Hellenistic Astrology · Sect

Sect Evaluator

Day birth or night birth? Is each planet in its own sect or in the contrary one? How is its benefic/malefic nature modulated?

What Is Sect (Hairesis)?

Sect (Greek hairesis, "preference / faction") is the foundational division of Hellenistic astrology: was the birth diurnal or nocturnal? If the Sun is above the horizon the chart is diurnal; if below, nocturnal. The seven classical planets divide into two teams: the diurnal team (Sun, Jupiter, Saturn) and the nocturnal team (Moon, Venus, Mars). Mercury can take either side, eastern of the Sun (rising before it) makes it diurnal, western (rising after it) nocturnal.

When a planet is in its own sect (e.g. Jupiter in a day chart), it is in sect; its strength rises, its benefic nature expands, its malefic nature softens. When out of sect (e.g. Mars in a day chart) its action sharpens and tends toward unexpected harm.

Enter Birth Information

Local time, 24-hour format
The sign the Sun was in on the birth date
Houses 7–12 above horizon = diurnal · 1–6 below = nocturnal
Is Mercury a morning star or an evening star?

Primary and Secondary Sources

  • Vettius Valens, Anthologies Books II–IV (2nd c. CE), sect doctrine and application.
  • Ptolemy, Tetrabiblos III.4–5, theoretical framework for the diurnal/nocturnal division.
  • Dorotheus of Sidon, Carmen Astrologicum Book I (1st c. CE), sect and houses.
  • Paulus Alexandrinus, Eisagogika §6 (4th c. CE), definition of hairesis.
  • Brennan, C. Hellenistic Astrology: The Study of Fate and Fortune, Amor Fati, 2017, sect chapter.
  • Greenbaum, D. The Daimon in Hellenistic Astrology, Brill, 2016, sect and daimon.

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Frequently Asked Questions

About the doctrine of sect (hairesis)

What exactly is sect (hairesis)?

Sect is the foundational Hellenistic distinction that asks whether, at the moment of birth, the Sun is above the horizon (diurnal) or below it (nocturnal). Hairesis in Greek means "preference" or "faction." The seven classical planets split into two teams: the diurnal team (Sun–Jupiter–Saturn) and the nocturnal team (Moon–Venus–Mars). Mercury can take either side.

What changes when a planet is "in sect"?

A planet in sect operates in the natural condition of its own team. A benefic (Jupiter, Venus) in sect produces stronger, more generous outcomes; a malefic (Mars, Saturn) in sect has its harm contained and acts in a corrective, instructive way. A malefic out of sect, by contrast, brings sharper, more unexpected disruptions.

What is the sect leader?

In a day chart the Sun is the sect leader; in a night chart, the Moon. It is the primary luminary of the chart and a key indicator of daimon and character. Vettius Valens treats it with special weight as the chart's "light-giver."

Why is Mars considered problematic in a day chart?

Mars is the malefic of the nocturnal team; in a night chart it is in its own team and softens. In a day chart it is out of sect; its hot, destructive nature is not balanced and it tends to release themes of conflict, accident and sudden anger more sharply. The reverse holds for Saturn: Saturn is harsher in night charts and more "instructive" by day.

Which sect does Mercury belong to?

Mercury is the "common" planet; its sect is not fixed. If Mercury rises before the Sun (oriental, morning star), it joins the diurnal team; if it rises after the Sun (occidental, evening star), the nocturnal team. In practice you check its ecliptic position relative to the Sun.

Why is sect little-known in modern astrology?

Sect was a central concept in Hellenistic and medieval Arabic astrology; it was largely lost in transmission to the Latin West. 20th-century modern astrology mostly did not use it. Project Hindsight translations (1990s–2000s) and Chris Brennan's 2017 work brought sect back into common use. With the revival of classical techniques it is once again a standard analytic layer.