Hu Tao: Illusory Fortifications

King Wu asked Tai Gong: 

"How can one discern the虚实 (empty-solid) of enemy fortifications and detect their troop movements?"

Tai Gong replied: 

"A commander must comprehend three realms: above, the顺逆 (favorable-adverse) of celestial timing; below, the险易 (perilous-accessible) of earthly terrain; between, the得失 (gains-losses) of human affairs. Ascend heights to observe enemy maneuvers; survey their ramparts from afar to discern虚实; watch their soldiers' bearing to know their deployments."

King Wu asked: 

"By what signs can this knowledge be obtained?"

Tai Gong answered: 

"When drums beat without rhythm and bells ring without order; when birds perch undisturbed on their walls and no dust clouds rise—this reveals an empty camp manned by straw dummies. If enemies withdraw hastily yet soon return chaotically, their command chain has ruptured. Where disorder reigns in troop movements, formations crumble. Strike such chaos swiftly—though outnumbered, victory shall be yours."