For thousands of years, getting light was a huge hassle. You had to make candles from scratch. This is not as romantic as it sounds. You had to get a cow, raise the cow, feed the cow, kill the cow, get the fat out of the cow, cook the fat, dip wicks into the fat. All that--for not very much light. Now, if we want to light a whole room, we just flip a switch.

The history of light explains why the world today is the way it is. It explains why we aren't all subsistence farmers, and why we can afford to have artists and massage therapists and plumbers. (And, yes, people who make podcasts about the history of light.) The history of light is the history of economic growth--of things getting faster, cheaper, and more efficient.

On today's show: How we got from dim little candles made out of cow fat, to as much light as we want at the flick of a switch.

Today's show was hosted by Jacob Goldstein and David Kestenbaum. It was originally produced by Caitlin Kenney and Damiano Marchetti. Today's rerun was produced by James Sneed, and edited by Jenny Lawton. It was fact-checked by Sierra Juarez. Engineering by Valentina Rodríguez Sánchez. Alex Goldmark is Planet Money's executive producer.

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