WHAT IT IS

Zodiacal isopsephy is a method that finds the planet and zodiac of a name via its lexarithmos. In antiquity, when someone did not know their exact time of birth (very common), they used this method as a substitute for genethlialogy — instead of a horoscope, they calculated the planet of their name.

The operation is simple: calculate the lexarithmos of the name, divide by 7 and keep the remainder. This remainder gives you the planet. If you divide by 12, the remainder gives you the zodiac sign.

HISTORY & SOURCES

Hippolytus of Rome (3rd cent.) describes in Refutatio IV.14 the "Rule of Seven" alongside the "Rule of Nine" (onomatomancy). While the rule of 9 was used for comparing two names, the rule of 7 corresponded the number to a planet.

The planetary order follows the Ptolemaic sequence — from nearest to Earth to farthest: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn. It is the same order used in the Greek Magical Papyri (PGM) and the Hermetic tradition, and corresponds to the 7 vowels: Α, Ε, Η, Ι, Ο, Υ, Ω.

Vettius Valens (~150 AD) in Anthologies I describes in detail the characteristics of each planet — what qualities it gives to the person it "governs." Joel Kalvesmaki (Georgetown University) calls this method "zodiacal isopsephy."

Variation: in some sources, the lexarithmos of the name is added to the lexarithmos of the mother's name before division.

PLANETS (PTOLEMAIC ORDER)

1 — Moon ☽	Fertility, travel, emotions, changeability
2 — Mercury ☿	Intellect, communication, commerce, wit
3 — Venus ♀	Love, beauty, art, harmony, friendship
4 — Sun ☉	Authority, honor, mind, dignity, justice
5 — Mars ♂	Courage, leadership, strength, action, decisiveness
6 — Jupiter ♃	Justice, wealth, blessing, wisdom, freedom
7 — Saturn ♄	Discipline, patience, depth, stability

HOW IT WORKS

Name: ΛΟΓΟΣ
Step 1 — Calculate the lexarithmos:
Λ=30, Ο=70, Γ=3, Ο=70, Σ=200 → 30+70+3+70+200 = 373
Step 2 — Find the planet (remainder by 7):
373 ÷ 7 = 53 × 7 = 371, remainder 2
Remainder 2 → Mercury ☿ (intellect, communication, commerce)
Step 3 — Find the zodiac (remainder by 12):
373 ÷ 12 = 31 × 12 = 372, remainder 1
Remainder 1 → Aries ♈
ΛΟΓΟΣ is "governed" by Mercury (god of communication and speech) and belongs to Aries (beginning, initiative).

CONCLUSION

Zodiacal isopsephy was a practical tool when the exact time of birth was unknown. By dividing the lexarithmos by 7 and 12, we obtain the cosmic "coordinates" of a name — its ruling planet and zodiac sign.