Besides reduced working hours and the spread of labor-saving household appliances, what other factors in the process of modernization gave humans more leisure time?
The Enlightenment of the Present also mentions a factor we very easily overlook—light.
In a natural state, we spend half our time immersed in darkness. But artificial light lets us read and move around at night, and modern nightlife is built entirely on humanity’s ability to obtain artificial light cheaply.
The economist William Nordhaus regarded the plunge in the price of artificial light (and the resulting surge in its availability) as an important symbol of progress.
Since the Middle Ages, the inflation-adjusted price of 1 million lumen-hours (roughly the amount of light needed to read under a lamp for two and a half hours a day over a year) has fallen 12,000-fold: from about £35,500 in 1300 AD to less than £3 today.
People in ancient times worked at sunrise and went to bed at sunset not because, as some nostalgic romantics imagine, they revered a natural way of life, but because they simply couldn’t afford lighting at night.
Nearly all those bright, well-lit nighttime interiors in Chinese period dramas are lies. In ancient times, lighting an indoor space to that degree would have bankrupted even the emperor.
What’s more, looking only at the plunge in the cash price of artificial light actually underestimates the real progress behind it, because, as Adam Smith pointed out: “The real price of everything … is the toil and trouble of acquiring it.”
Nordhaus estimated how many hours a person had to work in different historical periods to earn enough for one hour of reading light at night.
A Babylonian in 1750 BC had to work fifty hours to earn enough to read cuneiform for an hour by the light of a sesame-oil lamp;
In 1800, a Briton had to labor for six hours just to keep a tallow candle burning for one hour;
By 1880, you needed to work 15 minutes to keep a kerosene lamp lit for an hour;
in 1950, eight seconds of earnings were enough to run an incandescent bulb for an hour;
In 1994, half a second of work could buy an hour of light from an energy-saving fluorescent lamp—in two centuries, the labor cost of lighting fell 43,000-fold.
And this progress still isn’t over: Nordhaus made this estimate before LED bulbs flooded the market, and in the not-too-distant future, cheap solar-powered LED lamps will transform the lives of more than a billion people who still don’t have electric lights.
Notes
- This article from the “New Psychology Knowledge Short Course” series was a short popular-science essay/ramble written at the time to accompany the related content of Zhichao Wei: New Psychology Knowledge Course. It was published on the now-shut-down platform Fantuan, and the original link no longer exists.
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