How to Read “The sun and moon have no private illumination”
Jitsugetsu ni shishō nashi
Meaning of “The sun and moon have no private illumination”
“The sun and moon have no private illumination” means that just as the sun and moon shine equally on all people without discrimination, we should treat others fairly without personal feelings or favoritism.
This proverb is especially used to describe the proper mindset for people in positions of authority or leadership.
It teaches that teachers with students, bosses with employees, and parents with children should not change their attitudes based on personal likes or dislikes.
By using the sun and moon as examples—celestial bodies everyone knows—this saying helps people intuitively understand what fairness means.
Even in modern society, this spirit is required of organizational leaders and people in public positions.
This proverb contains deep insight by comparing the importance of being just to all people—without being swayed by personal preferences or interests—to a universal phenomenon in nature.
Origin and Etymology
The exact origin of this proverb in historical texts has not been clearly identified.
However, it is believed to be influenced by classical Chinese thought, particularly the Confucian worldview that explains the fairness of heaven.
“Jitsugetsu” refers to the sun and moon. Since ancient times in East Asian cultures, the movement of celestial bodies has symbolized the most just and unwavering things.
The sun rises every day, and the moon waxes and wanes, but they never shine only on specific people or avoid anyone.
In “shishō,” the character “shi” does not mean “I” in modern Japanese. In classical language, it means “personal feelings” or “favoritism.”
Therefore, “shishō nashi” means “there is no illumination based on personal feelings.”
This expression was likely often used when explaining the ideal attitude of rulers and leaders.
In Japan, this type of expression appears in educational texts from the Edo period.
Records show it was used in contexts explaining samurai ethics and merchant morality.
This phrase, which presents heaven’s fairness as a standard for human society, may have been an important concept that paradoxically expressed the ideal of equality during an era of strict social hierarchy.
Usage Examples
- The principal treats all students equally with the spirit of “The sun and moon have no private illumination”
- Judges are in a profession where the fairness of “The sun and moon have no private illumination” is required above all else
Universal Wisdom
The proverb “The sun and moon have no private illumination” reveals two truths: humanity’s inherent “sensitivity to unfairness” and simultaneously “the difficulty of being fair.”
Everyone is remarkably sensitive when they are treated unfairly.
Even if you don’t notice when you’re on the favored side, the moment you’re on the receiving end of poor treatment, you feel that unfairness keenly.
This sense is a fundamental human trait that even young children possess.
This is why being fair has been valued throughout history and across cultures as the foundation of human society.
At the same time, being completely fair is extremely difficult for humans.
We are emotional beings with likes and dislikes, influenced by past experiences, and sometimes our judgment becomes dull when we’re tired.
Even without consciously trying to discriminate, differences in attitude can emerge unconsciously.
This is precisely why our ancestors invoked the sun and moon as absolute entities.
Because it’s difficult for humans, they needed to hold up the unwavering fairness of celestial bodies as an ideal.
This proverb teaches the importance of maintaining high ideals while acknowledging human weakness.
When AI Hears This
The light of the sun and moon reaches everyone equally. This quality of “not playing favorites” is a surprisingly rational strategy from an information theory perspective.
When a sender selects only specific recipients for information, a cost is incurred each time to judge “who to send to.”
For example, if the sun had to discriminate—”this person is good so brighter, this person is bad so darker”—it would need to continuously judge the good and evil of all 7 billion people on Earth every second.
The amount of information processing required for this judgment would be astronomical.
In other words, the act of selection itself generates enormous entropy, or disorder and uncertainty.
On the other hand, a broadcast method that sends light equally to everything has zero judgment cost.
No matter how many receivers there are, the burden on the sender doesn’t change.
In information theory, this is called “maximizing channel capacity.”
Because there’s no selection, the efficiency of the entire system becomes optimal.
Nature, without possessing computers, has adopted the most energy-efficient method of information transmission.
Fairness, before being a moral issue, was actually the most waste-free physical law.
Lessons for Today
What this proverb teaches modern people is the “responsibility of fairness” required by one’s position and role.
In daily life, we are all in positions where we influence others to some degree.
As parents, as seniors, as team leaders, or simply within friend groups.
At such times, it’s worth reflecting on whether we’re changing our attitudes based on our preferences or moods.
Especially in modern society, “fairness” is questioned in more situations than ever before.
These include social media posts and evaluations, and decisions about hiring and promotions.
In an era when unconscious bias is being made visible and problematized, the teaching of this old proverb takes on fresh meaning.
A practical tip is to take “one breath” before making decisions.
Before evaluating someone or making a judgment, ask yourself: “If the other person were different, would I make the same decision?”
While perfect fairness is difficult, you can maintain an attitude of striving for it.
Even if you can’t be as perfect as the sun and moon, your attitude of aiming for that ideal gives those around you a sense of security and trust.
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