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Ptolemy's Significance
Ptolemy's Cosmos
Planetary Humours
Notes & References
About the Author

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The Life & Work of Ptolemy, by Deborah Houlding

Claudius Ptolemaeus, better known as Ptolemy, lived and worked in the middle of the 2nd century AD. His astrological textbook - the Tetrabiblos - became the standard bearer for subsequent generations. He has been been referred to as 'the most important single figure in the history of astrology, and one of the most important in the history of astronomy'. [1]

In the history of science there can be few names more illustrious than Ptolemy's but in view of his reputation very little is known about his life. Research into his personal circumstances has proved fruitless apart from a fairly well-established opinion that he was born at Ptolemais in Egypt sometime around the year 100 AD, died around the age of 78, and worked within the precincts of Alexandria on the Nile. A study of his texts reveals an extensive knowledge of philosophy, mathematics, geography, astronomy and astrology. A proficiency and interest in music is also suggested in some of his minor works, in keeping with the Platonic belief that astronomy and music are twin sciences, linked by the Pythagorean philosophy of the harmony of the spheres.

Modern astrologers remember Ptolemy as the author of one of the oldest complete manuals of astrology, - the Tetrabiblos (Greek) or Quadrapartitium (Latin) meaning 'Four Books'. Although we know Ptolemy did not invent his methods of astrology we recognise his contribution as being one of orchestrating the mass of Eastern star lore into an organized and reasoned exposition. The Tetrabiblos offered a detailed explanation of the philosophical framework of astrology, enabling its practitioners to answer critics on scientific as well as religious grounds. His expert defence of the validity of astrology put forward arguments that were so sound and pertinent to his day that Lynn Thorndike, in his History of Magic and Experimental Science, writes:

Only the opponents of astrology appear to have remained ignorant of the 'Tetrabiblos', continuing to make criticisms of the art which do not apply to Ptolemy's presentation of it or which had been specifically answered by him. Thus Sextus Empiricus, attacking astrology about 200 AD, does not mention the Tetrabiblos and some of the Christian critics of astrology apparently had not read it. ([2] )

Ptolemy achieved his reputation through his astronomical accomplishment. Working from his observatory he catalogued over 1000 stars (300 of which were newly discovered), created the first viable theory of the refraction of light, discussed the dimensions of the planets with considerable precision and made many other general advances. His astronomical treatise, the the Almagest (from the Arabic phrase Al Majesti, 'The Greatest') is a complete manuscript of the astronomical knowledge of the classical world. In this he discloses his vision of the universe -- a view which was adopted and applied by his successors for many centuries throughout medieval Europe.

Ptolemy described a spherical world, suspended freely in the centre of the universe, around which revolved the Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn respectively. Beyond the orbit of Saturn lay a solid exterior to the universe, to which the fixed stars were attached. Most of this is based upon Aristotelian philosophy, which decreed that planets move in perfect circles in constant and uniform motion. In order to make observation agree, and to explain the phenomenon of retrograde motion, Ptolemy developed the theory that planets move in circular 'epicycles' along their orbits. As errors in his system were brought to light, more epicycles were added to correct them.

The Ptolemaic universe

Although the Ptolemaic scheme may appear cumbersome compared to the modern understanding of the universe, the reason that it dominated science for so long was that it actually worked. With the detailed information that Ptolemy had to work from, he was able to use the scheme as a basis for monitoring and predicting the positions of the planets with great accuracy. Although his central measuring point was different from our own, for all practical purposes, it was just as reliable. In his 'general preliminary discussion', in Book 1, chapter 2 of the Almagest, Ptolemy outlined his position that the Earth is in the middle of the heavens 'with regard to the senses' - a key phrase to be borne in mind, since the ability to maintain the geocentric viewpoint, measuring the planets as they appear from the Earth, was an important issue for the wider philosophical structure of the classical world.

As a leading intellectual of his day, Ptolemy's patronage and approval of astrology added to its academic respectability. By preserving its credibility as a science as well as an art, he safeguarded its practice during the medieval period when many other occult studies were persecuted on religious grounds. He spoke of astrology with authority and lucidity, establishing the Tetrabiblos as the definitive reference for astrological students. It was used extensively by Arabic scholars, who regarded Ptolemy as the final word on the subject, and later by European ones when it was translated back into Latin in the 12th century.

The Tetrabiblos has been referred to as 'the surrender of science' ([3] ), an unfair statement since Ptolemy reveals no interest in magic, superstition or ideas which fall beyond the realm of reason. He adheres strictly to the current scientific views of his era. Most of his philosophy rests upon the belief that planetary influences derive from the planets' relationship with the Sun (the source of heat and light) and the Earth (the source of moisture). In this way the Moon is regarded as a 'cool and moist' planet because it lacks the warmth of the Sun and lies in the proximity of the Earth. Saturn is 'cold and dry' because it is furthest from the warmth of the Sun and, again, from the moisture of the Earth. Planetary characteristics are defined by these humoural temperaments where, as in nature, warmth and moisture promote health and vitality whilst cold and dryness are conducive to decay. Hence Saturn becomes the principal agent of destruction and death; the 'Greater Malefic'.

[ Roll over the image to view the basis of Ptolemy's planetary humours ]

Through this hypothesis Ptolemy explains how the constant movement of the planets creates an ever-changing atmosphere to which all the Earth's creatures are sensitive. Just as two similar seeds grow differently as a result of their environment, so is each soul affected by the celestial atmosphere at the time of its birth. In the principle of sympathy and antipathy the aspects and movement of the stars continue to produce favourable or injurious conditions -determined by the individual's personal disposition.

To Ptolemy, therefore, astrology is a scientific study because it operates according to natural law. Although he maintains the importance of the angles of a chart, the Tetrabiblos shows a noticeable lack of interest in the houses, whilst other elements of astrology were considered to be completely unworthy of mention, either because they were too unscientific, too reminiscent of fortune telling, or defied any kind of rational explanation:

... as for the nonsense on which many waste their labour and of which not even a plausible account can be given, this we shall dismiss in favour of the primary natural causes. What, however, admits of prediction we shall investigate, not by means of lots and numbers of which no reasonable explanation can be given, but merely through the science of the aspects of the stars to the places with which they have familiarity. ([4] )

Perhaps in this attitude we find the main drawback of Ptolemy's work. His unwillingness to accept the concepts of astrology that are infused with symbolism rather than pure reason not only leaves his work a little dry in places but also denies the use of astrology as a mystical art. The paradox is that there are passages in the Tetrabiblos where he speaks of astrology being divine, telling us to appreciate its beauty, whilst the following short passage, obviously penned in a more relaxed and lyrical mood, reveals that Ptolemy clearly experienced some kind of spiritual or idealistic motivation which inspired the excellent standard of his work:

I know that I am mortal, the creature of one day. But when I explore the winding courses of the stars I no longer touch with my feet the Earth: I am standing near Zeus himself drinking my fill of Ambrosia, the food of the Gods. ([5] )

 learn more about Ptolemy's use of houses

Notes & References:
  1 ] Campion, N., An Introduction to the History of Astrology, p.35; Institute For the Study of Cycles in World Affairs.
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  2 ] Thorndike, L., The History of Magic and Experimental Science, p.116; Columbia University Press
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  3 ] Bouché-Leclercq, AG., Rev. Hist., LXV, p257, note 3 - "c'est la capitulation de la science"
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  4 ] Ptolemy, Tetrabiblos, III.3, p.237; Harvard Heinemann ed. (Trans. F.E. Robbins); Loeb Classical Library
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  5 ] Ptolemy, Anthologia Palatina, 9.577 348
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Deborah HouldingDeborah Houlding is the web mistress of the Skyscript site. The past editor of The Traditional Astrologer magazine, and author of The Houses: Temples of the Sky, her articles feature regularly in astrological journals. She has a particular interest in researching the origin and development of astrological technique and as a consulting astrologer specialises in horary. She is the principal of the STA school of traditional horary astrology, which offers courses by correspondence and intensive residential seminars.
© Deborah Houlding.
This article was first published in The Traditional Astrologer Magazine, Issue 1, June 1993, pp.3-5.
Reproduced online 2003.