It means: In ancient times, a gourd was hung in front of the Chinese medicine shop. Gourd, called "pot" in ancient times, commonly known as gourd melon, is one of the symbols of ancient Taoism. Therefore, later generations all call those who sell medicine and practice medicine "hanging pots".

source: the book of the later Han dynasty-biographies of alchemy-Fei changfang, by Han Fan Ye and others.

Allusions:

It's probably all about a plague in Henan in a summer of Han Dynasty, and many people died and could not be cured. One day, a magical old man came here. He opened a small Chinese medicine shop in an alley and hung a medicine gourd in front of the door, which contained pills to cure this plague.

This "pot Weng" is full of stunts and is charitable. Whenever someone comes for medical treatment, the old man takes a pill from the medicine gourd and lets the patient take it with warm water. In this way, people who drank this "pot Weng" medicine got better one by one.

There was a man named Fei Changfang from Runan (now Gucheng Village, Sheqiao Town, Pingyu County, Henan Province). When he saw this old man jumping into the pot after the people dispersed, he felt very strange, so he took his food and drinks to visit, and the old man invited him to join him in the pot. From then on, Fei Changfang followed his teachings, and Hu Weng taught him the art of "hanging a pot to save the world".

Extended information

Hu Gong and Fei Changfang were famous doctors in the Eastern Han Dynasty, and the medicine gourd was just a medicine pot. Or it's just a "trick" to practice medicine and sell medicine.

However, there are still profound meanings for doctors to hang medicine gourd: first, to show the world their great wish of "hanging pot to save the world"; Second, we should pay attention to the practical value of gourd: it is indeed better to preserve drugs with gourd than other containers such as iron boxes, pottery pots and wooden cases, because it has strong sealing performance, moisture is not easy to enter, and it is easy to keep drugs dry.

It is known from historical records of past dynasties that medical practitioners in ancient times carried gourds wherever they went. For example, Sun Simiao, the king of medicine in the Tang Dynasty, always hung a gourd when collecting medicine. Moreover, gourd can not only hold medicine, but also be used as medicine to cure many diseases.

Reference: Baidu Encyclopedia-Curling Pots to Help the World.