官 includes both civil and military officials. Tu Mu enumerates the following classes as likely to do good service in this respect: “Worthy men who have been degraded from office, criminals who have undergone punishment; also, favourite concubines who are greedy for gold, men who are aggrieved at being in subordinate positions, or who have been passed over in the distribution of posts, others who are anxious that their side should be defeated in order that they may have a chance of displaying their ability and talents, fickle turncoats who always want to have a foot in each boat (飜覆變詐常持兩端之心者). Officials of these several kinds,” he continues, “should be secretly approached and bound to one’s interests by means of rich presents. In this way you will be able to find out the state of affairs in the enemy’s country, ascertain the plans that are being formed against you, and moreover disturb the harmony and create a breach between the sovereign and his ministers.” The necessity for extreme caution, however, in dealing with “inward spies,” appears from an historical incident related by Ho Shih: “羅尙 Lo Shang, Governor of 益州 I-chou, sent his general 隗伯 Wei Po to attack the rebel 李雄 Li Hsiung of 蜀 Shu in his stronghold at 郫 P‘i. After each side had experienced a number of victories and defeats, Li Hsiung had recourse to the services of a certain 朴泰 P‘o-t‘ai, a native of 武都 Wu-tu. He began by having him whipped until the blood came, and then sent him off to Lo Shang, whom he was to delude by offering to co-operate with him from inside the city, and to give a fire signal at the right moment for making a general assault. Lo Shang, confiding in these promises, marched out all his best troops, and placed Wei Po and others at their head with orders to attack at P‘o-t‘ai’s bidding. Meanwhile, Li Hsiung’s general, 李驤 Li Hsiang, had prepared an ambuscade on their line of march; and P‘o-t‘ai, having reared long scaling-ladders against the city walls, now lighted the beacon-fire. Wei Po’s men raced up on seeing the signal and began climbing the ladders as fast as they could, while others were drawn up by ropes lowered from above. More than a hundred of Lo Shang’s soldiers entered the city in this way, every one of whom was forthwith beheaded. Li Hsiung then charged with all his forces, both inside and outside the city, and routed the enemy completely.” [This happened in 303 A.D. I do not know where Ho Shih got the story from. It is not given in the biography of Li Hsiung or that of his father Li 特 T‘ê, _Chin Shu_, ch. 120, 121.] 11. 反間者因其敵間而用之 Having _converted spies_, getting hold of the enemy’s spies and using them for our own purposes.