Saadi (1184 – 1291), Persian poet
Nothing is so good for an ignorant man as silence; and if he was sensible of this he would not be ignorant.
Roam abroad in the world, and take thy fill of its enjoyments before the day shall come when thou must quit it for good.
Reveal not every secret you have to a friend, for how can you tell but that friend may hereafter become an enemy. And bring not all mischief you are able to upon an enemy, for he may one day become your friend.
