Unless you really understand others, you can hardly attain your own self-understanding.

Know your enemy, know his sword.

Thirdly, the gentleman warrior, carrying the weaponry of his way. The way of the warrior is to master the virtue of his weapons. If a gentleman dislikes strategy he will not appreciate the benefit of weaponry, so must he not have a little taste for this?

If you fail to take advantage of your enemies' collapse, they may recover.

If the enemy thinks of the mountains, attack like the sea; and if he thinks of the sea, attack like the mountains.

If you want to learn the craft of war, ponder over this book. The teacher is as a needle, the disciple is as thread. You must practice constantly.

Even if a man has no natural ability, he can be a warrior.