How to Read “Burn ten mon worth of oil to do five mon worth of night work”
Jūmon ga abura wo toboshite gomon no yonabe seyo
Meaning of “Burn ten mon worth of oil to do five mon worth of night work”
This proverb teaches that you should work efficiently, even if it costs a little money, to ultimately gain more profit.
On the surface, it might sound negative. It seems to say that working at night isn’t worth it if you spend ten mon on oil but only earn five mon.
However, the true meaning is actually the opposite. It’s a positive lesson about smart investment.
The proverb warns against being penny-wise and pound-foolish. Instead of continuing inefficient work to save small expenses, you should invest appropriately to increase productivity and earn greater profits.
This saying applies when you need to balance cost-cutting with efficiency. For example, it’s better to pay for good lighting and work efficiently than to save on electricity and work slowly in the dark.
In modern times, this proverb reminds us not to skimp on necessary equipment or employee training. Think long-term about profits, not just immediate expenses.
Origin and Etymology
The exact origin of this proverb isn’t clearly documented. However, its structure reflects the daily life of common people during the Edo period.
Notice the specific amounts mentioned: “ten mon” and “five mon.” During the Edo period, the mon was the most familiar currency unit for ordinary people.
Ten mon could buy you tofu. Five mon could get you some cheap sweets. These were everyday amounts that regular people understood well.
This suggests the proverb came from the economic sensibilities of common folk, not wealthy merchants or scholars.
“Burning oil” refers to the cost of lighting at night. In the Edo period, lamp oil made from rapeseed was quite expensive.
Most people simply sat in darkness after sunset. Deciding whether to spend money on oil for night work was a serious economic choice.
The proverb presents a calculation: if you spend ten mon on oil but only accomplish five mon worth of work, it makes no sense.
But it also implies the opposite logic. If spending ten mon can earn you fifteen mon or more, you should invest without hesitation.
This reflects the rational, merchant-minded thinking that spread among common people as commerce developed during the Edo period. It shows how cost-benefit analysis became part of everyday wisdom.
Interesting Facts
The price of lamp oil in the Edo period varied greatly by season and region. Winter demand was especially high, sometimes doubling the summer price.
Merchants had to recalculate whether night work was profitable each season. This constant calculation helped develop the rational spirit of Edo merchants.
The word “yonabe” (night work) originally came from “yonabe” (night pot), referring to keeping a fire going late at night for work.
Not just seamstresses did night work. Blacksmiths, dyers, and other craftsmen also worked through the night during busy seasons.
Usage Examples
- I hesitated to invest in new software, but it was the opposite of “Burn ten mon worth of oil to do five mon worth of night work”—I ended up wasting time and losing money
- Don’t keep using that old air conditioner just to save energy. Like “Burn ten mon worth of oil to do five mon worth of night work” teaches us, buying a new one will reduce electricity costs and improve work efficiency
Universal Wisdom
This proverb reveals a fundamental human conflict. We struggle between two opposing desires: avoiding immediate losses and gaining long-term benefits.
Everyone feels pain when money leaves their hands. Ten mon for oil is money that definitely goes out. But the income from night work is uncertain.
You might not earn as much as you hoped. This fear of uncertainty makes people hesitate, even when investment is necessary.
Our ancestors understood this psychological trap. Fearing immediate expenses can lead to even bigger opportunity losses.
Working with needles in darkness takes longer, produces lower quality, and ultimately damages your reputation. Being cheap and being wisely frugal are completely different things.
The deep wisdom here is that common people understood the concept of “investment.” Money isn’t just something that disappears when you spend it.
When used properly, money comes back multiplied. This shift in thinking opens the door from stagnation to growth.
Humans instinctively avoid risk. But only by taking calculated risks can we create a better future.
Our ancestors learned this universal truth from daily experience and passed it down to us.
When AI Hears This
Burning oil is thermodynamically a one-way process. Ten mon worth of oil combusts into light and heat and can never return to oil.
This is entropy increase—the law that usable energy always decreases. What’s interesting is that the ten mon lost and the five mon earned are completely different types of value.
Oil combustion loses chemical energy itself, which is completely consumed and irreversible. But the five mon earned from labor is money that can accumulate.
This proverb compares two different time scales: the one-way flow of increasing entropy and the circular, accumulating economic system.
Physical laws always involve loss, yet this proverb points out the contradiction of deliberately choosing an economic transaction with a net negative return.
Thinking deeper, human labor itself also involves entropy increase. Night work depletes physical energy, which you replenish with food.
Energy always dissipates as heat in this process. So it’s not just the ten mon of oil—the human body as a “biological engine” is also burning fuel.
What this proverb truly warns against is double entropy increase. Both oil and human body suffer irreversible losses, while the value gained is only half.
This is fundamentally inefficient.
Lessons for Today
This proverb teaches you “the difference between smart frugality and foolish cheapness.” Saving money is a virtue, but cutting everything isn’t the answer.
What matters is developing judgment about what deserves spending and what should be cut.
Do you skip health checkups to save money, only to let illnesses worsen? Do you refuse to buy books for skill development, missing growth opportunities?
That’s like refusing to spend ten mon on oil and ending up unable to create even five mon of value.
On the other hand, invest courageously in things that truly produce results. Good tools, comfortable environments, quality learning—these reliably increase your productivity and bring greater returns.
In modern society, time is the most precious resource. When you can buy time with money, invest without hesitation.
Dishwashers, robot vacuums, taxi fares—these aren’t mere luxuries. They’re investments that protect your time.
With that saved time, you can do more valuable things. Don’t be distracted by immediate expenses. Judge with a long-term perspective.
That’s the wisdom this proverb teaches for living richly.
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