Part 66

It is through the information brought by the converted spy that we are able to acquire and employ local and inward spies.

Tu Yu expands 因是而知之 into 因反敵間而知敵情 “through conversion of the enemy’s spies we learn the enemy’s condition.” And Chang Yü says: 因是反間知彼鄉人之貪利者官人之有隙者誘而使之 “We must tempt the converted spy into our service, because it is he that knows which of the local inhabitants are greedy of gain, and which of the officials are open to corruption.” In the T‘ung Tien, 鄉 has been altered to 因, doubtless for the sake of uniformity with § 9.

23. 因是而知之故死間爲誑事可使告敵

It is owing to his information, again, that we can cause the doomed spy to carry false tidings to the enemy.

“Because the converted spy knows how the enemy can best be deceived” (Chang Yü). The T‘ung Tien text, followed by the Yü Lan, has here the obviously interpolated sentence 因是可得而攻也.

24. 因是而知之故生間有使如期

Lastly, it is by his information that the surviving spy can be used on appointed occasions.

Capt. Calthrop omits this sentence.

25. 五間之事主必知之知之必在於反間故反間不可不厚也

The end and aim of spying in all its five varieties is knowledge of the enemy;

I have ventured to differ in this place from those commentators—Tu Yu and Chang Yü—who understand 主 as 人主, and make 五間之事 the antecedent of 之 (the others ignoring the point altogether). It is plausible enough that Sun Tzŭ should require the ruler to be familiar with the methods of spying (though one would rather expect 將 “general” in place of 主). But this involves taking 知之 here in quite a different way from the 知之 immediately following, as also from those in the previous sentences. 之 there refers vaguely to the enemy or the enemy’s condition, and in order to retain the same meaning here, I make 主 a verb, governed by 五間之事. Cf. XI. § 19, where 主 is used in exactly the same manner. The sole objection that I can see in the way of this interpretation is the fact that the 死間, or fourth variety of spy, does not add to our knowledge of the enemy, but only misinforms the enemy about us. This would be, however, but a trivial oversight on Sun Tzŭ’s part, inasmuch as the “doomed spy” is in the strictest sense not to be reckoned as a spy at all. Capt. Calthrop, it is hardly necessary to remark, slurs over the whole difficulty.

and this knowledge can only be derived, in the first instance, from the converted spy.

As explained in §§ 22–24. He not only brings information himself, but makes it possible to use the other kinds of spy to advantage.

Hence it is essential that the converted spy be treated with the utmost liberality.

26. 昔殷之興也伊摯在夏周之興也呂牙在殷

Of old, the rise of the Yin dynasty

Sun Tzŭ means the 商 Shang dynasty, founded in 1766 B.C. Its name was changed to Yin by 盤庚 P‘an Kêng in 1401.

was due to I Chih

Better known as 伊尹 I Yin, the famous general and statesman who took part in Ch‘êng T‘ang’s campaign against 桀癸 Chieh Kuei.

who had served under the Hsia. Likewise, the rise of the Chou dynasty was due to Lü Ya

呂尙 Lü Shang, whose “style” was 子牙, rose to high office under the tyrant 紂辛 Chou Hsin, whom he afterwards helped to overthrow. Popularly known as 太公, a title bestowed on him by Wên Wang, he is said to have composed a treatise on war, erroneously identified with the 六韜.

who had served under the Yin.

There is less precision in the Chinese than I have thought it well to introduce into my translation, and the commentaries on the passage are by no means explicit. But, having regard to the context, we can hardly doubt that Sun Tzŭ is holding up I Chih and Lü Ya as illustrious examples of the converted spy, or something closely analogous. His suggestion is, that the Hsia and Yin dynasties were upset owing to the intimate knowledge of their weaknesses and shortcomings which these former ministers were able to impart to the other side. Mei Yao-ch‘ên appears to resent any such aspersion on these historic names: “I Yin and Lü Ya,” he says, “were not rebels against the Government (非叛於國也). Hsia could not employ the former, hence Yin employed him. Yin could not employ the latter, hence Chou employed him. Their great achievements were all for the good of the people.” Ho Shih is also indignant: 伊呂聖人之耦豈爲人間哉今孫子引之者言五間之用須上智之人如伊呂之才智者 可以用間葢重之之辭耳 “How should two divinely inspired men such as I and Lü have acted as common spies? Sun Tzŭ’s mention of them simply means that the proper use of the five classes of spies is a matter which requires men of the highest mental calibre like I and Lü, whose wisdom and capacity qualified them for the task. The above words only emphasise this point.” Ho Shih believes then that the two heroes are mentioned on account of their supposed skill in the use of spies. But this is very weak, as it leaves totally unexplained the significant words 在夏 and 在殷. Capt. Calthrop speaks, rather strangely, of “the province of Yin ... the country of Hsia ... the State of Chu ... the people of Shang.”

27. 故惟明君賢將能以上智爲間者必成大功此兵之要三軍之所恃而動也

Hence it is only the enlightened ruler and the wise general who will use the highest intelligence of the army for purposes of spying,

Ch‘ên Hao compares § 15: 非聖智不能用間. He points out that 湯武之聖 伊呂宜用 “the god-like wisdom of Ch‘êng T‘ang and Wu Wang led them to employ I Yin and Lü Shang.” The T‘u Shu omits 惟.

and thereby they achieve great results.

Tu Mu closes with a note of warning: 夫水所以能濟舟亦有因水而覆沒者間 所以能成功亦有憑間而傾敗者 “Just as water, which carries a boat from bank to bank, may also be the means of sinking it, so reliance on spies, while productive of great results, is oft-times the cause of utter destruction.”