2. Representation of the Skies and the Astrological Chart

Abstract

In Medieval and Renaissance astrology, the sky at any given moment in time is represented by a figure made up of three squares, inscribed one within the other. In the central square are written the name, along with the date, the hour and the place. The twelve equilateral triangles which circumscribe the central square divide the diurnal apparent motion of celestial bodies around the Earth into twelve parts. These are the houses, (domus); and each, within a given period, has its own particular force and quality. The graphic representation of the thema coeli (astral chart) is modelled on the diurnal motion of the celestial bodies, be they planets or fixed stars: they rise in the East, passing through the first house, culminating in the tenth. In their rotation, the celestial bodies do not go through the zodiac, but are transported from the primum mobile along parallel lines to the equator. Keywords: celestial bodies; Medieval astrology; primum mobile ; Renaissance astrology; thema coeli