Most standard texts on astrology, from the more ancient to the recent, western or Indian begin with a description of the signs, planets and houses. Indian texts often add a description of the nakshatra or lunar mansions. Quickly an example is introduced in which the combination of the three for a particular time is presented. This may be called a figure, a diagram, a chart, a horoscope, a chakra, a wheel or in a specialised form, cosmogram. Some texts provide a description of the, let us call it chart. Other texts don’t. Usually the student adopts what is presented, and later, what seems more convenient. Generally no further thought is given to the matter. So the answer to the question whether the choice of round or square is through convention or tradition can be answered that it is generally through convention. The form first encountered or a software default seems to decide the issue. Yet, the chart is a potent astrological image. And in my opinion greater care should be given in its choice. In fact, depending on the focus, the appropriate form should be used! Do you know what the twelve divisions in your favourite chart form represent? Are they signs? Constellations? Houses?
There is also the other side of the question. Is there such a thing as a traditional chart? Modern western astrology has adopted a round chart form. But is this the traditional form? O. Neugebauer and H. B. van Housen in their book on Greek Horoscopes include a drawing after the Oxyrhynchus 235 papyrus which shows a lopsided, wobbly, hand drawn circle divided by a horizontal and intersecting vertical line that represent the axis of the horizon and the zenith. It is a chart for a person born between 15 and 37 AD. They also say that such diagrams are very rare and that only later in Byzantine codices do diagrams appear with greater frequency. There, however, various forms of the square chart are used. It seems that up to the 19th century the square chart was the dominant form in the West. It is still the dominant form in India.
The chart is a map of the heavens for a certain moment of time at a particular location. It can be for a person, an event or even for the moment of a question. Just how the heavens are depicted remains to be explored. The planets can be mapped against the constellations or using the tropical zodiac. This is also where we have to be absolutely sure what is meant by ‘sign’ or in Indian astrology ‘rasi.’ We’ll explore this later in more detail.
For the moment location is of interest to us. It can be described as the intersection of two imaginary great circles known as the longitude and latitude or as being situated in an area between two longitudinal and latitudinal sections which we can call a quadrant. In fact one of the few situations where circles may form a square is in mapping in two dimensions. Keep this in mind when we explore the construction of square and round charts in the next articles.