“If you know the enemy and know yourself, you need not fear the result of a hundred battles.”Sun Tzu · The Art of War
Deep knowledge of oneself and the opponent guarantees victory without the need for battle.
Sun Tzu said a skilled general wins the war before the battle even starts, through good positioning, accurate information, and patience. Fighting directly, with brute force, was for him the last option, not the first. Deep knowledge of your own weaknesses mattered just as much as knowing the enemy.
Why it matters The book is used today far beyond the military, in business negotiations and sports strategy.