Emmanuel Romeuf

One of the oldest proclamations in Western literature—maybe the very oldest, depending on how you see things—is “Let there be light.” And for most of human history, whether we dwelled in caves or in Gilded Age mansions, light was inseparable from heat: Domestic lighting consisted of either letting sunlight inside or burning something organic. The Egyptians were making candles from beeswax and animal fat 5,000 years ago, and except for the discovery of new fuel sources—whale oil, ahoy!—the candle continued to illuminate homes deep into the 19th century.