Geomancy is a method of divination that interprets markings on the ground, or how handfuls of soil, dirt or sand land when someone tosses them. In Africa one traditional form of geomancy consists of throwing handfuls of dirt in the air and observing how the dirt falls. It can also involve a mouse as the agent of the earth spirit. In China, the diviner may enter a trance and make markings on the ground that are interpreted by an associate, often a young boy.
In Korea, this tradition was popularized in the ninth century by the Buddhist monk Toson. In Korea, Geomancy takes the form of interpreting the topography of the land to determine future events and or the strength of a dynasty or particular family. Therefore, not only were location and land forms important, but the topography could shift causing disfavor and the need to relocate. The idea is still accepted in many South East Asian societies today, although with reduced force.
Geomancy in western tradition requires no instruments and no calculations; it is based solely on the human propensity for pattern recognition. Modern methods of geomancy include, in addition to the traditional pen and paper or sand methods, using geomancy cards, random number generators, or thrown objects.
Diviners in medieval Europe used parchment or paper for drawing the dots of geomancy but they followed the traditional direction of notation, right to left, for recording the dots. Western occultism still defines geomantic technique as marking sixteen lines of points in sand or soil with a wand or on a sheet of paper. The geomancer counts the number of points made in each line and produces either a single dot for an odd number of points, or two dots for an even number, for each line. The pattern of dots produced by the first to fourth lines are known as a figure.
Those four derived figures are entered into two charts, known as the Shield and House charts, and through binary processes form the seed of the figures that fill the whole charts. The charts are subsequently analyzed and interpreted by the geomancer to find solutions, options, and responses to the problem quesited, along with general information about the querent, providing an all-round reading into the querent’s life.
This form of geomancy is easy to learn and easy to perform. Once practiced by commoners and rulers alike, it was one of the most popular forms of divination throughout Classical antiquity and the Middle Ages. Books and treatises on geomancy were published up until the 17th century, when the geomancy generally stopped being practiced.
Mathematician Ron Eglash, while studying fractal structures in African culture, identified a binary recursive process that used self similarity to create a random number generator from an initial set of lines that a geomancer draws on the ground. This technique was brought to Europe by way of North African Islamic mystics. It is very likely that these mystics had previously obtained the approach from traditional African societies by way of interactions between the West African and North African trade.
Unlike the practices in many other regions such as the Middle East and China, which utilized base 10 numeric systems, the base 2 system utilized in geomancy had long been widely applied in sub-Saharan Africa. Partly inspired by the geomantic technique, Gottfried Leibniz, a German mathematician, developed the binary code theory, which later was the base for boolean algebra in modern computers, although it should be noted that certain boolean systems such as that used by SQL are in fact based upon three-valued logic.