It is fair to say that Claudius Ptolemy made the single greatest contribution to the transmission and preservation of astrological and astronomical knowledge of the Classical and Ancient world. No study of Traditional Astrology can ignore the importance and influence of this encyclopaedic work. It speaks not only of the stars, but also of a distinct cosmology that prevailed until the 18th century. Ironically, it is easy to jeer at someone who thinks the earth is the cosmic centre and refers to it as the sublunary sphere. However, our current knowledge tells us that the Universe is infinite, as far as we know. It seems to me that in an infinite universe, any given point must be the centre. Sometimes scientists are not so scientific. The fact is, it still applies to us for our purposes.

In practical terms, the Moon does have the most immediate effect on the Earth which is, after all, our point of reference. She turns the tides, influences the vegetative growth and menstrual cycles. In fact, she influences the weather itself.

What has become known as the Ptolemaic Universe, consisted of concentric circles emanating from Earth to the eighth sphere of the Fixed Stars, also known as the Empyrean. This cosmology is as spiritual as it is physical. It is a decidedly moral cosmology. No apologies are made for political incorrectness.

Ptolemy was first and foremost an anthologist. This knowledge came to him from Egypt, Greece, Chaldea, Babylonia and beyond. More to the point, he was in the enviable position of being in Alexandria during the peak of its eminence. Alexandria was in intellectual and spiritual foment. Ptolemy is clearly drawing from a wide range of sources in Tetrabiblos. His articulated cosmology has become known by his name. Whatever your thoughts on the status of Ptolemy, he remains required reading for anyone interested in the history of the celestial arts. His influence on Renaissance astrologers was profound in and of itself.