to yourself, do not do to others.
The gentleman is calm and at ease. The gentleman is dignified but not proud; the small man is proud but not dignified.
He who learns but does not think, is lost. He who thinks but does not learn is in great danger.
You do not understand even life. How can you understand death?
A man is great not because he hasn't failed; a man is great because failure hasn't stopped him.