Xuan Kong Da Gua Date Selection (玄空大卦擇日法)
The Xuan Kong Da Gua (XKDG) date selection method is an advanced technique from the San Yuan (三元) school of Feng Shui, tracing its lineage to Jiang Da Hong (蔣大鴻) of the late Ming / early Qing Dynasty. Unlike the more accessible Dong Gong or Jianchu systems, XKDG operates on the hexagram (卦) level — mapping each of the 60 Jiazi GanZhi combinations to a specific I Ching hexagram and extracting two numeric values: the Gua Qi (卦氣) and the Gua Yun (卦運).
Origin and Lineage
Jiang Da Hong is considered the patriarch of the San Yuan Xuan Kong school. His teachings, preserved in cryptic verse form in texts such as the Tian Yu Jing (天玉經) and Du Tian Bao Zhao Jing (都天寶照經), encode the principles of flying-star Feng Shui and the Da Gua system. The date selection application of XKDG was developed by later disciples who applied the same hexagram-number theory used in site analysis to the temporal domain — evaluating the quality of a Four Pillars date chart through the lens of Gua Qi and Gua Yun relationships.
The 60 Jiazi Mapping
Each of the 60 Jiazi GanZhi combinations is mapped to a specific hexagram, along with two numeric values:
- Gua Qi (卦氣): A number from 1 to 9 derived from the Pre-Heaven (先天) Luo Shu position of the upper trigram. This represents the elemental quality of the hexagram: 1,6 = Water; 2,7 = Fire; 3,8 = Wood; 4,9 = Metal.
- Gua Yun (卦運): A number from 1 to 9 representing the period (運) assignment of the hexagram. This determines the temporal compatibility of the hexagram with the current macro-period (e.g., Period 9, 2024–2043).
Dual-Track Analysis
XKDG evaluates a date on two parallel tracks:
- Gua Qi Track: Examines the elemental relationships between pillar pairs. Auspicious relationships include He Shi (合十, sum = 10), Sheng Cheng (生成, He Tu pairs: 1-6, 2-7, 3-8, 4-9), He Wu (合五, sum = 5), He Shi Wu (合十五, sum = 15), Tong Gua (同卦, same number), and Dian Dao Ai Xing (顛倒挨星, reversed pairs: 1-3, 2-4, 6-8, 7-9).
- Gua Yun Track: Examines the same relationships between period numbers. A date that shows He Shi on both the Qi and Yun tracks is considered exceptionally auspicious.
Key Auspicious Patterns
- 一卦純清 Yi Gua Chun Qing (Pure Single Hexagram): All four pillars share the same Gua Qi number. This is the most auspicious configuration — extremely rare.
- 合十 He Shi (Sum of Ten): Two pillars whose Gua Qi numbers sum to 10 (e.g., 1+9, 2+8, 3+7, 4+6). Multiple He Shi pairs strengthen the chart significantly.
- 生成 Sheng Cheng (He Tu Generation): Two pillars forming a He Tu pair (1-6, 2-7, 3-8, 4-9). This represents generative, productive energy.
- 顛倒挨星 Dian Dao Ai Xing (Reversed Flying Stars): Pairs (1,3), (2,4), (6,8), (7,9) — representing the reversed star path, a secondary auspicious structure.
Mountain Flow Analysis (Sheng Ru / Ke Chu)
When the mountain (sitting direction) of a property is known, its GanZhi can be mapped to a Gua Qi element. The interaction between each pillar's element and the mountain's element determines the flow:
- Sheng Ru (生入): The pillar generates energy that flows into the mountain — auspicious, nourishing.
- Ke Ru (克入): The pillar controls the mountain — inauspicious, suppressive.
- Sheng Chu (生出): The mountain generates energy that flows out to the pillar — draining, mildly inauspicious.
- Ke Chu (克出): The mountain controls the pillar — strongly inauspicious, destructive.
- Bi He (比和): Same element — neutral to mildly positive.
Worked Example
Consider a date with Four Pillars: Year 甲子, Month 丁丑, Day 庚午, Hour 壬申. Looking up the table: 甲子 → Gua Qi 1, 丁丑 → Gua Qi 7, 庚午 → Gua Qi 9, 壬申 → Gua Qi 6. Pairs: Year-Month (1+7=8, none), Year-Day (1+9=10, He Shi!), Year-Hour (1+6=7, Sheng Cheng!), Month-Day (7+9=16, none), Month-Hour (7+6=13, none), Day-Hour (9+6=15, He Shi Wu!). This date has strong auspicious relationships on the Qi track — He Shi + Sheng Cheng + He Shi Wu — and would rate as 吉 (Good) or higher depending on Yun track and mountain compatibility.