The Book of the Nine Elixirs (Jiudan jing) is the main extant text of the Great Clarity (Taiqing), the earliest identifiable tradition in the history of Chinese alchemy. In its original form, this work dates from about 200 CE. It describes the preparation of nine elixirs, paying particular attention to the ritual context of the alchemical practice.
The main stages of the process are the ceremony of transmission from master to disciple, the establishment of the ritual area, the choice of an auspicious time, the compounding of the elixir, its offering to the gods, and its ingestion. It is this entire process, and not only the actual compounding of the elixirs, that constitutes the alchemical practice.
On the other hand, neither the Book of the Nine Elixirs, nor any other Great Clarity source, describes the alchemical process using the patterns, imagery, and language of Chinese cosmology and its system of correspondences. These features of the cosmological system become important in the history of Chinese alchemy only from the Tang period onward (approximately from the 7th century). They were first used in Waidan (External Alchemy), and paved the way for the emergence of Neidan (Internal Alchemy, documented from the 8th century).
When these new forms of alchemy became widespread, the Great Clarity tradition declined. No original text belonging to this tradition was composed in the Tang period or later. The Book of the Nine Elixirs is one of the few sources that provide glimpses into the earliest stages of the Chinese alchemical tradition.