and therefore reason about its own state. Intercession is the ability of a program to modify its own execution state or alter its own interpretation or meaning. - Daniel G. Bobrow et al. 11 If you know your enemies and know yourself, you can win a hundred battles without a single loss. If you only know yourself, but not your opponent, you may win or may lose. If you know neither yourself nor your enemy, you will always endanger ourself. - Sun Tzu, The Art of War, 6th Century BC