Hundreds of years ago, the great Italian city of Florence was very dark at night. No streetlamps or billboards cast up their glow. No floodlights shone down on baseball fields. When the sky grew dusky, the streets filled with shadows and the bustling city noises disappeared. The river Arno reflected the stars overhead as it flowed past the lamplit houses. In a mansion close to the river, a boy named Amerigo leaned out his window, tipping his head back to look at the stars…