tropical zodiac2nd century CE, transmitted through Arabic and Latin commentary15 rules
Hellenistic (Ptolemaic)
The system set out in Ptolemy’s Tetrabiblos, which grounds planetary signification in the four elemental qualities and treats the zodiac as measured from the equinox. It is the transmission route for much later Western practice, and it is not identical to any of them.
Chart types · natal · mundane
Epistemic status
Every rule below is recorded as documented interpretive tradition with no empirical validation. The provenance badge states how faithfully the record represents its source; it is not a measure of whether the rule is true. Prohibited uses: medical diagnosis, prognosis, or treatment decisions; legal conclusions or advice; investment, trading, or other financial decisions; predictions of death, disaster, or pregnancy outcomes; claims that a chart determines personality, capability, or behaviour; guarantees about future events; high-stakes decisions taken on astrological grounds alone; employment, lending, insurance, or housing decisions about a person.
The tradition classes Jupiter and Venus as benefic, deriving the classification from a predominance of the heat and moisture held to be nutritive.
Chart conditions
subject.identifiers — Jupiter or Venus is present in the chart.
Source passages
“Therefore, two of the planets, on account of their temperate quality, and because heat and moisture are predominant in them, are considered by the ancients as benefic, or causers of good: these are Jupiter and Venus.”
Later traditions treat benefic and malefic as contextual rather than fixed, conditioning the classification on sect, dignity, and house placement.
Boundary: A classification internal to the tradition’s elemental physics. The underlying qualitative theory of heat, cold, moisture, and dryness is not a description of the planets as understood by astronomy.
The tradition classes Saturn and Mars as malefic, attributing the classification to an excess of cold in Saturn and an excess of dryness in Mars.
Chart conditions
subject.identifiers — Saturn or Mars is present in the chart.
Source passages
“But Saturn and Mars are esteemed of a contrary nature, and malefic, or causers of evil: the first from his excess of cold, the other from his excess of dryness.”
The tradition treats the Sun and Mercury as of common influence, taking their effect from the planets they are configured with rather than from a fixed nature.
Chart conditions
subject.identifiers — The Sun or Mercury is present in the chart.
Source passages
“The Sun and Mercury are deemed of common influence, and productive either of good or evil in unison with whatever planets they may be connected with.”
The gendered classification of planets is rejected or reinterpreted as symbolic polarity across most contemporary practice.
Boundary: A 2nd-century classification recorded for historical accuracy. It reflects the gender assumptions of its period, carries no evidential weight, and must not be applied to any person or used to infer anything about sex or gender.
The tradition assigns the Sun, Saturn, Jupiter, and Mars to the masculine category, and treats Mercury as common to both because it produces dryness and moisture in equal ratio.
Chart conditions
subject.identifiers — The Sun, Saturn, Jupiter, or Mars is present in the chart.
Source passages
“The Sun, Saturn, Jupiter, and Mars are called masculine. Mercury is common to both genders, because at certain times he produces dryness, and at others moisture, and performs each in an equal ratio.”
The gendered classification of planets is rejected or reinterpreted as symbolic polarity across most contemporary practice.
Boundary: A 2nd-century classification recorded for historical accuracy. It reflects the gender assumptions of its period, carries no evidential weight, and must not be applied to any person or used to infer anything about sex or gender.
Unvalidated traditionRestates sourcescope of nativitiesnatal
The tradition names the study of individual nativities Genethlialogy and separates it from the general or mundane inquiry treated earlier in the work.
Chart conditions
time.utcInstant — A birth moment is given.
Source passages
“The foreknowledge of these particular events is called Genethlialogy, or the science of Nativities.”
Boundary: A definition of the tradition’s own scope. It records how the text divides its subject and asserts nothing about what a birth chart can show.
Unvalidated traditionRestates sourceorder of judgementnatal
The tradition holds that the question of the duration of life is taken up before all other post-natal questions, on the reasoning that other predictions are moot without it.
Chart conditions
time.utcInstant — A birth moment is given.
Source passages
“Of all events whatsoever, which take place after birth, the most essential is the continuance of life.”
Contemporary practice generally abandons length-of-life technique entirely, on both evidential and ethical grounds.
Boundary: Recorded as the structure of a historical text. Maha does not publish length-of-life judgements, and no report may generate one: see the prohibited uses attached to this layer.
The tradition restricts the prorogatory places to a defined set, beginning with the region of the ascendant running from five degrees above the horizon to twenty-five degrees below it.
Chart conditions
coordinates.values — Ecliptic longitudes of the angles are computed.
observer.position — Observer latitude is known, since the angles depend on it.
Source passages
“These several places are the sign on the angle of the ascendant, from the fifth degree above the horizon, to the twenty-fifth degree below it.”
The set of prorogatory places and their ordering differ between Ptolemy and other Hellenistic authors, and the technique is not used in most modern practice.
Boundary: A technical specification internal to the tradition. It is reproducible as geometry from the fact layer; that reproducibility says nothing about whether the technique means anything.
The tradition holds that Saturn oriental gives a yellowish complexion, black curled hair, a broad chest, and proportionate size.
Chart conditions
coordinates.values — Saturn holds dominion and is oriental to the Sun.
Source passages
“Saturn, when oriental, acts on the personal figure by producing a yellowish complexion and a good constitution; with black and curled hair, a broad and stout chest, eyes of ordinary quality, and a proportionate size of body.”
Physical-description technique is abandoned in most contemporary practice.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.
The tradition holds that Jupiter oriental gives a fair and clear complexion, moderate hair, large eyes, and dignified stature.
Chart conditions
coordinates.values — Jupiter holds dominion and is oriental to the Sun.
Source passages
“Jupiter ruling, when oriental, makes the person white or fair, with a clear complexion, moderate growth of hair, and large eyes, and of good and dignified stature.”
Physical-description technique is abandoned in most contemporary practice.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.
The tradition holds that Mars ascending gives ruddiness, large size, blue or grey eyes, and a sturdy figure.
Chart conditions
coordinates.values — Mars holds dominion and is ascending.
Source passages
“Mars, ascending, gives a fair ruddiness to the person, with large size, a healthy constitution, blue or grey eyes, a sturdy figure, and a moderate growth of hair.”
Physical-description technique is abandoned in most contemporary practice.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.
The tradition holds that Venus works as Jupiter does but more gracefully, and is said to make the eyes beautiful and azure.
Chart conditions
coordinates.values — Venus holds dominion over the form.
Source passages
“Venus operates in a manner similar to that of Jupiter, but, at the same time, more becomingly and more gracefully. She also peculiarly makes the eyes beautiful, and renders them of an azure tint.”
Physical-description technique is abandoned in most contemporary practice.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.
The tradition holds that Mercury oriental gives a yellowish complexion, proportionate and well-shaped stature, small eyes, and moderate hair.
Chart conditions
coordinates.values — Mercury holds dominion and is oriental to the Sun.
Source passages
“Mercury, when oriental, makes the personal figure of a yellowish complexion, and of stature proportionate and well shaped, with small eyes and a moderate growth of hair.”
Physical-description technique is abandoned in most contemporary practice.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.
Medical application of astrology is rejected by contemporary medicine and by most contemporary astrological practice.
Boundary: Recorded as historical doctrine only. This rule must never contribute to a health statement of any kind: medical diagnosis, prognosis, and treatment are prohibited uses of this layer without exception.
Unvalidated traditionRestates sourcequality of mindnatal
The tradition assigns the intellectual qualities to the situation of Mercury, and the sensitive faculties independent of reason to the Moon and the stars configured with her.
Chart conditions
coordinates.values — The position of Mercury is computed.
coordinates.values — The position of the Moon and its applications and separations are computed.
Source passages
“Of the spiritual qualities, however, all those which are national and intellectual are contemplated by the situation of Mercury.”
Transcription note: The cited Gutenberg edition reads “national”. Other printings of the Ashmand translation read “rational”, which the surrounding argument supports. Transcribed as it appears in the cited edition rather than silently corrected.
Disagreements
The division of mind between two significators is handled differently across Hellenistic authors, and psychological astrology reframes it as symbolic rather than causal.
Boundary: Recorded as historical doctrine of the named tradition. There is no evidence that planetary position corresponds to physical appearance or mental character, and this rule must not be used to describe, assess, or make decisions about any person.