Mo Zi was a philosopher of ancient China in the fifth Century. He was also a strategist and engineer.

Another engineer, Gongshu Ban has invented a special ladder that was about to be put to use in a war against the small State of Lu by the King of a stronger state, Chu. It would be easier to take a city with the help of the ladder, because soldiers could climb over the city wall instead of a direct attack to the fortified city gate. When Mo Zi got the wind of the war, he hurried ten days and nights to the State of Chu to see Gongshu Ban in the hope that he could prevent the war.

"A man has insulted me, I want to kill him with your help. I can give you a handsome payment." He asked Gongshu Ban.

"I'm a man of honor. I won't kill people just for money." Was the answer. 

"Chu is a strong state with a large population and vast land. Yet you are helping it to attack the weak state of Lu. You say you don't kill people, do you know how many people will die in the war because of your new invention? Is there any difference between that and you take their lives with your own hands?" he quested.

Gongshu Ban lost in words. He could only say the war was the idea of the King of Chu. So the two went to see the King.
"Your Majesty, can I ask a question Please? A man has a gorgeous carriage yet he steals the ramshackle carriage from his neighbor. He's got numerous gorgeous clothes yet he steals his poor neighbour's shabby suit. What kind of man you think he is?" Mo Zi asked the King.

"He must be a born thief." The King giggled.

"Your Majesty, Chu is a strong state rich in land and produce. The state of Lu is a small poor state. Now Chu will attack Lu. Don't you think the action is somewhat just like the rich man's behavior?" Mo Zi followed up his question.

"Well said. Still, I will carry out the war against Lu because Gongshu Ban has already invented the ladder for me." The King said arrogantly.

"Having the ladder will not necessarily guarantee a success for you in the war. I could simulate the war before your Majesty." Mo Zi suggested.

They brought their tools, pretending to be city wall, the ladder, attacking and defense weapons that was supposed to be needed in a war.

Gongshu Ban tried several attacking measures and strategies but every time his attacks were blocked by Mo Zi.

At last, Gongshu Ban looked at Mo Zi and said: "I've got another way to overcome you. I just won't tell." "I know it. I won't tell either." Was the words from Mo Zi.

That confused the King, who asked for an explanation. Mo Zi said: "He meant to kill me. But I've told my disciples the way of defense. So there's no help to the war even if you kill me."

The King of Chu finally gave up his planned attack to Lu.