SUN ZI said: Generally, management of a large force is the same in principle as the management of a few men: it is a matter of organization. And to direct a large army to fight is the same as to direct a small one:  it is a matter of command  signs and signals.  That the whole army can sustain the enemy's all-out attack without suffering defeat is due to operations of extraordinary and normal forces. Troops thrown against the enemy as a grindstone  against eggs is an example of the strong beating the weak.

  Generally, in battle, use the normal force to engage and use the extraordinary to win.  Now, to a commander adept at the use of extraordinary forces, his resources are as infiinite as the heaven and earth, as inexhaustible as the flow of the running rivers.  They end and begin again like the motions of the sun and moon.  They die away and then are reborn like the changing of the four seasons. There are not more than five musical notes, but the various combinations of the five notes bring about more melodies than can ever be heard.  There are not more than five basic pigments,  yet in blending them together it is possible to produce more colours than can ever be seen.  There are not more than five cardinal tastes, but the mixture of the five yields more flavours than can ever be tasted. In battle, there are not more than two kinds of postures--operation of the extraordinary force and operation of the normal force, but their combinations give rise to an endless series of manoeuvres. For these two forces are  mutually reproductive.  It is like moving in circle, never coming to an end.  Who can exhaust the possibilities of their combinations?

    When torrential water tosses boulders, it is because of its momentum; when the strike of a hawk breaks the body of its prey, it is because of timing.  Thus, in battle, a good commander creates a posture releasing an irresistible and  overwhelming momentum, and his attack is precisely timed in a quick tempo.  The energy is similar to a fully drawn crossbow; the timing, the release of the trigger.

    Amid turmoil and tumult of battle, there may be seeming disorder and yet no real disorder in one's own troops.  In the midst of confusion and chaos,  your troops appear to be milling about in circles, yet it is proof against defeat.

    Apparent disorder is born of order;  apparant cowardice, of courage;  apparent weakness, of strength.  Order or disorder depends on organization and direction; courage or cowardice on postures; strength or weakness on dispositions.

    Thus, one who is adept at keeping the enemy on the move maintains deceitful appearances, according to which the enemy will act.  He lures with something that the enemy is certain to take. By so doing he keeps the enemy on the move and then waits for the right moment to make a sudden ambush with picked troops.

    Therefore, a skilled commander sets great store by using the situation to the best advantage, and does not make excessive demand on his subordinates.  Hence he is able to select right men and exploits the situation. He who takes advantage of the situation uses his men in fighting as rolling logs or rocks.  It is the nature of logs and rocks to stay stationary on the flat ground, and to roll forward on a slope.  If four-cornered, they stop; if round-shaped, they roll. Thus, the energy of troops skilfully commanded is just like the momentum of round rocks quickly tumbling down from a mountain thousands of feet in height.  This is what 'use of energy' means.