《子平集要》Zi Ping Ji Yao  is a compilation of Zi Ping theories and methods during Ming dynasty.  The last published version is from Qing dynasty Kang Xi Emperor’s Internal Courts 清康熙內府精抄本.

In its introductory chapters, the (unknown) author discussed the origination of destiny reading from Yi principles:

“禄命之说于易理亦有合者，盖岁日主于日，为阳，月 辰主于月，为阴，两仪之象也。”

There is a close relationship between destiny reading and Yi principles.  The Year Pillar and the Day Pillar are generated from the Earth’s movements in reference to the Sun (Yang).  While, the Month Pillar and Hour Pillars are defined by the cycles and phases of the Moon (Yin).  (The Chinese calendar is a luni-solar calendar.)

“岁为太阳，日为少阳，月为太阴，辰为少阴，四象之象也。”

The Year Pillar as Greater Yang, the Day Pillar as Lesser Yang,  the Month Pillar as Greater Yin while the Hour Pillar is Lesser Yin – the images of the Four Planes.

“岁之干阳支阴，乾坤也，父母也。”

The Heavenly Stem of the Year Pillar is Yang (Qian-Father) and its Earthly Branch is Yin (Kun- Mother).

“月之干阳支阴，震巽也，长男长女也.”

The Heavenly Stem of the Month Pillar is Yang (Zhen Gua-Eldest Son) and its Earthly Branch is Yin (Xun Gua- Eldest Daughter).

“日之干阳支阴，坎离也，中男中女也。”

The Heavenly Stem of the Day Pillar is Yang and represented by Kan Gua- the Middle Son, and, its Earthly Branch is Yin, represented by Li Gua- the  Middle Daughter).

“辰之干阳支阴，艮兑也，少男少女也。”

The Heavenly Stem of the Hour Pillar is Yang and represented by Gen Gua- the Yongest Son, and, its Earthly Branch is Yin, represented by Dui Gua- the  Youngest Daughter).

“八卦之象也。”

The images (and order) of the BaGua.

“故术家以岁主父母、月主兄弟、日主身及其妻、辰主所生之男女，盖取诸 此也。”

Thus, Year Pillar is mainly to do with one’s parents, Month Pillar with one’s siblings, Day Pillar with oneself and wife (spouse) and Hour Pillar with one’s off-springs.

“岁为根、月为枝，日为花，辰为实。”

Year is the root, Month is the branch, Day is the flower and Hour is the fruit.

“父母者，人之根也。”

Our parents is our root.

“兄弟者，同枝而生之者也。”

Our siblings are fellow branches which are borne from the same root.

“成人授室而生生之道具矣，故曰花。”

In adulthood, we come out of age, blossom and develop into flowers.

“育嗣有继而种类不穷矣，故曰实。”

From flowering, the fruits are borne.

“年主初岁，未离乎父母也。”

Year Pillar governs one’s early age as he/she is under the care of his/her parents.

“月主弱年，未分于兄弟也。”

Month Pillar covers one’s development years (弱年為年少;弱冠之年) where one’s growth and development are still in tandem with one’s siblings.

“日主强壮，授室而成家也。”

Day Pillar is of the age where one matures and is independent enough to start one’s family.

“辰主晚暮，传嗣而休老也。”

Hour Pillar governs one’s old age and descendants.

“其所取于乾坤六子者如此。”

The order and behavioural patterns of Qian-Kun family gua (BaGua).

Without a conceptual understanding of the above, it is difficult for one to achieve consistency in reading BaZi, and, thus create consistent results from Feng Shui.