Perhaps the most powerful revolutions are the ones that deny they ever happened. They install a new approach and erase an earlier practice so successfully that we look at the world through the structures they leave behind.

It happened improvisationally, indeed probably unintentionally. Participants solved one problem and created others; they reacted as often as they acted affirmatively; they moved by experience and intuition, without an overarching theory; and the whole affair took decades, involved many different actors, and coheres largely in retrospect.