In 500 B.C.（the 10th year of Dinggong，Duke of the state of Lu），Confucius was promoted to be the minister of the state of Lu mainly responsible for building，engineering，and later for legal construction.The state of Qi suggested a reconciliatory meeting with the state of Lu.Dinggong，Duke of Lu and Jinggong，Duke of Qi met at Jiagu（south of the present city of Laiwu，Shandong Province）.As Minister of Justice of the state of Lu，Confucius made a suggestion to Dinggong，and he held that "polite letters and martial arts always to together".