Energy

This chapter answers a question of scale: how can a commander control an enormous force as if it were a few men? Sun Tzu's answer is organization. "The control of a large force is the same in principle as the control of a few men: it is merely a question of dividing up their numbers." Fighting with a large army is no different from fighting with a small one once it is a matter of signs and signals — banners and flags for the eye, gongs and drums for the ear — that let a host move as one body.

The engine of the chapter is the pairing of the direct (zheng) and the indirect (qi). The direct method holds the enemy in place; the indirect secures victory. Their combinations are inexhaustible: "In battle there are not more than two methods of attack — the direct and the indirect — yet these two in combination give rise to an endless series of manoeuvres." They are like a circle with no beginning and no end, like the five musical notes that yield more melodies than can ever be heard, the five primary colours that produce more hues than can ever be seen, the five tastes that combine into more flavours than can ever be tasted. From a handful of elements comes limitless variation, and the side that masters the interplay can never be exhausted.

Sun Tzu then captures the two ingredients of a decisive blow: momentum and timing. "The quality of decision is like the well-timed swoop of a falcon which enables it to strike and destroy its victim." Energy may be likened to the bending of a crossbow; decision, to the releasing of the trigger. Onset is like the rush of pent-up water rolling stones along in its course — overwhelming force concentrated and released at the exact instant.

Crucially, he locates strength in the combined energy of the formation rather than in the heroism of individuals. The clever combatant "looks to the effect of combined energy, and does not require too much from individuals." He chooses his men and then lets the situation do the work, "and the energy thus developed carries his men along with it." Men whose courage has been kindled by momentum are like logs or stones — motionless on flat ground, in motion on a slope; round, they roll without stopping.

The closing image is the source of one of the book's enduring metaphors: the energy of good fighting troops is "as the momentum of a round stone rolled down a mountain thousands of feet in height." The practical lesson for any organization is that performance is mostly structural. Build the right formation, time the release, and let momentum carry ordinary people to extraordinary results — do not demand heroics from individuals when you can engineer unstoppable force from the system itself.