the ones here function more like departure points for sets of skillfully interwoven narratives. To take the example of glass, we begin with a formation of molten silica, probably by a crashing comet, 26 million years ago in the Libyan desert. In due course we move to the glassmakers of Venice in the 13th century. And then things get more interesting. Monks laboring over religious manuscripts find that curved pieces of glass can aid their vision; a few centuries later, spectacles become popular, because parts of the European population, in response to the invention of the printing press, discover they need corrective lenses to read these new things called books. In time come telescopes and microscopes, which bring forth revolutionary ideas about stars and germs. Fiberglass eventually arrives, and soon we figure out how to make fiber optic glass cables, which carry pulses of laser light and zip petabytes of data around the globe.