Part of Fortune
Part of Fortune
The Part of Fortune (or Lot of Fortune) is calculated using the Sun, Moon, and Ascendant. It represents a point of potential happiness or success when integrated consciously.
To find its placement, astrologers use different formulas depending on whether the chart is diurnal or nocturnal. Once located, the sign and house of the Part of Fortune can show where you may experience ease or prosperity through aligning with your natural gifts.
Note:
This file is an original educational summary for the Astrology Arith(m)etic project. It does not reproduce proprietary text.
🧮 Formula
- Day chart (Sun in houses 7–12, above the horizon): Fortune = ASC + Moon − Sun
- Night chart (Sun in houses 1–6): Fortune = ASC + Sun − Moon
- Spirit is the mirror image (day: ASC + Sun − Moon).
Worked arithmetic (day chart): ASC 15° Leo (135°), Sun 10° Gemini (70°), Moon 25° Libra (205°) → 135 + 205 − 70 = 270° = 0° Capricorn.
Vault entries: Part of Fortune · Part of Spirit
Sources (study summary)
- Vettius Valens, Anthologies (2nd c. CE), Book II — Lot of Fortune/Spirit reversal by sect (trans. M. Riley, free PDF: https://www.csus.edu/indiv/r/rileymd/Vettius%20Valens%20entire.pdf)
- Claudius Ptolemy, Tetrabiblos (2nd c. CE), Book I — trans. F. E. Robbins, Loeb Classical Library 435 (1940), public-domain text at LacusCurtius: https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Ptolemy/Tetrabiblos/home.html
- Chris Brennan, Hellenistic Astrology: The Study of Fate and Fortune (Amor Fati, 2017) — house names, planetary joys, lots, sect