The original text has 軍行, but 旁 has been generally adopted as
yielding much better sense.
there should be any hilly country,
險阻 is 邱阜之地, according to Chang Yü.
ponds surrounded by aquatic grass, hollow basins filled with reeds,
The original text omits 蔣 and 生, so that 潢 and 井 join to make a
pair: “ponds and basins.” This is plausible enough at first sight,
but there are several objections to the reading: (1) 蔣 is unlikely
to have got into the text as a gloss on 潢; (2) it is easy to
suppose, on the other hand, that 蔣 and afterwards 生 (to restore
the balance of the sentence) were omitted by a copyist who jumped
to the conclusion that 潢 and 井 must go together; (3) the sense,
when one comes to consider it, actually requires 蔣, for it is
absurd to talk of pools and ponds as in themselves suitable places
for an ambush; (4) Li Ching (571–649 A. D.) in his 兵法 “Art
of War” has the words: 蔣潢蘙薈則必索其伏. This is evidently a
reminiscence of Sun Tzŭ, so there can be little doubt that 蔣 stood
in the text at this early date. It may be added that the _T‘ung
Tien_ and _Yü Lan_ both have 蔣, and the latter also reads 并 for 井.
or woods with thick undergrowth,
I read 小林 with the _Yü Lan_ in preference to 山林, given in the
original text, which is accepted by the commentators without
question. The text of the _T‘u Shu_ up to this point runs as
follows: 潢井蒹葭林木蘙薈者.
they must be carefully routed out and searched; for these are places
where men in ambush or insidious spies are likely to be lurking.
The original text omits 藏, which has been restored from the _T‘ung
Tien_ and _Yü Lan_. The _T‘u Shu_ omits 處 as well, making 所 a
substantive. On 姦 Chang Yü has the note: 又慮姦細潛隱覘我虛實聽我號令
伏姦當爲兩事 “We must also be on our guard against traitors who may
lie in close covert, secretly spying out our weaknesses and
overhearing our instructions. _Fu_ and _chien_ are to be taken
separately.”