“These military devices, leading to victory, must not be divulged beforehand.”
Revealing your plan lets the other side adapt for free; secrecy preserves the edge of surprise.
The catalogue ends by sealing itself: these military devices, leading to victory, must not be divulged beforehand. Sun Tzu closes the stratagem list with the handling instructions — the tricks work by surprise, and surprise has a shelf life that disclosure spends. The verse also guards the list as a whole: an opponent who knows your catalogue can count its entries against you.
A firm pre-announces a platform change with a two-quarter runway — customers, partners, and competitors all briefed early for "ecosystem alignment." The runway is the leak: competitors ship the change first, partners re-negotiate around it, and the announcement’s advantage is fully consumed before the product exists. The same change, announced with the release, kept its surprise and its terms. Identical strategy; the disclosure schedule decided it.
Non-divulgation is not institutional secrecy — Chapter 5 built the signals that let your own army execute; the verse seals the devices against the opponent, not the troops against their general. And "beforehand" is the operative word: after the strike lands, disclosure is free and often mandatory. The discipline governs the window between conception and effect — which is exactly the window strategy most loves to talk about.