When a person dies, the knowledge that has been passed down is also lost.

Arjuna's concern is not only about the loss of lives due to war. He believes that if elders and those who know the traditions disappear, the customs and knowledge that have maintained the standards of the family will no longer be passed on to the next generation.

Here, the term "tradition" is explained not as a mere old form, but as a mechanism that connects individuals to families and society, and supports them in staying on the right path. If this restraint is lost, families and societies will lose control, and immorality will spread. Arjuna's discussion expands from individual sorrow to the collapse of social order that lasts for a long time after the war.

Japanese Translation from the Geeta Press Edition - Chapter 1, Section 40: "The Traditions of a Clan are Lost"

When the family name perishes, the eternal duties of the family are destroyed. When dharma is lost, the entire family is ruined; a man who is not righteous will surely be ruined. || 40 ||

Vocabulary

"kulakṣaye" means "when a family or clan is destroyed."

"praṇaśyanti" means "to be extinguished."

"kuladharmāḥ" means "family traditions" and "the laws of a clan."

"sanātanaḥ" means "eternal" or "ancient."

"dharme naste" means "when dharma, righteous order, is lost."

"kulam kṛtsnam" means "the entire clan."

"adharmaḥ abhibhavati" means "unrighteousness prevails."

Translation

"When a family is destroyed, the traditions of the house that have continued since ancient times disappear."

And when virtue is lost, impropriety comes to dominate the entire family.”

Annotated Translation

A good house has many good, useful customs and traditions accumulated within it.

They are passed down from generation to generation, maintaining a high standard of conduct for the family, and helping both men and women stay on the right path.

These beneficial and improving habits and customs are called "family traditions" in a single word.

When a family declines, the elderly people who know those customs and traditions disappear.

Then, it is natural that the remaining women and children lose this knowledge, and in such a way, traditions disappear and are lost.

There are five motivations that keep people on the path of virtue and prevent them from committing sins.

Fear of God.

The commandments of the Holy Scripture.

The fear of breaking family traditions.

National laws.

It is a fear of physical harm or financial loss.

Among these, God absolutely exists, and the commandments in scriptures represent truth, but they depend on a person's faith, and are not directly visible motivations.

The laws of a nation only govern the citizens of that nation. However, those who hold power generally do not respect it.

The fear of physical harm or financial loss, in many cases, affects only individuals.

Only the traditions of a family can connect an individual to both the family and society.

Societies and families that have lost beneficial habits and traditions are like wild horses without reins, becoming chaotic and self-indulgent.

A strong-willed person, no matter how beneficial a law may be, will not try to comply with it.

When society and its members abandon all restraints, crime naturally expands its influence within that society and family.

This means that, "sin dominates the entire family."