Ptolemy Wherefore art Thou Ptolemy*

For the ‘Year of Astronomy’ I have set myself the task of not only brushing up on my astronomical skills but also to tackle the shared icon of Astronomy and Astrology. The Almagest. I have chosen the translation by G.J. Toomer so that I can quote relevant passages without having to translate. The foreword to the book is itself very interesting and representative of how a great majority of scientists, not all mind you, approach the subject:

Claudius Ptolemy’s geocentric system has long since been dumped into the trash bin of discarded theories. Why, then, is anyone still concerned with the hoary treatise? It is because Ptolomy’s Almagest, more than any other book, convinced people that the seemingly complex phenomena of the heavens could be represented by simple underlying mathematical description, one that afforded the possibility of continuing prediction of celestial events… To understand Ptolemy’s contribution, we must appreciate the fact that he was tackling a fairly esoteric problem: how to find the positions of heavenly bodies in the sky. I say “fairly esoteric problem” because most people have rather little use for such specific information as to where Mars is to be found at a specific moment.”

Fortunate for many historians of science Ptolemy decided not to attach the Tetrabiblos, which is dedicated entirely to astrology, to the Almagest. For then this embarrassing work can be safely ignored or confined to a footnote. As we have seen this cannot so easily be done with Mesopotamian astroscience. The answer to the ‘esoteric’ problem is that astrologers were very mush interested in being able to accurately determine the positions of the planets. And although we cannot call Ptolemy a Pythagorean, a glimmer peaks through. The idea that the universe can be geometrically described so that the workings of the Architect of the Cosmos could be thus grasped does find a clear formulation in this work. Just as the Mesopotamian star-seer/see-er saw the writing of the gods in the celestial sphere so could a Hellene such as Ptolemy see the working of the divine order in the pure, regular geometry of celestial phenomena. To try to use geometrical method to describe this and to use a rational method of description to make the Appearance fit is Hellene. The theory that has been discarded cannot reflect the more modern conception of a universe defined not by geometrical order but by the principle of uncertainty.

Let us see what Ptolemy has to say for himself:

…we thought it fitting to guide our actions in such away as never to forget, even in ordinary affairs, to strive for a noble and discliplined disposition, but to devote most of our time to intellectual matters, in order to teach theories, which are so many and beautiful, and especially those to which the epithet ‘mathematical’ is particularly applied.

Two paragraphs later he says:

Hence we were drawn … especially to the theory concerning divine and heavenly things. For that reason it too can be eternal and unchanging in its own domain, which is neither unclear nor disorderly. Furthermore it can work in the domains of the other two divisions of theoretical philosophy (theology and physics) no less than they do. For this is the best science to help theology along its way, since it is the only one which can make a good guess at that activity which is unmoved and separated; it is familiar with the attributes of those beings which are on the one hand perceptible, moving and being moved, but on the other hand eternal and unchanging, having to do with motions and the arrangements of motions. (all quotes from “Ptolemy’s Almagest, translated by G.J. Toomer, Princeton University Press)

Most schoolchildern and many adults would think that the man is mad. Mathematics? What does that have to do with a noble and disciplined disposition? We see that our understanding of the word, mathematicians generally excluded (as many have an aesthetic experience of mathematics), has changed. Just as our understanding of the word ‘astronomy’ probably would have held no meaning in Ptolemy’s time. I am not sure if it even existed!

The Almagest did the later science of astronomy a service by providing, with a shift in perception to ‘physical’ philosophy, a rational basis for understanding celestial phenomena divorced from the divine. It also prevented Astrology from being proscribed as it clearly demonstrated to ‘theological’ philosophy how the transcendant Great Mover becomes immanent.

* A star by any other name would be just as bright.


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