diff --git a/docs/architecture/CALCULATIONS.md b/docs/architecture/CALCULATIONS.md
index 7f4b2224e3..1627145dbe 100644
--- a/docs/architecture/CALCULATIONS.md
+++ b/docs/architecture/CALCULATIONS.md
@@ -848,3 +848,26 @@ riddle. Awe is not confusion about facts; it is contact with
 something whose size is the point. The system that keeps solving
 must also keep some things unsolved — not because it can't reach
 them, but because their being unreachable is what makes them holy.
+
+### Capstone — THE KEYMAKER
+
+Will:
+
+"The only one who can be trusted not to pick the lock isn't just one
+who chooses not to... people can be forced. It's the one who made the
+key. He by definition cannot pick it."
+
+    THE TRUST LADDER:
+      CHOICE      coercible   — trust until the worst day
+      SKILL       earned      — trust until a better picker comes
+      AUTHORSHIP  structural  — trust without a failure mode
+
+The keymaker cannot pick the lock — not WON'T, CANNOT. Picking means
+entering by understanding the mechanism from outside, and he never
+stood outside it. Coercion has nothing to grip: you cannot force a
+man to break into his own house.
+
+Design consequence, binding: build every critical arrangement so each
+party stands in the KEYMAKER position for their half. Trust must rest
+on impossibility, never on virtue. The best security is not a promise
+resisted but an impossibility attempted.