Cui Wenzi was a native of Taishan. His family had long been devoted to the Huang-Lao tradition of Taoism, and he lived beneath Qianshan. He made yellow powder and red pills, sold medicine in the city market, and claimed to be three hundred years old. When an epidemic broke out and tens of thousands died, local officials came to request a cure. Wenzi held up a red flag and tied yellow powder to it as he paraded through people's doorways. Those who drank the powder were immediately cured, and tens of thousands were saved. Later he left for Shu to sell yellow powder. The world valued Cui Wenzi's red pills and yellow powder highly — they were almost miraculous.

Cui Wenzi stands in a long lineage of medicine-making immortals in the Lie Xian Zhuan. Gui Fu made cassia pills still available in Jingzhou generations later, while Ren Guang sold cinnabar pills for 89 years unrecognized. But Cui Wenzi's medicine was not sold for profit — it was deployed in a public health crisis, carried door to door under a red flag, freely given to all who needed it.

Like the Wine Connoisseur, who predicted a famine and saved the people of Liang, Cui Wenzi used his Taoist knowledge in direct service of the living. And like Anqi Xiansheng, who sold medicine along the Eastern Sea for a thousand years, he quietly moved on — leaving behind only the legend of his red pills and yellow powder.

Cui Wenzi attained the Dao, his techniques combining secrecy and profundity. When pestilence descended to cause death, he grieved deeply with a compassionate heart. The red flag like lightning, divine medicine arriving swiftly. At one time he saved many lives; his deeds would serve as an example for generations to come.

The eulogy's phrase "a compassionate heart" is the key to Cui Wenzi's story. In the Taoist tradition, compassion is a form of cosmic attunement — the sage feels the suffering of others because he has dissolved the boundary between self and world. His red flag moving like lightning through the streets is an image of the Dao in action: swift, purposeful, leaving no one behind.