Geomantic figures
The 16 geomantic figures are the primary symbols used in divinatory geomancy. Each geomantic figure represents a certain state of the world or the mind, and can be interpreted in various ways based upon the query put forth and the method used to generate the figures. When geomancy was introduced to Europe in the Middle Ages, the figures acquired astrological meanings and new forms of interpretation. The figures bear superficial resemblance to the ba gua, the eight trigrams used in the I Ching, a Chinese classic text.
Each of the figures is composed of four lines, each line containing either one or two points. Each line represents one of the four classical elements: from top to bottom, the lines represent fire, air, water, and earth. When a line has a single point, the element is said to be active; otherwise, with two points, the element is passive. Because there are four lines, and since each line can be either active or passive, there are 24, or 16, different figures. The different combinations of elements yields different representations or manifestations of the figure's energy.
Each figure can be said to have a ruling element, whereby that element's energy and manifestations correlates most closely to the figure itself. With the exception of Populus, the ruling element for each figure is always represented as active (a single point in the corresponding line). For figures with only one active element, that element by default is its ruling element; other combinations of active and passive elements require more introspection to assign rulerships. Populus, consisting of all passive lines, is ruled by Water by its nature of being entirely passive and taking on the reflective qualities of water whenever an outside force acts upon it.
While the elements just described are from the geomantic tradition, another set of elemental assignments are used based on the figures' astrological connections. These elements are assigned based on the zodiac sign of a given figure. The geomantic element is said to reflect the nature of a figure when viewed alone; the astrological element reflects its nature when acting with other figures.
Another classification of the geomantic figures involves their quality, which is either stable or mobile. The quality of a figure represents its duration of effect or motion, such that a figure with a stable quality will represent a long-term situation or that a certain object remains where it was left, while a mobile figure represents a transient effect upon the real world. In simple "yes or no" style divinations, stable figures indicate a positive answer, while mobile figures indicate a negative one.
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