Di Tian Sui (滴天髓)
Drop of Heaven Marrow
Author: Attributed to Liu Bowen, Ming Dynasty; annotated by Ren Tieqiao, Qing Dynasty
Period: Ming Dynasty (~14th c.); Qing annotation (~19th c.)
The most authoritative classic on Bazi theory, focusing on Day Master (日主) strength assessment, the concept of rooted vs. floating elements, and the balance of Yin and Yang within a birth chart. Ren Tieqiao’s annotated edition remains the standard reference for serious practitioners.