Mind, Body, Soul
Formation vs Vulnerability
In ancient times, skillful warriors first made themselves invincible and then watched for vulnerability in their opponents. Making yourself invincible means knowing yourself; waiting for vulnerability in opponents means knowing others.
Invincibility is in oneself, vulnerability is in the opponent. If opponents have no formation to find out, no gap or slack to take advantage of, how can one overcome them even when equipped? Invincibility is a matter of defense and vulnerability is a matter of attack, (The Art of War/Sun Tzu, translated by Thomas Cleary, 1991).