<p>Nowadays, we are surrounded by instruments that display the time. Clocks are on the walls of our buildings, and watches are worn on our bodies. We carry in our pockets sophisticated smart phones whose default display setting is to show the time. Whether it is on the dashboards of our cars or the screens of our computers, on bus shelters or airport departure boards, on alarms by our bedside or on appliances in our kitchens, the precise minute, or even second, is almost always close at hand.&nbsp;</p> <p>Medieval people - by contrast - lived before mechanically measured time was a feature of everyday life.&nbsp;</p>