On the basis of certain formulating principles, a formula is combined of proper medicinals in deliberate doses which are selected according to the condition of disease after differentiating syndrome, identifying causes of disease and determining therapeutic methods.

The Basic Questions -Great Treatise on the Essentials of Supreme Truth ( Sù Wèn-Zhì Zhēn Yào Dà Lùn , 素问·至真要大论) indicated that“ The medicinal aiming at the main syndrome is called the chief, the medicinal assisting the chief medicinal is called the deputy, the medicinal responding to the deputy medicinal is called the envoy. ”(主病之谓君，佐君之谓臣，应臣之谓使) This is the principle of composing a formula.

About two thirds of the 314 prescriptions recorded in the Discussion on Cold Damage ( Shāng Hán Lùn , 伤寒论) and in the Essentials from the Golden Cabinet ( Jīn Guì Yào Lüè , 金匮要略) compiled by Zhang Zhong-jing in the Han Dynasty are based on the above principle.

In the Important Formulas Worth a Thousand Gold Pieces [for Any Emergency] ( Bèi Jí Qiān Jīn Yào Fāng , 备急千金要方) compiled by Sun Si-miao and the Arcane Essentials from the Imperial Library ( Wài Tái Mì Yào , 外台秘要) by Wang Tao in the Tang Dynasty, many effective formulas are composed rigorously of the chief, the deputy and the envoy medicinals.

It indicates that “the chief, deputy, assistant and envoy” (君臣佐使) theory of composing a formula had been applied widely by many doctors in the Han and Tang Dynasties.

During the Song , Jin and Yuan Dynasties, Cheng Wu-ji compiled the Clarification of the Theory of Cold Damage -Treatise on Prescriptions ( Shāng Hán Míng Lĭ Lùn- Yào Fāng Lùn, 伤寒明理论·药方论) to discuss the principle of syndrome differentiation and formulation in the Discussion on Cold Damage , and launched into the research on the theory of prescription formulation, and popularized the theory of formulation from the Inner Classic ( Nèi Jīng , 内经) for successive doctors in creating new formulas.

Thereafter, many doctors, such as Zhang Yuan-su, Li Gao, Wang Hao-gu, He Bo-zhai, Xu Hong, Wu Kun, Wang Ang, Ke Qin, etc. individually developed and contributed to the principles of composing formulas in theory and practice, and enriched the theories of composing formulas, thereby the “chief, deputy, assistant and envoy” theory was enhanced further in composing and applying formulas.

Since the founding of the People’s Republic of China, with the establishment of Chinese Medicinal Formulas as a subject, the compatible theory and methods of formulas were summarized and studied systematically. Especially, experimental researches on formulas were developed deeply to reveal many scientific connotations of the principle “chief, deputy, assistant and envoy” in composing formulas.

In the national medical college textbook for the Chinese Medicinal Formulas versions 1-5 and in the teaching material of the general higher education on Chinese Medicinal Formulas, the theory of “chief, deputy, assistant and envoy” is believed as the principle of composing formulas, and it is held up as the guide for the research on compatibility theory and methods of formulas, and has become an important topic in modern research on formulas.

It has taken a long period to realize, practise and put forward the principle of “chief, deputy, assistant and envoy” in composing formulas, the views of many doctors on this principle have been varied during this period, and the composition of some formulas can not be explained ideally by this principle. Thus, there are some difficulties in systemic collating and modern researches.

In this chapter, we will discuss this principle from the meaning of the “chief, deputy, assistant and envoy” theory, the different beliefs of many doctors, the development and outlook of its research. cPmrOwd0hoo3Jc0jrsdcRkRbZOd4TTYd3eIiPO4XD/6edhRNlxfcyCfMSR3p85uy