In this article no in-depth explanation of Chinese characters, hardly references, just an interesting story. There is a fascinating link with hexagram 29 and a passage from the Mozi 墨子. The name of this hexagram, kan 坎, means 'pit, hole in the ground, trap'. But used doubled (kan-kan 坎坎) it is an onomatopoeia for the sound of drumming, as in the poem Fa Tan 伐檀 in The Book of Odes:

坎坎伐檀兮
Kan-kan go his blows on the sandal trees...

Often when a character is doubled it is a representation of a sound. We find this doubling in the third line of hexagram 29:

來之坎坎
The kan-kan of coming/approaching...

Something which produces a kan-kan sound is approaching.

The trigram Water is associated with danger, and with the ears, with listening. All these elements of

• pit
• sound of drumming
• danger
• listening

...can be found in a passage from the Mozi, which describes an alarm system to discover enemies who are approaching a city through underground tunnels. It can be found on p. 799 of Ian Johnston's translation.

Ralph Sawyer describes it like this:

Mo-tzu's counter-methods were premised upon intensively observing the enemy's activities from high lookout towers in order to detect any evidence of excavations, such as new earthen mounts or sudden turbidity in moat or river water. These visual efforts were to be supplemented with a virtual network of listening wells positioned every five paces around the wall's interior, excavated to a minimum depth of fifteen feet or three feet below the water line. Guards, whose task was facilitated by large earthen jars fashioned specifically for the purpose with thin leather membranes stretched over the mouths, were posted at the bottom to carefully listen for any indication of enemy tunneling. Once detected, these multiple wells would allow a fairly accurate determination of the tunnel's location preliminary to mounting countermeasures."
Fire and Water - The Art of Incendiary and Aquatic Warfare in China, p. 33

The drum in a pit, listening for approaching danger - it all fits the imagery of hexagram 29 pretty well. We can even find it in the text of hexagram 29:

Judgment text:
習坎.有孚.維心亨.行有尚.
Repeated kan. Inspire confidence. Protect the inner offering. To proceed is helpful.

The drums are sounding, meaning that enemies are approaching! The lord has to inspire confidence in his people and his army to defend the city. The central offering in the city has to be protected. Proceeding the enemy (as Mozi suggests) is helpful.

Line 1:
習坎.入于坎窞.凶.
Repeated kan enters the pit. Ominous.

The sound that the digging soldiers produce enters the pit through the drums. Danger is coming!

Line 2:
坎有險.(求小得.)
The pit has danger. (Seek small results.)

The sound the drums make signifies danger. (As an oracular omen this means only small results can be achieved.)

Line 3:
來之坎坎.險且枕.入于坎窞.勿用.
The kan-kan of approaching. Danger is more and more nearing. It enters the pit, which is of no use anymore.

The enemies are getting closer, and have reached the drum pits which are close to the city. (see for 'nearing' as a meaning of 枕 the 漢語大詞典, Vol. 4, p. 880). 

Line 4:
樽酒簋貳.用缶.納約自牖.(終無咎.)
Wine vessels and baskets cannot be trusted. Use earthenware. Cover its opening. (In the end no fault.) 

A description of the type of vessel to be used (I translate 納約 as 'to cover' because 納 can mean 'to wear' and  約 'to tie up') and what to do with it.

Line 5:
坎不盈.祇既平.(無咎.)
The kan-drum/pit is not full, the earth spirit is at peace. (No fault.)

The drums do not sound, so nothing is wrong.

I don't see how the sixth line can be linked with all this, and no doubt I am translating the texts in a direction which fits my purpose. Nevertheless I found it a very interesting connection which gives additional meaning & interpretation to hexagram 29 when you receive it as an answer from the Yi.

The Mythbusters have tested the Chinese invasion alarm in one of their episodes.

I was watching Transformers 2 with Irian (9), which has a scene where a library gets destroyed by a Decepticon Pretender.

Me:
"What a great loss of all those books!"

Irian:
"What a great loss of all that wisdom."

The Yi often talks about fu 孚, a character which is many times translated as 'trust', 'confidence' or 'truth'. But what is fu? With many hexagrams the Yi mentions that there is fu: 有孚. But where is it?

On bronze inscriptions we see 孚 mainly used as a verb: to capture people, chariots, or other materials during a battle (see the entries in 金文引得, 春秋戰國卷 on p. 100). It was the act of acquiring war booty, and sometimes it also referred to the booty itself. But it mainly was a verb. This meaning was lost in later centuries, instead of a verb it became a quality. The Shijing 詩經, The Book of Odes, contains a good example of fu as a quality:

王配于京、世德作求。
永言配命、成王之孚。

King [Wu] was their worthy successor in his capital,
Rousing himself to seek for the hereditary virtue,
Always striving to accord with the will [of Heaven] ;
And thus he secured the confidence due to a king.
Shijing M243

Here Fu is translated as ‘confidence’, but it is not the confidence of the king, it is the confidence that the king inspires in his people. That is the quality of fu: through sincerity you inspire confidence or trust in others, the others have confidence in you. Fu is a quality, just as de 德, ‘virtue’, is a quality. This quality is visible in the fifth line of hexagram 14:

厥孚交如威如吉
He inspires confidence which connects and creates reverence.

I’m reading jiao 交 as “兩者相接觸” (漢語大詞典-2.327) and wei 威 as “顯示的使人畏懼懾服的力量” (漢語大詞典-5.218). The quality of fu enables the king to connect with his people and make them stand in awe with respect and trust.

At the sixth line of hexagram 37 fu again is connected with wei, ‘creating awe/reverence’:

有孚威如
Having fu, (thereby) creating reverence.

At the fifth line of hexagram 51 there is again mention of a connection:

有孚攣如无咎
Having fu which joins together. No fault.

Reading luan 攣 as “牽繫不斷；連綴” (漢語大詞典-7.799).

At the fifth line of hexagram 58 the fu is severed:

孚于剝有厲
The fu is harmed, giving trouble.

Reading bo 剝 as “傷害” (漢語大詞典-2.713). If the king was not able to inspire confidence this surely would lead to trouble.

The link between fu in the old meaning of ‘capturing’ or ‘captive’ and the meaning of 'inspiring confidence in others' can be seen in the bronze inscriptions: these inscriptions often commemorated the captures that were made during a siege. The captures were trophies, which had to be recorded to inspire confidence in the current generation and the ones to come: the king was/had been a trustworthy and reliable leader.

So what does it mean when you read in the Yijing that there is fu? It depends on the situation, but it could indicate that there is sincerity (genuineness, naturalness, authenticity), which enables to connect with the goals that are set, or with the means that can be put to use. Without fu there is no connection and it will be very difficult (though not impossible) to achieve anything. Fu works on the long term, without fu you are only able to achieve limited goals on the short term. Fu enables you to get and keep processes going, it is the oil that keeps the motor running smoothly and avoids damage. If there is no fu in you or the person(s) involved, it is better to reconsider your plans and think about your motivations and intentions. Fu is a quality that is essential when you work with other people. Without it, cooperation can be pretty tough.

(The following article mainly serves as an exercise in showing the importance of the variant texts of the Yijing, loan characters and homonyms.)

Left: a tree ( lower part) cut down by an axe (upper part, left). Right: a knife. Derivation: peel a cut-down tree.
(De I Tjing voor de 21ste Eeuw, p. 175)

Alfred Huang says:

The ideograph of bo consists of two parts. The main part, on the right, is a picture of an ancient weapon, dao, a knife. The left part was originally the character bo, providing the sound. Later this character was replaced by lü, the name of King Wen's famous sword. Lü also means a piece of carved wood. These two images represent an act of carving and engraving. During carving and engraving, pieces of wood or stone fall away.
(The Complete I Ching, p. 206)

These explanations are based on the form as found in the Shuowen, which is written in small seal script.The Shuowen itself says:

裂也. 从刀从彔. 彔, 刻割也. 彔亦聲.
Split/crack. From 刀 ('knife') and 彔. 彔 means 'carve' and 'cut'. 彔 also indicates the sound.

When it comes to meanings of characters the Shuowen can be considered reasonably reliable, but for etymological information you should not turn to this book, the given explanations are often wrong or incomplete. But in the case of bo the Shuowen is right when it says that the 彔 part  represents the pronunciation.  We will talk about this later in this article.

The character bo in its complete form does not appear on bone inscriptions, but the component 彔 does. On bones it looks a bit like the small seal form. The 新編甲骨文字典 dictionary says about the form of this character:

象汲水之轆轤形, 象桔槔, 象汲水之具,  象水滴. 卜辭彔借用作麓, 彔、㯟、麓混用.
Picture of a winch for lifting water (from a well), is the handle, is the means which carries the water, are drops of water. In bone inscriptions 彔 is used as loan for 麓; 彔, 㯟 and 麓 are used mixed.
(新編甲骨文字典, p. 418)

The last three characters from this quote, 彔, 㯟 and 麓 are variant characters from each other, and all three mean '(a place at) the foot of a hill or mountain'. This is the meaning that is most used in bone inscriptions. All three characters are pronounced lu, and this is probably the reason why they are used as loans for each other. In later periods we find the component 彔 on bronzes in almost the same form as on bones, but then the most used meanings are lu 祿, 'good luck' and lu 麓, 'a name for an official position regarding mountains and forests' (金文常用字典, p. 712-713).

But is the component 彔 important for the meaning of the character bo 剝, the name of hexagram 23? We have seen that the description of the form, the shape of this character, does not have any connection to the meanings for which the component was used. This is a strong clue that this component (as the Shuowen indicates) has a phonetic function: it is a pointer to the pronunciation. Not that it ends here, in the case of 剝 it makes things more complicated. Most characters which have 彔 as (main) component are pronounced lu, but 剝 is pronounced bo or bao. This is probably a clue that 剝, or its component 彔, should be considered a loan for another character which has the sound bo, bao, or something close to that.

There are other facts which point to this. The Shuowen gives a variant of 剝 which contains the component bu 卜 (see the long image right to the quote from the Shuowen above, click to enlarge). Where the Shuowen gets this from is not known, there are no known texts in which this character is used. But there is one (yes, one) fragment of a bone inscription in which this character is used. Ma Rusen 馬如森 says of this character:

字象刀刻卜字之形，卜標聲，本義應是刻裂. (...) 卜辭義: 待考. “...剝...七月...”. 現只見此一條.
The picture of this character has the appearance of 'carving bone characters', bu 卜 marks the sound, the original meaning might be 'carve and split'. (...) Meaning on oracle bones: has yet to be researched. "...carve...seventh month..." This is the only line of text that we have.
(殷墟甲骨學-帶你走進甲骨文的世界, p. 304)

This little information would be hardly useful if we didn't have some other texts which, in combination with this variant ��, put the meaning of 剝 and hexagram 23 in a different light. For this we have to look into a few Yijing texts which have been excavated during archaeological digs in the last 30 years. The Fuyang Yijing which has been excavated in 1977 in the vicinity of Fuyang 阜陽 gives a different name for hexagram 23. In this variant text it is called pu 僕. The most significant meanings of this character are:

• 侍從，供役使的人
  a servant, a person who does labour
• 古代把人分為十等，僕為第九等
  with people one of ten ranks (between employer and employee; starting with the king and ending with the cheapest slave HM), pu 僕 is the ninth rank.
• 駕車的人
  driver
• 謙詞. 用於第一人稱
  humiliating title. Used in first person.
• 古代官名
  in antiquity the title of a government position (like driver, servant or slave;  Hucker, A Dictionary of Official Titles in Imperial China, p. 394 HM)
  (漢語大字典, p. 218)

These meanings show that a pu did not have a high position. But more important is the pronunciation of this character, pu, and the fact that it is another name for hexagram 23. The Fuyang Yijing is not the only source in which 剝 is replaced by 僕. The version of the Guizang 歸藏 which was excavated in 1993 does not contain hexagram 23, but there are sources which quote hexagram 23 from the Guizang - and mention that this hexagram is called pu 僕 (Han Ziqiang 韓自強, 阜陽漢簡《周易》研究, p. 121; Zhu Xingguo 朱兴国, 三易通义, p. 341).

The two characters are also exchanged in another excavated text. At the second line of hexagram 56 the text mentions 僕:

得童僕
Gets a young servant.

But the Mawangdui 馬王堆 version mentions 剝 instead of 僕 (Deng Qiubai 邓球柏, 帛书周易校释, p. 375).

Lu Deming 陸德明 (556-627) read 剝 as 撲, a variant of 僕, in Song M154 of the Shijing 詩經:

八月剝棗.....
In the eighth month we beat the jujube....

Lu translates 剝 as pu 撲, meaning 'to beat' (Karlgren, Loan Characters in Pre-Han texts, entry 1264. Karlgren does not agree with Lu's reading). 撲 is a variant of 僕 (阜陽漢簡《周易》研究, p. 121. In his translation of the Fuyang Yijing (forthcoming) Edward Shaughnessy translates 僕 also as 'to beat'). We also know that 剝 is used in the meaning of pu 攴, which means 'to beat' (漢語大字典, p. 346; Wang Li 王力, 王力古漢語字典, p. 73).

剝 and 僕 are exchangeable, which brings us to the earlier mentioned variant character from the Shuowen and the bone fragment, the character ��: the assumed pronunciation of this character, bu, is almost the same as the pronunciation of 僕, pu, which strengthens the link between the characters. But reading bo 剝 as pu 僕 has consequences for the translation of the text of hexagram 23. The character bo 剝 appears in five of the six line texts, and these texts will get another reading.

(3) 剝之.無咎.
剝 it. No mistake.

The character zhi 之 can have the meaning of 'it' as personal pronoun ('he makes it') at the end of a sentence, and in that case the word before it becomes a verb.

(6) 小人剝廬.
     The little man 剝 the hut.

Xiaoren 小人is a noun, just like lu 廬. Because of this the sentence gets the standard subject-verb-object pattern.

This shows that 剝 is a verb in the Yijing. The most used meanings of this character are 'peel/cut (fruit and vegetables), remove the outside, cut in halves', but a hut is not easily peeled or cut in halves. The Mawangdui text doesn't talk about a lu, 廬, a hut, but about a lu 蘆. The characters look almost the same, but the latter has the 艹 component instead of the 广 component. The component 艹 is the 'abbreviation' of the full form character 艸, and characters with this component often have to do with vegetation and crops, while 广 has to do with housing. According to the 漢語大字典 some of the meanings of 蘆 are:

• [蘆菔]菜名. 即蘿蔔
  lufu 蘆菔, the name of a vegetable, namely luobo 蘿蔔 (radish)
• 薺根
  the root of several kinds of plants
• 漏蘆
  the same as loulu 漏盧 (a plant with long stems and small flowers. Used for medical purposes)
  (漢語大字典, p. 3325)

The most plausible meaning might be the first one, 'radish'. Probably it refers to the white radish with large roots, which is quite common in China. In Song M210 from the Shijing 廬 can also be read as 'radish', where the traditional rendering is 'hut':

中田有廬(蘆), 疆場有瓜.....
In the centre of the field is the radish, at the borders the melons.....

The complete text of line six will then be translated as

(6) 碩果不食.君子得輿.小人剝廬.
     A large fruit is not eaten. The junzi obtains a carriage. The xiaoren cuts the radish.

Here we translate 剝 as 'to cut'. Let's see if this also holds for the other lines which have 剝:

(1), (2), (4) 剝牀.....
                 cut - bed .....

Chuang 牀 means 'bed', which would turn the translation of these three lines start with 'cut - bed', 'cut the bed' or something like that. That sounds a bit strange, 'bed' doesn't really fit 'to cut'. The MWD version doesn't talk about a bed but about zang 臧, a character with almost the same pronunciation. The Fuyang Yijing does mention a bed, but in his book 阜陽漢簡《周易》研究 Han Ziqiang 韓自強 gives a detailed exposé about homonyms and he concludes that characters like chuang 牀, zang 臧 and zhuang 壯 can all be read as qiang 戕, 'to kill' or 'to wound'. The composition 僕牀 in the Fuyang Yijing is read by Han as 'wounding the servant' or 'the wounded servant', and the harm to the servant is inflicted by beating him (as we have seen 剝/僕 is also used in the meaning of 撲 or 攴, 'to beat'). Han then subtly remarks that earlier many people arrived at statements that where not convincing, but because of the Fuyang and Mawangdui Yijings it suddenly is all so obvious. That is somewhat exaggerated, because the grammar of the line texts show that 剝/僕 should be translated as a verb and not as a noun, like Han does. If we sustain that for 剝/僕, but accept his assumption that 牀 should be read as 戕, 'to wound' (and Han knows to substantiate this quite well; it should also be noted that the component 爿 is a picture of a bed, and it is related to 疒, which on oracle bones depicted a person lying in bed; characters with this component often have to do with illnesses or other inflictions to the body), then the remaining lines are translated as follows:

(1) 剝牀以足.蔑貞.凶.
     By cutting wounded at the foot. Insignificant, contemptuous divination. Misfortune.

(2) 剝牀以辨.蔑貞.凶.
     By cutting wounded at the kneecap.
     (Following Han, who says that bian 辨 and MWD bian 辯 have to be read as loan for bin 髕)

(3) 剝之.無咎.
     Cutting it. No mistake.

(4) 剝牀以膚.凶.
     By cutting wounded at the jaws. Misfortune.
     (Following Han, who dictates that fu 膚 should be read as loan for fu 輔, 'jaw'. It can also mean 'the back of the knee'; 漢語大字典, p. 3533)

Conclusion
The contexts for which these line texts are meant are not explicitly indicated, as is so often the case with the Yijing. But there is a practice which is often mentioned in the Yijing and which could have a connection with hexagram 23: the practice of ancestor worship. We know that the ancestors often received copious offerings with all kinds of food - meat, fish, vegetables, fruit. The preparation of the food was also part of the ritual. Imagine that during the cutting of the food you would wound yourself: a bad omen: misfortune! At the third line it is going okay, so 'no mistake'. At the sixth line the meaning of the text is also symbolic: a large fruit will have to be cut before it can be eaten. In the same text, as well as in other instances in the Yijing, the junzi is mentioned against the xiaoren. The junzi has transport and does not have to work, the hard labour passes him by. The xiaoren, the common people have to do the hard work. Both have there function and use, and for the right execution of the ritual both will have to take their proper position. That is how the high is connected with the low.

Irian, kijkend naar een koor op tv wat zingt "iedereen wil vrede":

Als je vrede wilt moet je niet voor macht kiezen.

(Irian, while watching a choir on tv singing 'everybody wants peace': "If you want peace you must not choose for power.")