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Mr. Chunyan Wu authored "Essentials of Health Preservation" (Yangsheng Leyao) with over a hundred entries. After the woodblocks were carved, Mr. Yutian read it and sighed, saying: "How benevolent is Mr. Wu's heart! Only such a person can speak of medicine."

Generally speaking, practitioners of medicine, upon obtaining an effective prescription, would hide it in their chests or boxes, fearing that if patients knew of it, it would hinder sales; they also feared that if fellow practitioners knew, it would hinder exclusive sales. Some even changed "chewing" (ju) to "powder" (mo), or altered "yellow" (huang, likely referring to a yellow herb or color) to "dark/black" (xuan), claiming this way others would not recognize them. Alas, are these truly physicians?

Mr. Wu came from a prestigious family in Huizhou. In his youth, he studied books with the ambition of becoming a scholar proficient in the Classics, but due to illness, he could not realize this. He heard that Master Lu Fuye from Huzhou was a renowned physician, so he took him as a teacher and received authentic transmission before returning home. People from north and south of the Yangtze River, regardless of distances of hundreds of li, would come running to his hall to kowtow for treatment, and many were saved by him. Considering his beneficence not yet extensive enough, he traveled to the regions of Yan, Qi, and elsewhere. He resided in Linqing for four years. When preparing to return south, local merchants requested he stay, but Mr. Wu refused. Well-wishers tried to detain his journey but failed, instead requesting: "Please write a book for us." Unable to refuse the collective request, Mr. Wu wrote the book "Leyao". This was perhaps merely offering some surplus knowledge to supplement people's daily needs. Although it did not exhaust all that he learned from Master Lu, the prescriptions and herbs in this book were indeed accurate and appropriate.

With the publication of this book, patients from all directions could be cured without necessarily needing a personal consultation (or had clear guidance for healing), and Mr. Wu's medical practice spread more widely. Alas! Ancient medical texts, when obtained by worldly physicians, were kept secret; Mr. Wu, upon obtaining them, sought to transmit them. His intention differs as much as heaven and earth. Thus it is said: How benevolent is Mr. Wu's heart! Moreover, his book incorporates verified experiences from past sages, allowing it to be disseminated far and wide. Who knows if readers of future generations will not feel that figures like Liu Hejian and Zhu Danxi have produced new case studies of such brilliance?

Mr. Yutian believed that carving this collection was convenient, and thus wrote this preface at the request.

On the auspicious day of the first month of the Ji Zi year (1564) of the Jiajing era, written at Duizhu Shantang.

What is called "Essentials of Health Preservation" (Yangsheng Leyao) is the classification of essential health preservation methods. Without classification, clarity is lacking; without essentials, precision is lacking. The reason for compiling this work regarding "classification" (Lei) is to separate subjects and arrange them comparatively. It begins with cultivating and absorbing essence and qi to prevent disease before it takes shape, hence classified. Next, it involves extracting and refining elixirs to reclaim the primordial spirit, also classified. Improper diet and daily use may lead to illness, classified accordingly; improper sexual conduct may lead to premature death, classified accordingly. Ancient texts had classifications for wind, cold, summer heat, and dampness, but did not distinguish the four seasons; here, the four seasons are classified separately. Ancient texts had sections on aiding women and nurturing children, but did not cover elderly care; here, elderly care is added. These are the principles of "classification".

The term "essentials" (Yao) refers to selecting the purest essence and summarizing it concisely. Medical texts often accumulate formulas and herbs chaotically without limit, lacking precision. "Essentials" summarize from the perspective of precision. It is like gathering jade from Jing Mountain while discarding stone, or collecting pearls from Sui while rejecting fish eyes. These are the principles of "essentials".

Classifying the essentials leads to precision and clarity; action yields results; households are free from pain; thus, they become good physicians.

Carved by Zhang Song of Wujun.