The Classics · 1 of 4
Yuan Hai Zi Ping 渊海子平
where the Day Master method begins
What it is
The oldest systematic text of the method modern BaZi practises — compiled in the Song dynasty from the teachings of Xu Zi Ping, the figure the whole school (子平法) is named after. Before Zi Ping, fate-reading centred on the year of birth; the revolution this text codifies is reading everything from the day stem — the Day Master — a change so complete that today it isn't even argued, just assumed.
What's in it
The mechanics later texts take for granted: plotting rules, hidden-stem tables, the Ten Gods and their classical aliases, the first systematic structure catalogue, and a large body of verse-form judgment formulas (赋) that centuries of students memorised. It is less a single authored book than the tradition's founding compilation — layered, occasionally inconsistent, and indispensable.
One famous idea
The premise itself: 以日为主 — "take the day as the master." Every glossary page on this site quietly assumes this one Song-dynasty sentence.
How to read it today
As a reference, not a novel: its tables and definitions are load-bearing; its case verses need a teacher's unpacking, because they compress judgments whose conditions the text doesn't always state. That unpacking — which formulas the lineage keeps, which it qualifies — is exactly what changes between schools. Yixin Academy teaches from this foundation in Mandarin, the language the text actually lives in.
Want this text unpacked line by line, against a real chart?
learnwithyixin.com/courses →What is Yuan Hai Zi Ping?
The oldest systematic BaZi text — compiled in the Song dynasty from the teachings of Xu Zi Ping — that codified reading a chart from the day stem (the Day Master) rather than the birth year, the change the whole modern method is built on.
Who was Xu Zi Ping?
The Song-era master to whom the day-centred method is attributed and after whom the entire school (子平法, "Zi Ping method") is named. Historical detail on him is thin; the attribution is traditional.