紫微斗數 (Zi Wei Dou Shu/Purple Star Astrology) is a study from the 命 (Ming/Destiny) aspects of 五術 (Five Arts). It gives an insight into Predeterminism, a blueprint from the Heavens (33%) in the Cosmic Trinity of Life Aspiration. It is wrongly regarded by some as a study of Divination, which is not the case (Qi Men Dun Jia, Da Liu Ren, Tai Yi, etc are divinations). Also contrary to popular beliefs, there are no involvement with external influences and/or supernatural entities that some of the other destiny readings do involve in (utilizing spirits to gain insight to the past of the client). ZWDS itself is already a self contained dynamic system that can have detailed and specific insights to the past, present and future. It essentially is data analytics on 18-108 stars, 12 palaces and varied interactions involving the positions, brightness, elements, timing, birth years and transformation stars flying sequences as statistical comparative judgement. The only information of most crucial importance is the birthtime of the client down to the hour.
Unlike most other forms of fortune telling, the adept will only solely rely on giving definitive prognosis based on the information (depending on what level of understanding he has of this study) and the outcome should match up to 99% accuracy, all these done without the fraudulent practice of hot reading/cold reading, vague flowery metaphors, open ended ambiguity, Barnum statement, etc. The best prognosis should only have answers, instead of questions.
ZWDS is generally divided into two school of thoughts, largely the 四化象數派 “Flying Star” lineage that utilizes 18 stars and the 三合星辰派 “San He” lineage that utilizes about 30-108 stars. “Flying Star” lineage uses the flying power of the 4 Transformation to analyse and decode the destiny while the “San He” lineage uses stars groupings in triangle harmony formation as well as left and right flanking an direct opposite of zone to form an interpretation. Most modern practitioners combine the two to make a definitive analysis.
Another related method of destiny study is Four Pillars of Destiny 八字 (Bazi). Bazi is an aspect that is usually studied together with ZWDS to have a holistic analysis of life destiny but the two systems are fundamentally different. ZWDS is a 數 that calculates mathematical stars interactions in the Lunar calendar with a system of unbalanced energies over the set. The phenomenal 數 aspect is a heavy emphasis on the more I-Ching based Si Hua school. San He school has a almagation towards heavier usage of 氣. Bazi is a 氣 study that observes interactions of Yin and Yang Polarities of 5 Elements, 10 Heavenly Stems and 12 earthly branches within 8 Characters inside 4 Pillars based on the Solar calendar aiming to achieve balance of energies. ZWDS incorporated new moon day as 1st day of Lunar month, and it factors one leap year in every 4 years. Bazi is largely based on 365 days over 12 months with no leap year. In terms of pinpointing down to specific aspects of analysis, ZWDS is alot more dynamic and highly accurate.
While most practitioners of ZWDS claimed that there are no real astronomical relations of this form of astrology to the actual cosmos, actually, this art is based on a similar format used in Western and Hindu horary horoscopes with 12 houses format (and a 13th auxillary). The only difference is that ZWDS unlike other astrology have not undergone adaptation to precession of the equinoxes. 紫微 star is not fictitious. It is actually used as an axiom in α Draco in 2700 BC, traditionally used to track circumpolar time variation in solar shadow and stars movements by ancient Chinese sundial and armillary spheres. In modern times, the true north is getting very close to Polaris in Ursa Minor. There are alot of misconceptions from Chinese Metaphysics practitioners that Polaris is axiomatic, which is totally wrong. Many practitioners time adjusted ZWDS readings according to Lunar timing. This never takes into account of the precession. The concept of the Early Heaven is based on 先天 whereas the present Later Heaven is based on 後天. 先天後天 signifies pre and post-precession. The precession is in my opinion, the “Fall” (in biblical concept) of the current epoch. ZWDS’s Heavenly Template is set in 先天, and it should be based on actual timing of geological Chi (imprinted in the earlier system) specific to its locality. Henceforth in my opinion, and through personal empirical examinations down to the degrees of accuracy comparisons, it should be based on the actual time you are born (and the only timing adjustment to make is Daylight savings) in your own habitat, instead of the usually practised time adjustment to longitude 120E.
However, while the template is 先天 (Early Heaven/ predetermination), the subsequent events as the template turns into periodic phases are 後天 (After Heaven/ predetermination/free-will). The knowledge of the phases will allow the native to capitalise on the good and bad of the luck cycle. That in itself is free-will, the chances open to altering destiny. Life is from the causative Heaven, the impermanent Earth and the end effects that only Man can bring about.