In the 1600s the Dutch used to cover their mirrors with curtains when not in use, lest the reflectivenesss be used up.
In ancient China reflective pieces of polished brass were placed over doorknobs so that evil spirits would scare themselves away.
Ben Franklin mounted mirrors outside his second-story window so he could secretly see who was knocking at his front door.
Building managers install mirrors in lobbies because people complain less about waiting for slow elevators when they’re occupied looking at themselves.
In 1994, Russian astronauts orbiting in the Mir spacecraft tried using mirrors to reflect sunlight into northern areas of their country, in an attempt to lengthen the short growing season. It didn’t work.