Mulberry-tree caterpillars are silkworms. What does the use of this example in a classic text indicate about the importance of that creature to Chinese culture? Why would the Han penal code exonerate a stepfather for harboring his son even though the son had committed a serious crime?
This is an excellent question, and the answer goes back to the Qin and Han dynasties. In fact, the mention of the importance of the silkworm in these very important time periods can be traced back to Shi Jing, and The Canon of Odes, which is poetry published as early as the years 1000 to 600 B.C. (!)
This book of odes is an anthology of hymns and songs. There are 311 poems in it, some which have no text in it, just other forms of representational thought. This is the book with which Chinese literature actually begins. These works were collected from the epicenter of Chinese civilization, which is he Valley of North China and the lower HuangHe, or Yellow river.
In true Chinese tradition, these poems would depict a stamp of life in a typical day in the empire. An important part of civilized culture was the production of silk. Silk was considered the most important textile in their world and, by default, the silkworm was given utmost importance as a small but valuable asset in Chinese society. An essential part of the process was the actual collection of mulberry leaves to give to the silkworms.
Now, to the Western reader (us), this may seem a bit too ceremonial: Giving an insect something to do is not a venerable act in our instantly-gratified society. However, the Eastern point of view is quite different. Minimalism is king, and special consideration is given to all creatures, big and small. Hence, the silkworm, its "duty" to society, and the act of aiding it, are all great factors to take into consideration.
Han Penal Code
Let's now look at the Han penal code. Like the article states, Confucian philosophy was infused into the harsh, Chinese judiciary system in order to make sense out of the sentencing awarded to criminals.
It is a wise move, because sentencing was entirely formulaic at one point and did not give any afterthought to humanitarian factors. Inquiry would consist on a judge conducting an investigation and stating rules, rather than the system of checks and balances that we know in the Western culture, where evidence is presented in court, and a jury of one's peers decides the fate of an accused criminal.
Granted, neither of the two systems is flawless. The human factor is ever-present, mistakes are made, and truths are often misrepresented. However, the Chinese system tries to adjudicate rationale to its final decisions. It does so by using these philosophical devices, such as the allegorical mention of the silkworm.
The case for the stepfather
The rationale presented in the case of citizen A and citizen B states that the later, citizen A, raised B as his own son. When B grows into an adult, he makes the bad decision of committing a crime. His stepfather covers for him out of a sense of filial and paternal duty, thus preserving the family connection. It is not an ethical decision, but it is one made from another place in one's ethos: duty.
The court states that he should be tried as guilty for covering for the son. However, the Confucian element of the case states that the man was doing what other elementals of nature would have done: save their own. Even when the silkworm has its offspring, another insect, the wasp, (granted, of lesser value) is the one that protects it. Nevertheless, the act is done. People take care of one another just like these bugs do. It no longer touches on the realms of the law, nor those of human ethics. This is nature, not nurture: this is what living beings (big and small) do.
In the court it was shown that A should not be found guilty for this very reason. Even though the parent covered for the son, he was not responsible for the act committed by another person. The only thing the father is guilty of is obeying the flawed emotional system that makes us what we are: human. He did not kill and he did not commit any crime. There is no way that he could have known that the child that he raised as his own, someone he gave a second chance in life, would turn around and make such a bad choice. He is unable to predict or control what someone else does. All that he can do is be there for the individual that he promised to raise and protect. That is all he can do as a human, as a citizen, and as a father. Confucian law saw that this was indeed the case, and this is why he was exonerated.