Early and Late Zi Hour Theory
Deep dive into the Early and Late Zi Hour theory in BaZi astrology, understanding the differences and applications of traditional and modern Zi hour calculation methods
What is the Early and Late Zi Hour Theory?
In BaZi astrology, there has been ongoing debate about the attribution of Zi hour (23:00-01:00). The traditional method attributes the entire Zi hour to the next day, while the Early and Late Zi Hour theory divides Zi hour into two parts: Late Zi (23:00-24:00) belongs to the current day, and Early Zi (00:00-01:00) belongs to the next day.
This difference may seem minor, but it produces different day pillar results in actual BaZi calculations, thereby affecting the interpretation of the entire chart. As the ancient saying goes 'Even immortals cannot determine Zi hour destiny', this issue has been debated since the birth of BaZi astrology and continues to this day.
Ancient literature provides important references for this controversy. The Tang Dynasty's 'New Book of Tang - Calendar Tables' records 'ancient calendars divide days, starting at the middle of Zi hour', indicating that ancient calendars began the day at the midpoint of Zi hour. The Song-Yuan 'Revolutionary Elephant New Book' further clarifies that 'the upper half of Zi hour before midnight belongs to yesterday, the lower half after midnight belongs to today', which is the historical basis for modern early-late Zi hour theory.
Zi Hour Timeline Comparison
The traditional Zi hour system follows ancient time division methods, treating Zi hour as a complete time period belonging to the next day, reflecting traditional astrology's concept of time.
The Early and Late Zi Hour system is based on modern time concepts, using midnight as the boundary, which better aligns with modern people's time perception habits.
Comparison of Two Methods
Click the cards below to learn detailed information about each method
Traditional Zi Hour System
23:00-01:00 → Next Day
23:00-01:00 entirely belongs to next day, following ancient time division methods
Belongs to January 2nd Zi hour
Belongs to January 2nd Zi hour
Early and Late Zi Hour System
23:00-24:00 → Current Day | 00:00-01:00 → Next Day
00:00 as boundary point, belonging to two days, conforming to modern time cognition
Belongs to January 1st Zi hour (Late Zi)
Belongs to January 2nd Zi hour (Early Zi)
Method Description
23:00-01:00 entirely belongs to next day, following ancient time division methods
The traditional Zi hour system follows ancient time division methods, treating Zi hour as a complete time period belonging to the next day, reflecting traditional astrology's concept of time. This method maintains the integrity of ancient astrological theory and is consistent with traditional classics.
Pros and Cons Analysis
Pros
Theoretically complete, consistent with ancient texts, suitable for academic research
Cons
Differs from modern time concepts, higher learning threshold
Practical Application Guide
How to choose the appropriate calculation method in actual BaZi calculations
Traditional School Recommendations
Suitable for traditional astrology academic research and ancient text verification, maintaining theoretical system integrity
Modern School Recommendations
Conforms to modern time concepts, easy to understand and accept, suitable for modern astrology practice
Practical Advice
It is recommended to understand both methods and choose the appropriate system based on actual verification results
Historical Records
「In ancient calendar systems, the day begins at the middle of Zi hour.」
—— New Book of Tang - Calendar Tables
The Tang Dynasty's 'New Book of Tang - Calendar Tables' clearly records that ancient calendar systems began the day at the midpoint of Zi hour (midnight). This provides important historical basis for modern early-late Zi hour theory.
Song-Yuan Literature
「The upper half of Zi hour before midnight belongs to yesterday, the lower half after midnight belongs to today.」
—— Revolutionary Elephant New Book
The Song-Yuan period 'Revolutionary Elephant New Book' further clarified the attribution of Zi hour, which is the historical origin of modern early-late Zi hour theory.
Conclusion and Recommendations
Regardless of which method you choose, consistency should be maintained. Different calculation methods may produce different results, the key lies in the internal logic of the theoretical system and practical verification.
In the FateMaster system, you can freely choose which calculation method to use.