JACOB GOLDSTEIN, HOST:

Long before there were light bulbs, there was fat. For thousands of years, if you wanted to light up your cave, your mud hut or if you were really lucky your castle, you had to find some fat, something to use for a wick - maybe some moss, maybe a piece of fabric - and you had to light it on fire. This was not easy. Even today, it's a hard way to get light.

(SOUNDBITE OF PHONE RINGING)

UNIDENTIFIED MAN #1: (Unintelligible).

GOLDSTEIN: Yeah, hi, do you sell fat, maybe beef fat?

UNIDENTIFIED MAN #1: No. No, I don't carry that. No.

GOLDSTEIN: OK, thanks very much.

UNIDENTIFIED MAN #1: Thank you.

GOLDSTEIN: Hi. Do you sell fat, like beef fat...

UNIDENTIFIED MAN #2: No, we don't sell any of that.

GOLDSTEIN: Suet?

UNIDENTIFIED WOMAN: No.

GOLDSTEIN: OK.

UNIDENTIFIED MAN #2: OK.

GOLDSTEIN: Thanks very much.

UNIDENTIFIED MAN #3: Cito's (ph).

GOLDSTEIN: Yeah, hi. Do you sell beef fat?

UNIDENTIFIED MAN #3: Yeah, yeah, that we have all the time.

GOLDSTEIN: How much is that?

UNIDENTIFIED MAN #3: 2.98 a pound.

GOLDSTEIN: OK, great. Thanks very much.

UNIDENTIFIED MAN #3: You're welcome, bye.

GOLDSTEIN: I got two pounds. A big nasty lump of fat came from around the cow's kidney. I got some twine from the hardware store. And I went home to my apartment to try and make candles.

It's a little harder to chop than you might think, kind of sticks to itself.

I put the fat on the stove.

It's pretty melted. It smells really nasty. It's like animal nasty.

I strained it, then I started dipping the wicks into it.

We're dipping, we're dipping.

You have to let the fat dry, then you have to dip the wick some more.

More dipping.

It was maybe, I don't know, 45 minutes or so of dipping.

Dip, dip.

I got kind of dip crazy in there.

Dip, dip.

After hours of work, not counting raising the cow or killing the cow or making the twine, I had six tiny, crooked, smelly candles. Hello and welcome to PLANET MONEY. I'm Jacob Goldstein.

DAVID KESTENBAUM, HOST:

And I'm David Kestenbaum. Today on the show, the story of 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 I don't think I'm exaggerating here. This one little story, it explains why we are where we are today, why billions of people don't have to worry about starving today, why we aren't all subsistence farmers, why we can afford to have artists and massage therapists and plumbers and, yes, radio reporters doing stories about the history of light.

KESTENBAUM: Jacob, you brought these scraggly little candles in the office. I'm holding them up here. They look...

(LAUGHTER)

KESTENBAUM: ...They look a little gnarled.

GOLDSTEIN: They're definitely not straight. And they're not, like, sleek.

KESTENBAUM: No, it looks like some mold has grown on a...

GOLDSTEIN: On a string.

KESTENBAUM: ...On a string.

GOLDSTEIN: Yeah.

KESTENBAUM: Yeah. So you brought these candles into the office here, and we wanted to show them to an expert. And we sat down with this woman, Jane Brox. Jane wrote a book called "Brilliant: The Evolution Of Artificial Light."

GOLDSTEIN: So I made a few different candles. I tried...

JANE BROX: Oh, look, they're beautiful (laughter).

GOLDSTEIN: If by beautiful you mean a total disaster.

BROX: In the olden days if a mother was trying to teach her daughter to make candles, she would not be pleased with these candles. But we'll see what happens.

KESTENBAUM: I was afraid when we lit these things that we might set off the fire alarm or the sprinkler system in the office. I mean, that is how weird it is to have light from fire these days.

GOLDSTEIN: I was afraid we weren't going to be able to light them at all. I mean, it's just beef fat and twine. But we pulled out a lighter.

(SOUNDBITE OF LIGHTER IGNITING)

BROX: Oh, we have - we have light. That's not too bad. Should we see how long it lasts?

GOLDSTEIN: It's not pretty, but I'm very impressed.

BROX: It's a beautiful color. Look at the nice, yellow flame, wouldn't you say?

GOLDSTEIN: Doody (ph) made a candle.

Jane says that the quest for this, for something that gives you light after the sun goes down, drove people to ll kinds of things.

KESTENBAUM: In the United States in the Pacific Northwest, Native Americans used dried salmon. They basically made a salmon candle. In the tropics, people would catch fireflies and try to make a kind of firefly lantern. And then there's this bird called the petrel.

BROX: The storm petrel in the north of Scotland, where they would just - which is a very oily seabird, which they'd catch and dry and thread a wick down its throat and then light it. And then that was a lamp.

KESTENBAUM: Just carry around a dead bird with a...

KESTENBAUM: Well, it would be on a table (laughter). And I would imagine they'd have a little storage area with a lot of dead storm petrels (laughter). Martha, we need another petrel (laughter). The petrel supply is getting low.

GOLDSTEIN: These ways of making light were all a huge hassle. They took a lot of work. It was not just that I didn't know what I was doing when I made those candles. The writer Harriet Beecher Stowe said making candles from animal fat was seven times as bad as washing clothes.

KESTENBAUM: I mean, think about it, you've got to get a cow. You've got to raise the cow. You've got to have food to feed the cow. You've got to kill the cow. You've got to get the fat out of the cow. You've got to put the fat in your Cuisinart.

GOLDSTEIN: Which isn't going to be invented for a hundred years.

KESTENBAUM: From an economic perspective, if you want to try to quantify how much of pain in the butt it is to make something or at least how hard it is to get that thing, you can ask a simple question. How much does it cost?

Bill Nordhaus, an economist at Yale, awhile back got obsessed with this question. He decided he wanted to calculate exactly how expensive light was thousands of years ago, and how that cost changed over time. Because light, you know, light is this thing society has needed and sought forever. It was a way to track progress, not just in light, but in all kinds of things.

Unfortunately, in order to , he needed to know how much things cost thousands of years ago, like in ancient Babylon. He wasn't even sure those numbers existed, but they did.

BILL NORDHAUS: I ran into a woman at Yale. And she, believe it or not, you - it's just unbelievable, actually. She actually had wage data and price data from the Babylonian era, so 4,000 years ago.

GOLDSTEIN: (Laughter).

So now he has these numbers. But he needs to know one other thing. How much light are people getting for their money? In ancient Babylon, people used lamps for light. So Nordhaus decided to make one.

NORDHAUS: I did this in my dining room, where else?

GOLDSTEIN: He buys an ancient-style lamp from a catalog. He gets it burning. To measure how bright it is, he borrows a light meter from a facilities guy at Yale and he does some science.

NORDHAUS: And I would just measure it and write it down, just the way you see in the old movies, some guy with - in his lab coat writing down the measurements.

KESTENBAUM: Jacob, a odd little note here, I happened to be taking Nordhaus's Economics class right around this time, which I would say was a pretty serious, like, no-nonsense class. And it is so funny for me to think that at night he was going home and measuring ancient lamp light in his dining room with a light meter.

GOLDSTEIN: So he does this, the light meter and the ancient lamp. And he has his numbers. But now he has to figure out a way to compare the price of light over thousands of years.

KESTENBAUM: So here's one measure he uses. If you take a day's wages, you work all day, you take all the money you earn in that day, and you spend it on light. How many minutes could you light up a small room at night with as much light as you get from today's modern light bulb? Here's the answer for ancient Babylon.

NORDHAUS: Maybe 10 minutes. It was really expensive.

KESTENBAUM: An entire day's wages got you the equivalent of 10 minutes of light from a kind of dim light bulb. Economists talk a lot about productivity, how much one person can produce with a day's labor. And back then the answer was not much. I mean, everything was hard. Growing food was hard. Making candles, for instance, took hours. And they used up fat. Fat, which by the way, was expensive because raising animals was hard.

GOLDSTEIN: This was a world where when the sun went down, almost everyone lived in the dark. And this may sound sort of romantic, but basically it was awful. The dark was not some beautiful thing you went out and explored. It was dangerous. It was something that trapped you. In Paris at one point, there was actually a law that said every night everybody has to give their keys to a magistrate, go home and lock themselves in the house.

KESTENBAUM: And for basically 4,000 years, very little happens with light or with the economy in general. Most people work all day and that gets them enough to eat. The way things get better, the way an economy grows, the way people get richer is that someone comes up with a better way to do something, a way that takes a little less work.

GOLDSTEIN: Over time there are small improvements in life and in light. The Romans figure out how to make a lamp that's a little more efficient. People start to use whale oil. This, of course, is very, very bad for whales. But whales have a lot of fat. They were like these big swimming sources of fuel.

Still, even when you get all the way to the 1700s, life still looks more like ancient Babylon than the modern world. People still travel the same way - by foot, by horse, by sailing ship. Most people are still subsistence farmers, usually living in some kind of hut, trying to grow enough food not to starve to death.

KESTENBAUM: Year after year, there are tiny gains in productivity, little bits of economic growth, but not a lot. And light? Light still comes from finding stuff that's lying around and just lighting it on fire. Again, economist Bill Nordhaus.

NORDHAUS: You look at the picture of what happened here. It's economic history in a nutshell. From Babylonian times to around 1800, there were - even though there were improvements as best we can tell, they were very modest. And then around 1800 in the lighting, you can see it so clearly in lighting. It's just a enormous change in the pace of improvement.

KESTENBAUM: What happens in the 1800s is a few things. We start to really actively experiment. We try to discover stuff. And around 1850, a guy in Canada comes up with something that's not just a slightly-better wick or a slightly-more-efficient lamp. It is this magical liquid. With the right techniques, you can get it from coal or oil.

GOLDSTEIN: This big breakthrough? Kerosene. Not cutting edge now, but back then, Jane Brox says, kerosene was a huge deal.

BROX: When the first kerosene lamps came out, it was - as one historian said, it was the kind of oil people had dreamed about for centuries.

GOLDSTEIN: It was brighter. It was cleaner. And, importantly, it was much cheaper.

NORDHAUS: You work a day, you get about an hour of whale oil. Kerosene, you get about five hours.

KESTENBAUM: Whoa.

NORDHAUS: So it's about five times more efficient. Kerosene lit the world and saved the whales.

GOLDSTEIN: So if kerosene was so great, why did it take the world so long to find it? Science. This idea of professional scientists, this idea that there are lots of people who go to work every day at universities and do experiments, in the 1800s this is still a new thing.

KESTENBAUM: If you happen to be president of Yale University, this is around the time when you're thinking, you know, maybe we should get one of those science departments.

NORDHAUS: Why weren't they doing those experiments a century earlier? Well, Yale didn't have scientists a century earlier. They were teaching Greek and they were teaching logic.

KESTENBAUM: Now all these scientists are working on better ways to make light. And light is getting cheaper, more people are using it. No more locking yourself in and huddling in the dark all night. Around this time, street lights start popping up and people start going out at night.

GOLDSTEIN: So we have kerosene. What's the next big advance after that?

NORDHAUS: OK. Next big advance after that is the electric lamp.

GOLDSTEIN: The big one?

NORDHAUS: Well, you might think so.

GOLDSTEIN: You know, Jacob, I thought I knew the story of the lightbulb. You know, Thomas Edison, the great inventor. A story about science and innovation, you know, Edison's trying all these different filaments, these different designs and finally getting one that'll glow for hours.

But this eureka-lightbulb moment, it is not - it's not enough to get you to the world of really cheap light. Because Edison needed this other thing - he needed money. He needed lots and lots of money. Why? Because you can't light a light bulb without electricity. He needed to build a power plant.

PAUL ISRAEL: So right now we're at the location of the original power plant in Lower Manhattan.

GOLDSTEIN: This is Paul Israel. He's an Edison scholar. We met him here in New York City. And we're standing in front of this plaque. It says Thomas Alva Edison in big letters. And there's this picture, an etching.

ISRAEL: And the image that they show is the generator room of the power plant.

KESTENBAUM: With a bunch of guys in really long mustaches and hats?

ISRAEL: Right. This is 1882, so lots of mustaches at that point.

KESTENBAUM: The money part of building the power plant is so important that when they finally get this historic thing completed in 1882 - they get the power plant built and they're ready to turn it on - Edison is not here. He's a few blocks away at a big impressive stone building, where today there is another plaque to a guy who may have heard of - J.P. Morgan. It reads - the capitalist's capitalist, known throughout the world of finance, sought out by presidents, helped bankroll the industrialization of America. Can't write that on too many people's plaques. J.P. Morgan's bank and a bunch of investors, they put up the money for the power plant.

GOLDSTEIN: To be clear, they built this great big, expensive, complicated power station, the first central power station in the world - right? - basically inventing electric light. And when they turn it on, Edison is not there.

ISRAEL: Right. He was where he needed to be, with the people who had funded the whole thing, right? So at 3 p.m. on September 4, Edison flicked on the switch here at J.P. Morgan's office.

GOLDSTEIN: And what happened?

ISRAEL: It went on, and - as did lights all over the district. About a square mile of Lower Manhattan suddenly was lit by electricity.

KESTENBAUM: You think of Edison the inventor, but even more important is Edison the businessman. At the time, buildings in Lower Manhattan were running off gaslights. And Edison knew that was who he had to beat.

So he spent a lot of time thinking about economics?

ISRAEL: Yeah, well, he did, yeah. In fact, if you look at his notebooks, constantly he's going through and comparing the cost of what he's doing to what the cost of a gas system is.

KESTENBAUM: (Laughter) You never think about that.

ISRAEL: Well, and that's what made him such a good innovator, right? Because he recognized that these economic questions were just as important in designing what he did in the laboratory.

KESTENBAUM: When you think of economic growth, how much do you think of it is coming from, like, individual, like, eureka moments and inventions and stuff like that? And how much is it the stuff around it, like, the ability to finance these things, the economic structure around it?

ISRAEL: So most of it is actually the structure around it.

GOLDSTEIN: To light a square mile of Lower Manhattan, Edison needed a whole financial system. He needed patents, a way to protect his ideas so no one would steal them. He needed a company, a way a bunch of different investors could come together and risk money - a lot of money - to build a power plant and lay wires so you could try this crazy thing - light without fire. Edison comes along at a time when all this machinery, patents, corporations, banks is in place.

KESTENBAUM: There were consequences to growth. I mean, those first power plants burned coal. And pollution was pretty bad. Edison built a huge power plant on the East Side of Manhattan. And at some point the city health department got involved. And this is according to The New York Times, quote, "when it was found Health Department men were trying to photograph the smokestacks, scouts were put on the company's roof who ordered the feeding of coal stopped whenever photographers appeared." On the other hand, you know how the city lit up with cheap electric light? Tradeoffs.

GOLDSTEIN: Around this time, everything is getting faster and cheaper. Scientists keep making new discoveries. You get the internal combustion engine, the tractor. For the first time in human history, most people don't have to work as farmers.

KESTENBAUM: This went on decade after decade all through the 20th century. All kinds of things got much cheaper, like light.

GOLDSTEIN: And if you look at the really long arc here, it's amazing. I mean, go all the way back to the Babylonians. OK. Babylonians, you worked all day. You got the equivalent of 10 minutes - 10 minutes of light.

KESTENBAUM: Four thousand years later in the 19th century with kerosene lamps, things are better. A day's labor gets you five hours of light.

GOLDSTEIN: And by the time Nordhaus does his light study in the 1990s, if you work a day, how much light do you get?

NORDHAUS: Maybe 20,000.

KESTENBAUM: Twenty-thousand hours?

NORDHAUS: Twenty-thousand hours, yeah.

KESTENBAUM: (Laughter).

NORDHAUS: I mean, you basically - you have your house lit up. You have your streets lit up. You have your - all your equipment on. You have your air conditioner on. You have all the stuff you're doing is - you're saturated with light. The main thing is you're saturated with light.

GOLDSTEIN: Economic growth isn't all good. There's pollution, there are environmental consequences. But fundamentally, growth is about things getting faster, getting cheaper, getting more efficient. It's about doing the same amount of work and being able to buy 20,000 hours of light instead of 10 minutes. And as a result, it's about being able to work less, or to buy other stuff that used to be just for the wealthy. We can buy books. We can take vacations.

KESTENBAUM: Even today, there are still people who go to work every day and try to figure out how to make a better light bulb.

JOHN EDMOND: This morning I went to the bulb factory for about an hour.

GOLDSTEIN: This is John Edmond. He's one of the founders of a company called Cree. They make LED light bulbs, which of course are much more efficient than regular bulbs.

EDMOND: You'll make - you'll try an experiment and you'll say, holy crap, we just got more light out of this thing by using this contact material or flipping the chip over.

KESTENBAUM: Jacob, when we talk about economic growth every year, you know, when we say the economy grew a couple percent, that happens because every day out there, someone somewhere in some corner of the economy has figured out how to do something a little bit better or a little bit faster or a little less expensively. And this process has gone on year after year for hundreds of years now.

And one question I always have when I think about this is, like - and not just with light - but this whole story of constant economic growth, constant productivity improvement. My question is, is it going to go on forever or at some point we're going to run out of ways to make things better?

EDMOND: We might double from where we are now. But we're not going to be triple and quadrupling it because there are physical limits. I mean, will a car go a a million miles an hour? No.

(LAUGHTER)

EDMOND: It just won't. It just - it's not going to happen.

KESTENBAUM: For the light bulb at least, John says, we may actually be near the end.

(SOUNDBITE OF MUSIC)

GOLDSTEIN: This show originally aired in 2014. You can email us at p..y@npr.org or you can find us on Facebook or Twitter. Today's show was originally produced by Caitlin Kenney and Damiano Marchetti (ph). The rerun was produced by Sally Helm.

Response:

1. It's difficult to talk about the long run impact of growth over generations (and indeed civilizations) because it is difficult to compare prices across that much time. What is the measure that Professor Nordhaus used to overcome this difficulty?

2. We cannot dispute the importance of the light bulb that Edison invented, but one point raised in this podcast is that it takes a whole financial and economic infrastructure to implement such a bold and radical change. With that in mind, explain the statement that "finance built the power plant that made electric lights possible."

3. This story is just one example of how things get more efficient and less expensive over time. In this section I want you to pick a technologyand profile it's evolution over the years (e.g. power,communication, travel). Explain how innovations in this technology have benefited society and helped us make use of our scarce resources.