Let there be light, says the Bible. All the firmaments of technology, all our computers and networks, are built with light, and of light, and for light, to hasten its spread around the world. Light glows on the telescom's periphery; it shines as its core; it illuminates its webs and its links. From Newton, Maxwell, and Einstein to Richard Feynman and Charles Townes, the more men have gazed at light, the more it turns out to be a phenomenon utterly different from anything else. And yet everything else - every atom and every molecula - is fraught with its oscillating intensity.