No one demands more caution than a spy, and when someone has the skeleton key to minds, counter him by leaving the key of caution inside, on the other side of the keyhole.
Baltasar GracianWatchfulness is the only guard against cunning. Be intent on his intentions. Many succeed in making others do their own affairs, and unless you possess the key to their motives you may at any moment be forced to take their chestnuts out of the fire to the damage of your own fingers.
Baltasar Gracian