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天德月德 Virtue Stars (Tiān Dé Yuè Dé) ​

The Virtue Stars (德星) are among the most auspicious markers in the Chinese calendar system. Each month has a Heavenly Virtue (天德) and a Monthly Virtue (月德), determined by the month's Earthly Branch. When a day's stem or branch matches a virtue star, it is considered especially favorable for important activities. Each virtue star also has a combination partner (合), derived through the Five Combinations (五合) relationship.

See also: Almanac Flags · Day Fitness Cycle · Deity Directions

月德 Monthly Virtue ​

Derived from the yang stem of the month's three-harmony element.

Three-Harmony GroupMonth Branches月德 (Stem)
火 Fire寅, 午, 戌丙
木 Wood亥, 卯, 未甲
水 Water申, 子, 辰壬
金 Metal巳, 酉, 丑庚

月德合 is the 五合 (stem combination) partner of the 月德 stem:

月德丙甲壬庚
月德合辛己丁乙

天德 Heavenly Virtue ​

A traditional 12-entry lookup. The value can be either a stem or a branch.

Month Branch寅卯辰巳午未申酉戌亥子丑
天德丁申壬辛亥甲癸寅丙乙巳庚

天德合: When 天德 is a stem, the partner is its 五合 pair. When 天德 is a branch, the partner is its 六合 pair.

Month Branch天德天德合Combination Type
寅丁壬五合 (stem)
卯申巳六合 (branch)
辰壬丁五合 (stem)
巳辛丙五合 (stem)
午亥寅六合 (branch)
未甲己五合 (stem)
申癸戊五合 (stem)
酉寅亥六合 (branch)
戌丙辛五合 (stem)
亥乙庚五合 (stem)
子巳申六合 (branch)
丑庚乙五合 (stem)

Stem Combinations (五合) ​

PairElement Produced
甲 ↔ 己土 Earth
乙 ↔ 庚金 Metal
丙 ↔ 辛水 Water
丁 ↔ 壬木 Wood
戊 ↔ 癸火 Fire

Branch Combinations (六合) ​

PairElement Produced
子 ↔ 丑土 Earth
寅 ↔ 亥木 Wood
卯 ↔ 戌火 Fire
辰 ↔ 酉金 Metal
巳 ↔ 申水 Water
午 ↔ 未火 Fire

API ​

typescript
import {
  getMonthlyVirtue,       // Branch → Stem
  getMonthlyVirtueCombo,  // Branch → Stem
  getHeavenlyVirtue,      // Branch → Stem | Branch
  getHeavenlyVirtueCombo, // Branch → Stem | Branch
} from 'stem-branch';

getMonthlyVirtue('寅');      // → '丙'
getMonthlyVirtueCombo('寅'); // → '辛'
getHeavenlyVirtue('寅');     // → '丁'
getHeavenlyVirtueCombo('寅'); // → '壬'

See Also ​