The Leeds Review - Issue #1"To deny the power and influence of the stars is to detract from divine wisdom and influence"
Tycho Brahe
Astrology is the study of the influence or relation of the heavenly bodies to events on the earth. Whilst it is ridiculed now, and seen as little more than an entertainment by most, it was a vital part of life for a very long period. Ptolemy wrote on the subject in the second century AD, and its popularity in the early-modern period is not in question. In looking at the sixteenth and early-seventeenth centuries one must consider astrology as a part of astronomy. This is the starting point for an examination of the relationship between the two.
Astronomy, at the start of the sixteenth century, was taught in universities as part of the 'quadrivium' , which also included arithmetic, geometry and music. Astrology was taught as a part of astronomy, and this simple relationship goes a long way in understanding how 'important' astrology was for astronomy. Among the basic texts for teaching astronomy were Sacrobosco's De Sphaera, cosmographical texts, and astrology was taught using Ptolemy's Tetrabiblios and the pseudo-Ptolemaic Centiloquium. The increasing popularity and use of the cosmographical works, which covered the calendar, instruments and practical calculations, stresses the importance of making useful the theory of mathematical astronomy.
Astrology was one of these uses for astronomy, and this relation between the practical and the theoretical will be a recurring theme throughout this essay. Astrology was in everyday use, for it focused around medicine and weather prediction, but extended into all areas of life, and was considered relevant to most people. Every ailment had treatments affected by the positions of the planets or phases of the moon, and each part of the body was governed by a corresponding zodiac sign. In circa 1510 Cornelius Agrippa wrote: "Things pertaining to Mars are ascribed to the head and testicles because of Aries and Scorpio". (1) Further, what your talents were, supposedly, depended on the planets, and when something of note was to be undertaken an astrological table was referred to. This had important ramifications for astronomers: astrology could provide an income. The demand for accurate tables was such that the accuracy of astronomical measurement and prediction was constantly forced to improve. Astrology can be seen, therefore, as a driving force for astronomy.
As mentioned, Ptolemy's Tetrabiblios was actually on the syllabus for teaching astronomy. This is an important point, for the early sixteenth century was a time of great respect for the classical authors. Indeed the humanist movement, characterised by publishing under Latinised names and claiming to 'follow on' from classical authors, was in full flow at the turn of the century. Regiomontanus was the model humanist astronomer (and was held in high regard as an astrologer), and many more were to follow in his footsteps. Indeed it is by his Latinised name that we now know Niclaus Kopernig (Copernicus), and his De revolutionibus claimed to be a continuation of classical sources. This classicisation also influenced the particulars of astrology. The most popular view was that of the microcosm/macrocosm, and was taken, primarily, from Proclus, among others. This view held that the body was a microcosm reflecting the earth, and in turn, the heavens. Each is inside the other, and the link is causal and real. While not all held this view, most did, and it is what led to the beliefs concerning medicine.
So far, then, we have seen that astrology was a part of astronomy, and in many ways drove it onwards. The humanist movement paid great respect to authors such as Ptolemy and Proclus, and if the latter believed in the powers of astronomy it is not surprising that the former followed suit. It must be said that the 130 years following 1500 were characterised by change, not stability, and although astrology flourished throughout the period, it certainly featured in the changing attitudes of the time. It is this shifting nature of astrology that I will now concentrate on.
The most obvious way in which the relationship remained the same was that astrology always required more accurate prediction . This was facilitated by the trend in astronomy for reliance on observation, accurate measurement and new types of instrument. Astronomy was also affected by other factors. The New World was recently discovered, and the success of nations depended on accurate navigation. This required more accurate astronomical instruments, and these were duly made . Further, the humanist movement that so embraced the classical authors at the start of the sixteenth century was beginning to give way to questioning of these sources, and a general belief that discoveries not made before could occur . This was centered around a rebellion against neo-Aristotelian scholasticism, but stretched into all areas of education, although the change was, of course, slow. Still, this didn't have much affect on the daily business of predicting the weather, practicing medicine and casting horoscopes. To see what did affect astrology we will have to look back to the very first source: Ptolemy's Tetrabiblios.
The main aims of the Tetrabiblios were to provide a kind of framework for 'doing' astrology, and to seek out foundations on which to base the subject ; foundations stronger than superstition. In his first aim, Ptolemy was undoubtedly successful, the general nature of the text ensured its popularity, for it let others do the actual work of creating tables, and merely provided the general theory. The second aim, to set astrology on a surer footing, can be said, by today's standards at least, to have been a failure. Obviously this wasn't so damaging that astrology was not trusted in the sixteenth century, rather, it was left to others to seek the solid foundations . This task was taken up by many, among them was Johannes Kepler, who did so around the turn of the seventeenth century.
Kepler was certainly a believer in astrological principles although, like Regiomontanus, he thought astrology to be influential rather than causal . It is no coincidence that his heliocentric planetary model reflected the sun-centered nature of astrology. The sun was the most important symbol for astrology; it governed most of the body . But Kepler wanted to set firm mathematical principles for astrology to be based on, and in 1601 he published On the more Certain Principles of Astrology. Kepler serves as another illustration of the importance of astrology to astronomers, for it provided him with notable patronage. He tutored Rudolph II on astrology, and in 1627 he completed Tycho Brahe's unfinished Rudolphine Tables. By this time, however, there were other factors that would affect astrology in the long term, and this aim of setting foundations for astrology can be seen to become more and more precarious.
The early seventeenth century was a time in which the modern view of what science should essentially consist of was formed. Whether there was a 'revolution' or not, and when it actually occurred is beside the point. It is easier to look at the period as a continuation of what went before, and a time full of precedent for what was to follow. I have already mentioned the rejection of scholasticism, and the increased quality of, and reliance upon, instrumentation. These factors, together with the recurring theme of trying to set mathematical, unchanging, and most importantly, verifiable foundations for astrology, all led to its eventual downfall. This did not occur during the time period under examination, but rather, the groundwork was set for what would turn astrology into the non-subject that it is today. This change does not have one cause, for there were many factors that affect any change in attitude over a long period of time. However, it cannot be said that the writings of Francis Bacon and Descartes, among others, did not influence the acceptance of the new, largely experimental, natural philosophy.
There are two main points to be taken from examining the relationship between astrology and astronomy between 1500 and 1630. First: astrology was a part of astronomy. It was a practical use for the theoretical and observational study of the heavens. Second: 1500 to 1630 was a time period which began with the humanist idolisation of classical authors, and ended with the rejection of scholasticism, and an entirely new experimental philosophy. The irony is that at least some part in this change of attitude was taken by the importance of 'practical' subjects such as surveying, navigation and astrology; so one of the driving forces for astronomy was eventually undermined by the new philosophy it helped to create.
Georgia Morris Info