Anyone who read my last blog post might have noticed that the Renaissance mathematici Georg Tannstetter and Philipp Apian were both noted mathematicians and practicing physicians. In our day and age if someone was both a practicing doctor of medicine and a noted mathematician they would be viewed as something quite extraordinary but here we have not just one but two. In fact in the Renaissance the combination was quite common. Jakob Milich, who studied under Tannstetter in Vienna, was called to Wittenberg by Philipp Melanchthon in 1524, as professor for mathematics, where he taught both Erasmus Reinhold and Georg Joachim Rheticus. In 1536 he became professor for anatomy in Wittenberg and was succeeded by Rheticus as professor for mathematics. Rheticus in turn would later become a practicing physician in Krakow. The man, who Rheticus called his teacher, Nicolaus Copernicus, was another mathematical physician. My local Renaissance astronomer Simon Marius was another mathematician who studied and practiced medicine. That this was not a purely Germanic phenomenon is shown by the Welsh mathematicus and physician Robert Recorde and most notably by the Italian Gerolamo Cardano, who is credited with having written the first modern maths book, his Ars magna, and who was one of the most renowned physicians in Europe in his day.

These are only a few well-known examples but in fact it was very common for Renaissance mathematician to also be practicing physicians, so what was the connecting factor between these, for us, very distinct fields of study? There are in two interrelated factors that have to be taken into consideration, the first of which is astrology. The connection between medicine and astrology has a long history.

Greek legend says that Babylonian astrology was introduced into Greece by the Babylonian priest Berossus, who settled on the island of Kos in the third century BCE. Kos was the home of the Hippocratic School of medicine and astrology soon became an element in the Hippocratic Corpus. At the same time the same association between astrology and medicine came into Greek culture from Egypt in the form of the Greek-Egyptian god Hermes Trismegistos. Both the Egyptians and Babylonians had theories of lucky/unlucky, propitious/propitious days and these were integrated into the mix in the Greek lunar calendar. The Greeks developed the theory of the zodiac man, assigning the signs of the zodiac to the various part of the body. If a given part of the body was afflicted it would then be treated with the plants and minerals associated with its zodiac sign. The central role of astrology in medicine can be found in both the Hippocratic Corpus, in Airs, Waters, Placesit is stated that “astronomy is of the greatest assistance to medicine”and in Ptolemaeus’ Tetrabibloswe read, “The nature of the planets produce the forms and causes of the symptoms, since of the most important parts of man, Saturn is lord of the right ear, the spleen, the bladder, phlegm and the bones; Jupiter of touch, the lungs, the arteries and the seed; Mars of the left ear, the kidneys, the veins and the genitals; the sun of sight, the brain, the heart, the sinews and all on the right side; Venus of smell, the liver and muscles; Mercury of speech and thought, and the tongue, the bile and the buttocks; and the Moon of taste and of drinking, the mouth, the belly, the womb and all on the left side.” The connection between astrology was firmly established in Greek antiquity and was known as iatromathematica, health mathematics.

The theory of astrological medicine disappeared in Europe along with the rest of early science in the Early Medieval Period but was revived in the eighth century in the Islamic Empire when they took over the accumulated Greek Knowledge. The basic principles were fully accepted by the Islamic scholars and propagated down the centuries. When the translators moved into Spain and Sicily in the twelfth century they translated the Greek astrology and astrological medicine into Latin from Arabic along with rest of the Greek and Arabic sciences.

During the High Middle Ages, Christian scholars carried on an energetic debate about the legitimacy, or lack of it, of astrology. This debate centred on judicial astrology, this included natal astrology, mundane astrology, horary astrology, and electional astrology but excluded so called natural astrology, which included astrometeorology and astro-medicine both of which were regarded as scientific. To quote David Lindberg, “…no reputable physician of the later Middle Ages would have imagined that medicine could be successfully practiced without it.”

Beginning in the fifteenth century during the humanist renaissance astrological medicine became the mainstream school medicine. It was believed that the cause, course and cure of an illness could be determined astrologically. In the humanist universities of Northern Italy and Poland dedicated chairs of mathematics were established, for the first time, which were actually chairs for astrology with the principle function of teaching astrology to medical students. Germany’s first dedicated chair for mathematics was founded at the University of Ingolstadt in about 1470 for the same reason.

With the advent of moving type printing another role for mathematicians was producing astronomical/astrological calendars incorporating the phases of the moon, eclipses and other astronomical and astrological information needed by physicians to determine the correct days to administer blood lettings, purges and cuppings. These calendars were printed both as single sheet wall calendars and book form pocket calendars.

These calendars were a major source of income for printer/publishers and for the mathematici who compiled them. Before he printed his legendary Bible, Johannes Guttenberg printed a wall calendar. Many civil authorities appointed an official calendar writer for their city or district; Johannes Schöner was official calendar writer for Nürnberg, Simon Marius for the court in Ansbach, Peter Apian for the city of Ingolstadt and Johannes Kepler for the city of Graz. Official calendar writers were still being employed in the eighteenth century. As I explained in an earlier post the pocket calendars led to the invention of the pocket diary.

With mainstream medicine based on astrology it was a short step for mathematicians to become physicians. Here we also meet the second factor. As a discipline, mathematics had a very low status in the Early Modern Period; in general mathematicians were regarded as craftsmen rather than academics. Those who worked in universities were at the very bottom of the academic hierarchy. At the medieval university it was only possible for graduates to advance to a doctorate in three disciplines, law, theology and medicine. It was not possible to do a doctorate in mathematics. With the dominance of iatromathematica, which depended on astrology, for which one in turn needed astronomy, for which one needed mathematics it was logical for mathematicians who wished to take a university doctorate, in order to gain a higher social status, to do so in medicine. The result of this is a fascinating period in European history from about 1400 to middle of the seventeenth century, where many of the leading mathematicians were also professional physicians. When astrology lost its status as a science this period came to an end.