“Know the enemy and know yourself.
Your victory will be painless."
Sun Tzu’s The Art of War 10:5.15-16
The two lines above appear rather late in Sun Tzu's work, the tenth chapter out of thirteen. At this point in the book, every term in these lines has a very specific definition. To understand these lines, you must first be familiar with the concepts "to know," "enemy," "victory," and "pain."