# Sun Tzu's five classes of spy, and what they do in SaaS > Sun Tzu named five kinds of informant in the last chapter of The Art of War. All five are still working. A comic, and where each one turns up in your market. *The Art of War* has 13 chapters. The last one is not about war. It is about paying people to tell you things. Sun Tzu sorts those people into five classes and ranks them. Two and a half thousand years later all five are still working. They have better clothes now, and most of them do it in public without being asked. ![Six-panel noir comic titled The 5 Classes of Spies by Sun Tzu, filed as CTC-2026/01. The cover cell is a parchment page reading Sun Tzu, The Art of War, ch. 13, as observed in the modern SaaS market, above the quote: To remain ignorant of the enemy's condition simply because one grudges a hundred pieces of silver is the height of inhumanity. Panel 1, Local spies 因間: a dog detective in a trench coat and hat takes notes in a rainy diner booth while a crow in a raincoat talks with his hands, a hedgehog and a cat waiting behind him. Caption: Local spies. The people who live in the enemy's district. Today they leave reviews. Nobody has to be asked twice. Panel 2, Inward spies 內間: a squirrel in a suit points at a slide reading OUR Q3 ROADMAP stamped INTERNAL, while a dog films the screen on a tripod camera from the back of the dark room. Caption: Inward spies. The enemy's own officials. Today they give talks. They post job ads. They write changelogs. Panel 3, Converted spies 反間: a dog studies a comparison board headed US vs. COMPETITOR TRACKER with ticks down one column and red crosses down the other, while a rat in shirtsleeves sleeps face down on the desk beside a shopping bag marked CI Heroes and Co. Caption: Converted spies. The enemy's spies, turned around. Your rival already built a page comparing themselves to you. They did the work. We read it. Panel 4, Doomed spies 死間: a raccoon in a hat opens a briefcase holding a document headed ROADMAP, Q1 competitive intelligence on blockchain, stamped CONFIDENTIAL, as a figure walks away under a streetlamp in the rain. Caption: Doomed spies. Sent out with false news, not expected back. Some companies still announce a direction they never intended to take. It works once. Panel 5, Surviving spies 生間: a beagle wearing a CI INTERN badge slumps exhausted in a chair at trade-show booth 412, holding an apple and a fistful of pens, while the dog detective pats his head and waves an expense report stamped APPROVED. Caption: Surviving spies. The ones who come back and report. Your own people, at the booth and in the bake-off. Dull work. Still useful.](/img/comics/ctc-2026-01.png) *CTC-2026/01. Filed under things that have not changed since the fifth century BC.* ## The art of using spies, according to Sun Tzu Chapter 13 is the last one, and its title is "The Use of Spies" (用間). Sun Tzu does the sums first. An army of 100,000 men, marching a "thousand li" (about 400 kilometres), costs a "thousand ounces of silver" a day. It keeps 700,000 families from their fields. > Hostile armies may face each other for years, striving for the victory which is decided in a single day. This being so, to remain in ignorance of the enemy's condition simply because one grudges the outlay of a hundred ounces of silver in honours and emoluments, is the height of inhumanity. > > — Sun Tzu, chapter 13, in Lionel Giles's 1910 translation A hundred ounces against a thousand a day. He is asking why a commander would pay the second and refuse the first. The next line is the whole pitch, written down before anyone had a pricing page. Foreknowledge cannot be had from spirits, from omens, from analogy with past events or from calculation. It has to come from people who know the enemy's situation. You cannot derive it. You have to go and look. Then he names the five, and says they should be the best paid men in the army. That last part is what panel five is about. - **Local spies** (因間), drawn from the people of the enemy's district. - **Inward spies** (內間), the enemy's own officials. - **Converted spies** (反間), the enemy's spies, working for you. - **Doomed spies** (死間), sent out carrying things you want the enemy to believe. - **Surviving spies** (生間), the ones who come back with news. ## The five classes, in current clothes ### Local spies · 因間 Local spies are the people who live in the enemy's district. Sun Tzu meant villagers and merchants, the ones who know which roads flood because they walk them. Today they are your competitors' customers. You never have to approach them. They are already "talking," on the record and at length. Review sites. Subreddits. The support forum where somebody posts a screenshot of a bill they were not expecting. Old threads that still rank. It costs nothing and it never stops. Worth doing. It is the class everyone already has access to and almost nobody reads on a schedule. ### Inward spies · 內間 Inward spies are the enemy's own officials. Sun Tzu meant officers on the other side's payroll, which is the part of the chapter that has aged worst. The modern version needs no recruiting, because your rival's staff publish constantly and their employer signs it off. Conference talks. Job ads that name the stack and the team being built. Changelogs, release notes, an engineer writing up an architecture on a personal blog. All voluntary, all public, all legal. Do it, and be precise about what it is. You are reading what they chose to publish. Approaching someone's current employees is a different activity with a different name, and [Rippling and Deel](https://techcrunch.com/2026/01/23/the-rippling-deel-corporate-spying-scandal-may-have-taken-another-wild-turn/) are now spending more on lawyers over it than a century of reading each other's changelogs would have cost. (Sun Tzu would laugh at the bill. He priced this exact problem at a hundred ounces of silver.) ### Converted spies · 反間 Converted spies are the enemy's spies, turned around. Sun Tzu ranks this class first of the five and his reason is structural. What you learn from the converted spy is what lets you find, recruit and run the other four. The modern version is the page your rival wrote about you. It tells you which of your strengths worries them enough to argue with, and which weakness they think they can win the deal on. They paid for that research and published the conclusion for free. A strong one, and not often used. The trick is reading the page the week they change it rather than the week you remember it exists. ### Doomed spies · 死間 Doomed spies are sent out carrying false news and are not expected back. Sun Tzu is describing a man who repeats something he believes to be true, gets caught, and is killed for it. It is the part of the chapter that stops it being a business book. One descendant is defensible. Canary tokens, watermarked documents and seeded records tell you when your material has been copied or scraped, and nobody gets hurt when they fire. The strategic version is announcing a direction you never intend to take, and we do not recommend it. It works once. Your audience is your own customers, your press and your analysts as much as the rival you aimed it at, and all of them keep receipts. ### Surviving spies · 生間 Surviving spies are the ones who come back and report. Sun Tzu means the ordinary returning agent, the class the whole system rests on. Today that is your own people doing unglamorous recurring work. The booth at the trade show. The bake-off you lost, and the win/loss call two weeks after it. A free trial of the rival product, opened once a quarter by somebody who writes down what changed since last time. Worth doing, and the class most likely to quietly stop happening. Nobody gets promoted for filing the same report every month. Sun Tzu saw that problem coming and answered it with money. ## A hundred ounces of silver The arithmetic has not changed. A company will spend a year of engineering on a feature nobody asked for, then decline to spend a small and boring amount finding out what is already happening around it. Sun Tzu had a phrase for that. He was not being polite. *— C. T. Lucky* --- Source: https://competitortracker.io/blog/sun-tzu-five-classes-of-spy/ Updated: 2026-08-22