Tao Hongjing said: When kings, dukes, and nobles prepare medicine, subordinates secretly swap the good herbs for inferior ones, which ultimately goes undetected. Using such medicine to treat illness makes it difficult to expect efficacy. I believe that "personally overseeing the preparation of medicine" does not mean supervising every step oneself, but rather entrusting the task to someone who is both close and trustworthy, so that it can be safely delegated. If the issue were merely secret swapping, that would still be a minor matter. However, there are even more severe cases where enemies harbor jealousy, or concubines compete for favor, creating internal rifts and harboring hidden malicious intent. Some bribe deceitful physicians, while others seduce maids or servants to add arsenic (Pishuang) or, taking advantage of convenience, introduce gu poison. It is frequently observed that patients fail to detect these manipulations in time and are repeatedly victimized. By the time the truth comes out, it is too late to regret. Therefore, caution is indispensable.