Mutagens and flying stars

For: everyone. Code and the full method table are at the end of the page

Mutagens carry the most important dynamic information in Zi Wei Dou Shu. On a single chart they wire the static stars into a directed web of relationships.

The four mutagens

Mutagens come from the heavenly stem

Each heavenly stem assigns four fixed stars to Lu, Quan, Ke and Ji respectively. It is a lookup table:

Natal mutagens

When charting, the birth-year stem is looked up in the table above and the mutagen marks are stamped onto the corresponding stars. A chart carries exactly four natal mutagens — the mutable stars include Wenchang, Wenqu, Zuofu and Youbi alongside the fourteen major stars, and all four of those minor stars are always present, so the count never falls short.

Horoscope mutagens

Beyond the natal set, every horoscope level has mutagens of its own: the decadal uses its decadal palace stem, the yearly level uses the year's stem, and so on. They stack onto the same chart and are the main handle for reading a horoscope.

The four returned stars are always in the order Lu, Quan, Ke, Ji.

Flying stars

Palaces have heavenly stems too. Look a palace stem up in the mutagen table and you get the four stars that palace flies out; then see which palaces those four stars sit in. That is a flying star, and it is how the working relationships between palaces are described.

Self-mutagens

When a mutagen star flown out by a palace's own stem lands inside that same palace, it is a self-mutagen.

In a reading, a self-mutagen means force being spent or leaking inside the palace itself — a different character from flying into another palace.

In code

Reading the natal mutagens

chart = Astro().by_solar("2000-8-16", 2, "female", language="en-US")

for p in chart.palaces:
    for s in p.major_stars + p.minor_stars:
        if s.mutagen:
            print(f"{p.name} — {s.name} takes {s.mutagen}")

wealth — general takes B
children — sun takes A
friends — moon takes C
health — fortunate takes D

Reading horoscope mutagens

h = chart.horoscope("2024-10-1", 0)
print(h.decadal.mutagen)   # the four stars of the decadal mutagens
print(h.yearly.mutagen)    # the four stars of the yearly mutagens

['sun', 'general', 'moon', 'fortunate']
['judge', 'rebel', 'general', 'sun']

For predicates use the key form h.yearly.mutagen_star_keys — the mutated stars' star keys, independent of translation.

Asking whether a palace holds a mutagen

soul.has_mutagen(Mutagen.LU)
soul.not_have_mutagen(Mutagen.JI)

Flying-star predicates

let wealth = astrolabe.palace(Palace::Wealth).unwrap();

// does the Ji flown out by the Wealth palace's stem land in the Soul palace?
wealth.flies_to(Palace::Soul, &[Mutagen::Ji]);

soul.flies_one_of_to(PalaceName.WEALTH, [Mutagen.LU, Mutagen.QUAN])
soul.not_fly_to(0, Mutagen.JI)

places = soul.mutaged_places()   # which palace each of Lu/Quan/Ke/Ji flew into; length 4

Self-mutagen predicates

soul.self_mutaged(&[Mutagen::Lu]);   // does the Soul palace self-mutate Lu
soul.self_mutaged_one_of(&[]);       // any self-mutagen at all
soul.not_self_mutaged(&[]);          // none of the four

Passing an empty list to self_mutaged_one_of or not_self_mutaged checks all four mutagens; pass a subset to check only those.

The full method list

A palace also carries a mutagen_star_keys field, giving directly the keys of the four stars its stem mutates, in the order Lu, Quan, Ke, Ji; it follows a custom mutagen table when one is set.

For mutagen predicates across the surrounded palaces, see Surrounded palaces.