Geomancy is a 9th-century algorithmic divination system originating in the Arab world, using 16 figures composed of single or double dots arranged in four rows. It's arguably the most mathematical of all classical divination systems — a fully deterministic algorithm that generates a complete "shield chart" from four random inputs.
The 16 Figures
Each geomantic figure is a stack of four rows, each row containing one dot (active/odd) or two dots (passive/even). With 2⁴ = 16 possible combinations, you get figures like:
- Via (The Way) — four single dots, pure movement
- Populus (The People) — four double dots, pure receptivity
- Fortuna Major (Greater Fortune) — the most favorable figure
- Cauda Draconis (Dragon's Tail) — endings and departure
The Shield Chart
You generate four "Mother" figures randomly (traditionally by making random marks in sand — hence "geo-mancy," earth-divination). From these four, the system algorithmically derives four "Daughters," four "Nieces," two "Witnesses," a "Judge," and a "Reconciler." Twelve of these figures map to astrological houses, creating a complete reading from four random seeds.
This is what makes geomancy remarkable: it's a compression algorithm for divination. Four inputs expand into a full astrological chart. Chaos Tarot implements the complete shield chart with interactive visualization.