Regard as your most faithful friends, not those who praise everything you say or do, but those who criticize your mistakes.

Spend your leisure time in cultivating an ear attentive to discourse, for in this way you will find that you learn with ease what others have found out with difficulty.

Whetstones are not themselves able to cut, but make iron sharp and capable of cutting.

Oratory is good only if it has the qualities of fitness for the occasion, propriety of style, and originality of treatment, while in the case of letters there is no such need whatsoever.

Be gracious to all men, but choose the best to be your friends.

Make no man your friend before inquiring how he has used his former friends; for you must expect him to treat you as he has treated them. Be slow to give your friendship, but when you have given it, strive to make it lasting; for it is as reprehensible to make many changes in one's associates as to have no friends at all. Neither test your friends to your own injury nor be willing to forego a test of your companions.

Conduct yourself towards your parents as you would have your children conduct themselves towards you.