四輕二重一信
Four Lightnesses, Two Weights, One Trust
武侯問曰:“進兵之道何先?”
起對曰:“先明四輕、二重、一信。”
曰:“何謂也?”
對曰:“使地輕馬,馬輕車,車輕人,人輕戰。明知險易,則地輕馬;芻秣以時,則馬輕車;膏鐧有餘,則車輕人;鋒銳甲堅,則人輕戰。進有重賞,退有重刑,行之以信。審能達此,勝之主也。”
Marquis Wu asked: "What is the first priority in advancing troops?"
Wu Qi replied: "First clarify the Four Lightnesses, Two Weights, and One Trust."
"What do these mean?"
Wu Qi replied: "Make the terrain light for the horses, the horses light for the chariots, the chariots light for the men, and the men light for battle. When you clearly understand which terrain is dangerous and which is easy, the terrain becomes light for the horses. When fodder and grain are supplied on time, the horses become light for the chariots. When axle grease and fittings are abundant, the chariots become light for the men. When blades are sharp and armor is strong, the men become light for battle. Advance earns heavy reward; retreat earns heavy punishment — and both are administered with absolute reliability. If you can truly achieve this, you hold the key to victory."
Notes
'Light' (輕) here means 'easy for' or 'responsive to' — the idea is an optimized chain where each element enables the next. The 'Two Weights' are heavy rewards for advancing and heavy punishments for retreating. The 'One Trust' (一信) is reliability in carrying out both.
