In warfare, there are no constant conditions. He who can modify his tactics in relation to his opponent will succeed and win.

If this is long delayed, weapons are blunted and morale depressed.

the leader of armies is the arbiter of the people's fate, the man on whom it depends whether the nation shall be in peace or in peril.

Spies cannot be usefully employed without a certain intuitive sagacity; They cannot be properly managed without benevolence and straightforwardness; Without subtle ingenuity of mind, one cannot make certain of the truth of their reports; Be subtle! be subtle! and use your spies for every kind of warfare; If a secret piece of news is divulged by a spy before the time is ripe, he must be put to death together with the man to whom the secret was told.

One who speaks deferentially but increases his preparations will advance. One who speaks belligerently and advances hastily will retreat.

If your opponent is of choleric temper, seek to irritate him. Pretend to be weak, that he may grow arrogant.

What enables the wise sovereign and the good general to strike and conquer, and achieve things beyond the reach of ordinary men, is foreknowledge.