Practical Guide to the Great Cavern Scripture 太上长文大洞灵宝幽玄上品妙经发挥

The author is unknown, and it was presumably compiled between the Tang Dynasty and the Song Dynasty.

Consisting of one scroll, it is included in the Tai Xuan Section within the Daoist Canon (The Daozang).

This work is a commentary on The Long Text of the Great Cavern Scripture.

Practical Guide to the Great Cavern Scripture

The author holds that the Neidan (Internal Alchemy) methods expounded in the original scripture are "profound and abstruse in meaning", fearing that later practitioners would find it difficult to initiate the practice. Thus, the author established a regimen based on thirty days to clarify the alchemical cultivation methods for each day. The text is divided into thirty chapters, and each chapter appends seven-character odes or four-character eulogies to the original scripture, explaining the progress of alchemical refinement.

It stipulates that thirty days constitute a minor achievement, sixty days a major achievement, and ninety days a complete celestial circuit. The cultivation is accomplished over nine years, amounting to a total of three hundred and sixty celestial circuits. Only then can one attain abundant Qi and a perfected spirit, the great elixir be formed and transformed, and the Dao be attained to become a true immortal.