Metaphor matters because it opens the door to discovery. Whenever we solve a problem, or make a discovery, we compare what we know with what we don't know. And the only way to find out about the latter is to investigate the ways it might be like the former. Einstein described his scientific method as combinatory play. He famously used thought experiments, which are essentially elaborate analogies, to come up with some of his greatest discoveries. By bringing together what we know and what we don't know through analogy, metaphorical thinking strikes the spark that ignites discovery. Now metaphor is ubiquitous, yet it's hidden. But you just have to look at the words around you and you'll find it. Ralph Waldo Emerson described language as "fossil poetry." But before it was fossil poetry language was fossil metaphor. And these fossils still breathe.