Planet Money
Planet Money

The history of light (classic)

November 4, 2026

AI Summary

5 min read

The history of light (classic)

Jacob Goldstein, co-host of Planet Money, opens with a confession: there is one episode he co-hosted years ago that he still thinks about at least once a week. The heart of that episode is the biggest lesson he learned covering economics: the pie can get bigger. It is at least theoretically possible for everybody to be better off. The economist whose work anchors the show is Bill Nordhaus, who later won the Nobel Prize for his work on the economics of climate change. Last week, Nordhaus died at age 85. This episode is a rerun in his memory.

What a day's wages bought in ancient Babylon

The episode begins with a visceral demonstration. Goldstein buys two pounds of beef fat from a butcher, melts it on his stove, and spends about 45 minutes dipping twine wicks into the hot grease. The result: six tiny, crooked, smelly candles. He brings them into the office, where the writer Jane Brox, author of Brilliant: The Evolution of Artificial Light, inspects them. "If a mother was trying to teach her daughter to make candles," Brox says, "she would not be pleased with these candles." But when they light one, it works. "Dude, you made a candle."

Continue reading the full summary in the app — free to try.

Read Full Summary →

Free • No credit card required

Listen to Audio Summary Open in App

What you'll learn

  • 1 (01:00) **The Candle-Making Experiment** - Jacob Goldstein tries to make candles from beef fat to demonstrate how difficult and expensive light was for most of human history
  • 2 (03:09) **Why Light History Explains Modern Prosperity** - The hosts frame the episode: the story of light shows how economic growth freed humanity from subsistence farming
  • 3 (05:23) **Expert Jane Brox on Pre-Modern Light Sources** - The author of *Brilliant: The Evolution of Artificial Light* reacts to the homemade candles and describes historical alternatives
  • 4 (07:56) **Bill Nordhaus’s Light Price Index** - Economist Bill Nordhaus created a method to measure the cost of light across thousands of years
  • 5 (10:01) **The Babylonian Baseline: 10 Minutes of Light** - In ancient Babylon, a day’s labor bought only 10 minutes of light from a dim bulb
  • 6 (11:00) **4,000 Years of Stagnation** - From Babylon to 1800, there were only tiny improvements in light and the economy
  • 7 (12:16) **The 1800s Breakthrough: Kerosene** - Around 1800, the pace of improvement in light suddenly accelerated, with kerosene as a major milestone

+ Full timestamped outline available in the app

Show Notes

How do you measure human progress? Light is the answer.

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.

Nobel-winning economist Bill Nordhaus passed away last week. He was known for his work on the economics of climate change, but he also came up with this idea that the history of light explains reveals 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. It shows us the pie can get bigger, sometimes, there can be a type of progress where everyone is better off. 

On today's show, one of our all time favorites: 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, and how that is a measure of what economic progress means. 

(Note: This episode originally ran in 2014.)

Read: 

Follow: 

Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include bonus episodes and sponsor-free listening. Learn more at plus.npr.org.

Today's show was hosted by Jacob Goldstein and David Kestenbaum. It was originally produced by Caitlin Kenney and Damian
Planet Money

More from this podcast

Planet Money →