The Golden Mean
Aristotle called it the golden mean: virtue not as a fixed rule but as the balanced center between two failures, one of deficiency and one of excess. Courage, in his accounting, sits between cowardice and recklessness — not an average of the two, but the harder discipline of holding neither.
Everything cataloged after this point in the record — the streams, the app, Affirm Mode and Question Mode, the arch metaphor itself — is that same idea, inherited rather than invented, applied to a single life instead of a whole ethics. The mean came first. Keystone is what happened when someone tried to build an instrument for holding it.