³⁰For example, the walking speed in a busy store: if you go too fast, you crash into everybody, causing you to slow down. If you walk too slowly, everybody crashes into you, or steps on your heels; hence you start walking a bit faster. The important things here are: the difference (speed) and the impact of this difference (bruises) cause you to act. In an abandoned city street, there is no correction factor, allowing you to walk as fast as you’d like.