Essential dignity is a historical language for a planet’s relationship to a zodiacal location. The word “house” in Tetrabiblos I.17 means a planet’s zodiacal domicile, not a numbered place in a birth chart. This guide follows one explicit source convention so a reader can reproduce the lookup.
Five questions to ask of a chart degree
- Domicile: whose sign is this? The Sun rules Leo, Moon Cancer, Mercury Gemini and Virgo, Venus Taurus and Libra, Mars Aries and Scorpio, Jupiter Sagittarius and Pisces, and Saturn Capricorn and Aquarius.
- Exaltation: Ptolemy assigns Sun to Aries, Moon Taurus, Mercury Virgo, Venus Pisces, Mars Capricorn, Jupiter Cancer, and Saturn Libra. The opposite sign is the traditional fall.
- Triplicity: group the sign with two signs of its element. In Ptolemy’s account, a day and a night chart can have different leading rulers. This is the only field in the lookup changed by the sect choice.
- Bound or term: each sign is divided into five unequal stretches assigned to the five non-luminary planets. Select by the degree within the sign, starting at zero. At a boundary the new ruler begins.
- Opposite domicile: the sign opposite one of a planet’s domiciles is its traditional detriment. A planet can have a detriment or fall flag while also holding a minor dignity at that precise degree; the categories are displayed separately.
Day and night triplicity rulers used here
| Signs | Day | Night | Additional ruler |
|---|---|---|---|
| Aries · Leo · Sagittarius | Sun | Jupiter | — |
| Taurus · Virgo · Capricorn | Venus | Moon | — |
| Gemini · Libra · Aquarius | Saturn | Mercury | — |
| Cancer · Scorpio · Pisces | Venus | Moon | Mars in both |
The water arrangement follows Tetrabiblos I.18, which names Mars with Venus by day and the Moon by night. Other authors organize water differently. The table gives a transparent convention, not a universal one.
Egyptian bounds by sign and degree
Ptolemy prints this “commonly accepted” Egyptian table in I.20, then discusses another ancient manuscript arrangement. The lookup uses the printed common table. Each row totals 30° and the right edge belongs to the next segment.
| Sign | First | Second | Third | Fourth | Fifth |
|---|---|---|---|---|---|
| Aries | Jupiter0°–<6° | Venus6°–<12° | Mercury12°–<20° | Mars20°–<25° | Saturn25°–<30° |
| Taurus | Venus0°–<8° | Mercury8°–<14° | Jupiter14°–<22° | Saturn22°–<27° | Mars27°–<30° |
| Gemini | Mercury0°–<6° | Jupiter6°–<12° | Venus12°–<17° | Mars17°–<24° | Saturn24°–<30° |
| Cancer | Mars0°–<7° | Venus7°–<13° | Mercury13°–<19° | Jupiter19°–<26° | Saturn26°–<30° |
| Leo | Jupiter0°–<6° | Venus6°–<11° | Saturn11°–<18° | Mercury18°–<24° | Mars24°–<30° |
| Virgo | Mercury0°–<7° | Venus7°–<17° | Jupiter17°–<21° | Mars21°–<28° | Saturn28°–<30° |
| Libra | Saturn0°–<6° | Mercury6°–<14° | Jupiter14°–<21° | Venus21°–<28° | Mars28°–<30° |
| Scorpio | Mars0°–<7° | Venus7°–<11° | Mercury11°–<19° | Jupiter19°–<24° | Saturn24°–<30° |
| Sagittarius | Jupiter0°–<12° | Venus12°–<17° | Mercury17°–<21° | Saturn21°–<26° | Mars26°–<30° |
| Capricorn | Mercury0°–<7° | Jupiter7°–<14° | Venus14°–<22° | Saturn22°–<26° | Mars26°–<30° |
| Aquarius | Mercury0°–<7° | Venus7°–<13° | Jupiter13°–<20° | Mars20°–<25° | Saturn25°–<30° |
| Pisces | Venus0°–<12° | Jupiter12°–<16° | Mercury16°–<19° | Mars19°–<28° | Saturn28°–<30° |
Worked example: 6° Aries
Aries belongs to Mars by domicile and the Sun by exaltation. In a day chart its leading triplicity ruler is the Sun; in a night chart it is Jupiter. The Egyptian bound from 0° up to, but not including, 6° Aries belongs to Jupiter. Exactly 6° starts Venus’s bound, which lasts up to 12°. A Mars at 6° Aries is in domicile; it is not the bound ruler at that degree. Check another degree in the calculator.
Source and limits
The data is transcribed from Ptolemy, Tetrabiblos Book I, chapters 17–20, with the chapter 20 Egyptian table checked row by row. The lookup omits Chaldean decans or “faces”: Ptolemy’s later phrase “proper face” in I.23 describes a different planetary relationship. Mixing those meanings into one numerical score would hide the source distinction. Chart sect is an input because a zodiacal longitude alone does not reveal whether the Sun was above the horizon. This reference does not assess chart strength, outcomes, health, or character.
For a complete chart, calculate the birth chart and verify the source time and local horizon before choosing sect. For a chart without a reliable birth time, compare both day and night results instead of guessing.