Today's friends are tomorrow's enemies.
World history has also proved that it is true the other way round: today's enemies are tomorrow's friends.
When it comes to self interests, there is no friend.
When somebody offers you some help, think about what would happen if one day s/he became your rival, opponent, or enemy?
A wise person has no enemies, and knows how to deal with different kinds of friends in various situations.
There is nothing to fear, but fear itself.
If you know your opponent's strengths and weaknesses, you have won the game at least 50%.
United, you'll win.
