Years ago for my own interest I translated Ch. 13, Section 12 from Zheng Manqing’s Thirteen Chapters. This is the section expanding on “using four ounces to deflect a thousand pounds.” I’ve since had discussions with other taijiquan enthusiasts about some of the words and phrases in that section. One friend asked about Zheng’s use of “an old rotten four-ounce rope” in the passage below about “leading.” He said it didn’t make much sense to him.
“As for the method of leading (qian 牽), supposing we pierce the nose of a thousand pound ox, [using] a cord of no more than 4 oz. [strength]. Using a cord of four ounces, [one can] lead a thousand pound ox to the left or right as one wishes. She may want to flee, but she cannot succeed. Now in leading, [one must] lead precisely [by] the nose. If one leads by her horn or her leg, it won’t do (or, ‘she won’t move’: bu xing ye 不行也). This leading is done in accordance with its method (以其道) and in accordance with its location (以其處). Hence, the ox can be lead with a four ounce cord. If it were a thousand pound stone horse, could one still lead it using an old rotten four ounce rope (si liang zhi siu suo 四兩之朽索)? Impossible! This is a difference in effect between the animate and the inanimate.”
My response follows:
Knowing Zheng Manqing's proclivities in writing, I think his use of the wording "old rotten rope" was well considered and deliberate. There is a chengyu, 朽索馭馬 xiǔ suǒ yù mǎ: drive a horse with rotten reins," that means to manage a situation that is severely perilous. See: http://www.zdic.net/c/d/172/386438.htm
It traces back to the Book of Documents 尚書, from a section called the Songs of the Five Sons. The first son speaks of the tremendous responsibility he feels for governing, and the respect and awe he feels for the people:
'In my dealing with the millions of the people,
I should feel as much anxiety as if I were driving six horses with rotten reins.
The ruler of men -
How should he be but reverent (of his duties)?'
--James Legge, trans. See also: http://ctext.org/shang-shu/songs-of-the ... all#result
The anxiety of driving six horses with rotten reins in this song is: 懍乎若朽索之馭六馬
Yet, being "reverent of his duties," he carries on the task. It speaks of an appreciation of the precarious situation of governing. The phrase 懍乎若朽索之馭六馬 is quoted countless times by later generations, including the Song philosopher Zhu Xi. The trope of holding the reins as a metaphor for governing is common in early texts. In the Huainanzi, for example, there's a passage, "The government of a sagacious ruler is like the charioting of Tsao Fu. He controls the carriage from the reins and the bit, and he regulates the tightness of his grip on the reins from his sensitivity to the response of the horses' lips." --Roger Ames, trans., The Art of Rulership: A Study of Ancient Chinese Political Thought, p. 192.
What struck me the first time I encountered this passage was how tactile it is, and how it speaks of a responsive relationship with the horse. I think anyone familiar with the taiji notion of tingjin would recognize a certain resonance. So I think it's within reason to speculate that Zheng had something of this imagery in mind when he chose to use the 朽索 wording. He took it even further, however, in using it to illustrate the need for a sensitive tactile awareness required to enlist just the right amount of leading force to engage and maintain the connection with the opponent's force.
Here’s where I think the reader needs to do some extrapolative thinking. On the face of it, describing the rope as old and rotten, and as a “four ounce rope” seems odd. My sense of it is that Zheng certainly isn’t describing the weight of the rope; he’s referring to how much force the old rope can sustain. What he’s describing is a tactile phenomenon. A herd boy who has an old frayed rope knows that if he jerks or pulls with too much force, the rope will break. But even this old rotten rope will still serve his purpose if he uses the bare minimum leading force. The nose of the ox is a very sensitive spot. When I think of it in these terms, it makes quite a lot of sense, and is similar to classical taiji injunctions about drawing a silk fiber. If you use the appropriate gentle force, smoothly and consistently, you can draw the fiber out in one piece. If you jerk or interrupt the flow it will break. So Zheng’s illustration of the stone horse vs. a living animal is very instructive and clever!