Burst into an angry roar at the sight of injustice and draw your sword to help the victim. This is an old Chinese saying, calling on people to fight crime without the slightest hesitation. People who believe in it have a very strong sense of justice. The very sight of someone trying to commit a crime - attempt to rob, rape or pilfer - or an act of bullying swings them into action. They descend on criminals like a curse. A common feature of such heroes is that they act on impulse, without thinking about potential dangers.

This heroic act is called zhengyi chongdong - literally "justice-induced impulse". Generally, an impulse is something a sensible person should try to avoid because it could force him to commit a rash act or create an uncontrollable situation. Zhengyi chongdong, however, is a valuable, and commendable, human trait, and three recent happenings illustrate this.

The day before yesterday, Cai Changlu, a 63-year-old resident of Chongqing municipality, was walking past a warehouse in Shunde, Guangdong province, on his way to visit relatives when he saw several men armed with swords stealing washing machines from a vehicle. The old man rushed to stop the minivan the robbers were escaping in with the loot. But instead of stopping, the robbers accelerated the speed of the minivan and ran over him before fleeing.

On Dec 31, 2009, Yang Jiyuan, a student from the Zhejiang Industry University, was stabbed to death when he and his classmates tried to stop four persons from stealing passers-by in front of the university in Hangzhou.

Twelve days earlier in the same city, two persons riding a motorcycle snatched a woman's handbag. A young man coming from the opposite side got down from his bicycle, and used it to knock down the culprits from their motorbike. Other passers-by ran to his help immediately. But after the criminals were nabbed, he picked up his deformed bicycle and simply walked away. The identity of the hero remains unknown.

All three men acted on "justice-induced impulse". They didn't think before jumping into dangerous situations to prevent a crime, with two of them paying the ultimate price for the courage of their conviction.

Some people may question the rationality of their actions, saying the things they saved or tried to save were not worth their lives. I think their actions are worthy of the highest honor, because what they helped save is not merely stolen goods but a virtue that is being abandoned by more and more people today.

There have been hundreds of reports of ruffians robbing passengers or raping a woman in long-distance buses while the rest of the passengers remain silent spectators and passers-by turning a blind eye to crimes. Such cases show people have lost their zhengyi chongdong.

But there are reasons why many people no longer act on zhengyi chongdong. The first is society's new concept about "the value of human life". After decades of encouraging people to "be brave in fighting evil", recent years have seen the promotion of the notion: "Human life is the most valuable thing in the world."

Such an understanding, however, is going too far. For many people, nothing in this world is worth sacrificing his/her life for. Certainly, one should not blame these people for their inaction. After all, everybody has the right to treasure his/her life. But it is a pity to see zhengyi chongdong become a rare trait.

Another reason why so few people act on "justice-induced impulse" is that families of people who have died or been seriously injured while trying to save someone or prevent a crime have not been compensated properly. Such families may have enjoyed the spotlight for a brief while, but have suffered immensely after losing their main bread earner.

A typical example of this is Wei Zhaoan, who jumped from a 19-story building to his death in 2005 because he could not afford the heavy medical fees for treatment after he was stabbed by a thief he tried to nab in Zhuhai, Guangdong province, two years earlier.

The Zhuhai government had awarded him 10,000 yuan for his bravery, but that sum was far from enough to restore Wei and his family's life to normal.

E-mail: liushinan@chinadaily.com.cn