Such a small thing, really — two pieces of glass and a tube no longer than the span of a man’s arm. The first telescope that Galileo built (and I don’t mean he was the first to build one, for surely he wasn’t) played tricks with distance and size. The device transported faraway objects into the viewer’s presence, and magnified them there. As Galileo demonstrated to the Doge of Venice in 1609, even an entity invisible to the naked eye, such as an enemy ship on the horizon, would loom large within the purview of his spyglass. Later, alone in the dark, after he’d learned how to gr... (p. 16)