Hence that general is skilful in attack whose opponent does not know what to defend; and he is skilful in defense whose opponent does not know what to attack.
When strong, avoid them. If of high morale, depress them. Seem humble to fill them with conceit. If at ease, exhaust them. If united, separate them. Attack their weaknesses. Emerge to their surprise.
Foreknowledge cannot be gotten from ghosts and spirits, cannot be had by analogy, cannot be found out by calculation. It must be obtained from people, people who know the conditions of the enemy.
When one treats people with benevolence, justice, and righteoousness, and reposes confidence in them, the army will be united in mind and all will be happy to serve their leaders.
It is only the enlightened ruler and the wise general who will use the highest intelligence of the army for the purposes of spying, and thereby they achieve great results.
