A bartender gets an order from a waitress: a vodka and soda, a glass of house red, a martini up, and a mojito. What does he do? He lays out the four different kinds of glass that the drinks require in a row, so he doesn’t have to remember them. If another order comes in while he is working on the first, he lays out more glasses. In this way, the sequence of orders, as well as the content of each order, is represented in a spatial arrangement that is visible at a glance. It is in the world, rather than in his head. This is good, because there is only so much room in his head.
