He who learns, and makes no use of his learning, is a beast of burden with a load of books. Does the ass comprehend whether he carries on his back a library or a bundle of faggots?
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.
A friend whom you have been gaining during your whole life, you ought not to be displeased with in a moment. A stone is many years becoming a ruby – take care that you do not destroy it in an instant against another stone.
