The more you look at 'common knowledge', the more you realise that it is more likely to be common than it is to be knowledge. No real knowledge is common.
Idries ShahThere is a Persian proverb: 'To test that which has been tested is ignorance.' To try to test something without the means of testing is even worse.
Idries ShahIf you give what can be taken, you are not really giving. Take what you are given, not what you want to be given. Give what cannot be taken.
Idries ShahYou need not wonder whether you should have an unreliable person as a friend. An unreliable person is nobody's friend.
Idries Shah