Joy and sorrow, beauty and deformity, equally pass away.
He who is indifferent to the suffering of others is a traitor to that which is truly human.
Reveal not every secret you have to a friend, for how can you tell but that friend may hereafter become and enemy. And bring not all mischief you are able to upon an enemy, for he may one day become your friend.
The stranger has no friend, unless it be a stranger.
Inflict not on an enemy every injury in your power, for he may afterwards become your friend.
However much you study, you cannot know without action. A donkey laden with books is neither an intellectual nor a wise man. Empty of essence, what learning has he whether upon him is firewood or book?