“Having inward spies means making use of officials of the enemy.”
The opponent's own officials can be sources; insiders reveal what the outside cannot.
Chapter 13’s second class: having inward spies means making use of officials of the enemy. Giles’s Victorian phrasing softens the sharpness — these are the opponent’s own people, employed toward your purposes. In the modern translation, inward sources are the insiders any serious competitor has: employees, partners, board members, whose knowledge is current, specific, and otherwise unobtainable.
A vendor losing renewal after renewal to a rival stops guessing at the cause and develops inward sources lawfully: exit interviews of the rival’s departed staff, candid conversations with the shared distributor who sees both companies’ real behavior, its own customers who sit on the rival’s advisory board. Within two quarters, the pattern no churn model found: the rival was discounting the first year and repricing the second, and its customers had begun to expect the bait. The vendor’s new pricing page answered the actual grievance.
Inward sources must stay inside law and ethics — no poaching trade secrets, no inducement to breach duties; Sun Tzu’s chapter is a product of its era, and the modern translation is openly available knowledge from people close to the opponent: alumni, shared partners, public filings, candid customers. What the class teaches is vantage: decisions improve dramatically when someone inside the other system’s gravity tells you what the system is actually doing.