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Studies in History and Philosophy of Biological and Biomedical Sciences 41 (2010) 125134

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Studies in History and Philosophy of Biological and

Biomedical Sciences
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Instruments and demonstrations in the astrological curriculum: evidence from

the University of Vienna, 15001530
Darin Hayton
Haverford College, 370 Lancaster Avenue, Haverford, PA 19041, USA

a r t i c l e
University of Vienna
Georg Tannstetter
Andreas Stiborius

i n f o

a b s t r a c t
Historians have used university statutes and acts to reconstruct the ofcial astrology curriculum for students in both the arts and medical faculties, including the books studied, their order, and their relation to
other texts. Statutes and acts, however, cannot offer insight into what actually happened during lectures
and in the classroom: in other words, how and why astrology was taught and learned in the medieval university. This paper assumes that the astrology curriculum is better understood as the set of practices that
constituted it and gave it meaning for both masters and students. It begins to reconstruct what occurred
in the classroom by drawing on published and unpublished lecture notes. These offer insight into how
masters presented the material as they did, and why. The paper argues three points: rst, the teaching
of astrology centered on demonstrations involving astrological instruments: specically, various kinds
of paper astrolabes. Second, the astrological instruction focused on conveying the pragmatics of astrology
rather than esoteric, theoretical issues. Finally, astrology as it was taught in the arts curriculum was
explicitly intended to provide a foundation for students who would advance to study medicine at the
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When citing this paper, please use the full journal title Studies in History and Philosophy of Biological and Biomedical Sciences

1. Introduction
On the rst Thursday in March, 1519, students gathered to hear
Andreas Perlach, a young master in mathematics and astrology at
the University of Vienna, deliver his opening lecture on almanacs.
Perlach began with the basics:
The Arabic Almanac, Latin Diale or Diurnale, Greek Ephemerides, is a book in which the planets are presented from
day to day. Note: each planet and each zodiacal sign has a certain resemblance or likeness to its symbol, which denotes that
actual planet, and therefore those symbols are not assigned by
chance or accident. Accordingly the symbol of Aries is as follows
, which resembles two horns like those of a ram.1

In this rst lecture Perlach worked through the symbols for the
zodiacal signs and the planets. Although the notes end abruptly
after Perlachs introductory remarks, they provide a tantalizing
glimpse at the astrological curriculum at the University of Vienna,
a curriculum that thrived below the surface of ofcialdom. Perlachs lecture on almanacs occurred on a Thursday afternoon, a
time typically reserved for extraordinary lectures. Falling outside
the strictly prescribed curriculum, extraordinary lectures offered
masters a chance to lecture on and students the opportunity to
hear subjects that were not fully treated in ordinary lectures. At
the University of Vienna, the students had to pay particularly high
fees to hear extraordinary lectures. Masters there supplemented
their income through these fees, provided they offered lectures

E-mail address:

A magistro Andrea perlachio Stiro Super Almanach collectanea 1519 die jovis ante Esto mihi. Almanach arabum, Diale/Diurnale latinum, Ephemerides grecum est liber in quo
astra de die in diem destribunture. Nota Quilibet planeta eciam quodlibet zodiaci signum quandam habent commemenciam [sic] seu similitudinem ad suum characterem qui
ipsum denotat non ergo fortuitu et a casu illi characteres impositi sunt. Est igitur arietis character talis qui videtur duo cornua qualia arietis sunt representare (Andreas Perlach,
Super almanach collectanea, NB Hss. Cvp S.n. 4265, fol. 307v).

1369-8486/$ - see front matter 2010 Published by Elsevier Ltd.



D. Hayton / Studies in History and Philosophy of Biological and Biomedical Sciences 41 (2010) 125134

that would attract students willing to pay those fees.2 Simply because these lectures were not prescribed, however, did not necessarily make them ephemeral or insignicant. Perlachs lectures in 1519
apparently found a receptive audience and became part of his teaching at the university for the next thirty years. During this time he expanded and rened his lectures on almanacs. In 1551 he published a
thick textbook based on his lectures, his Commentaria
The University of Vienna presents something of a puzzle for historians of astronomy and astrology. During the fteenth century
the university was alma mater to Johannes de Gmunden, Georg
von Peuerbach, and Johannes Regiomontanus, who were central
to developments in astronomy and astrology throughout Europe.
Yet there is little evidence of advanced instruction in astronomy
or astrology by any of these masters. Historians have expected to
nd their innovations reected in the curriculum.4 However, the
ourishing astronomical and astrological activity in Vienna seems
to have had little impact on the university. Unlike the universities
of Pavia, Bologna and Krakow, the University of Vienna had no chair
in astrology.5 Ofcial documents provide no trace of Gmundens,
Peuerbachs, or Regiomontanuss developments in astronomical
and astrological theory and practice. Indeed, the statutes, which prescribed the ofcial courses of study students were expected to attend, suggest that the curriculum had ossied early in the fteenth
century and did not change until the reforms under Archduke Ferdinand in the 1520s.6 The Acts of the Arts Faculty as well as the Acts of
the Medical Faculty are similarly silent regarding any curricular
innovations or changes.7 Although Peuerbach composed what became the most important textbook on astronomy, he lectured on
the Latin poets Juvenal, Horace and Virgil.8 Historians have suggested that the interesting curricular developments occurred below
the threshold of ofcialdom.9 We can begin to recover the contours
of the astrological curriculum by looking closely at students lecture
notes that survive from the early sixteenth century.
During the early decades of the sixteenth century a close-knit
group of masters at the University of Vienna were responsible for
much of the education in astrology and astronomy there. This
group included masters recruited from neighboring universities,
such as Johannes Stabius and Andreas Stiborius who came from
the University of Ingolstadt, as well as students who had been educated elsewhere but came to Vienna to become university masters,
such as Georg Tannstetter. By the second decade of the sixteenth
century recent members of this group had been educated at the
University of Vienna and had stayed there to teach in the Arts or
the Medical Faculties, including Andreas Perlach and Johannes
Vogelin. Examining the careers of Andreas Stiborius and Georg
Tannstetter through students lecture notes allow us to begin to
reconstruct the astrological and astronomical instruction at the
university. These notes reveal a vibrant astrological curriculum

that has largely escaped notice. Stiborius and Tannstetters lectures reveal the importance of astronomical and astrological
instruments in the astrological curriculum, and how these instruments were used as demonstration devices to convey practical
knowledge. Finally, their lectures uncover the close interactions
between the Arts Faculty and the Medical Faculty, at least in regard
to the use of instruments in the practice of astrology.
2. Andreas Stiborius and astrological instruments
Andreas Stiborius began his career at the University of Ingolstadt, where he lectured on astronomical topics, including the use
of instruments such as the astrolabe.10 In 1497 he left his teaching
position there and moved to Vienna. Not long after he arrived at the
University of Vienna, Stiborius began holding lectures entitled Liber
umbrarum.11 The Liber umbrarum were Stiborius foundational
lectures on various methods of stereographic projection and the uses
of astronomical instruments, usually different types of astrolabes.
Although he had probably held similar lectures in Ingolstadt, he revised them when he came to Vienna, drawing on information specic to Vienna for his examples. His descriptions and calculations
regularly use the south face of the universitys tower as a point of
reference for the polar elevation, the zenith, the latitude, or other
celestial descriptions.12 These lectures introduced various methods
of determining the important astronomical information for any given location and then explained how to use this information to
establish the time of day, the rising and setting of constellations,
and the degree of the rising sign. The Liber umbrarum also formed
the basis for Stiborius more sophisticated lectures on astrological
instruments and played an important role in his larger series of lectures at the University of Vienna. Although he treated summarily the
stereographic projection used to make a standard planispheric astrolabe, Stiborius spent most of his time and effort discussing the methods of stereographic projection that underlay various universal
The standard planispheric astrolabe was based on a projection
of the heavenly sphere onto a surface coplanar with the equator.
Because the visible portion of the sky varies with latitude, such a
projection is accurate for only a narrow latitude. Consequently, a
standard astrolabe usually had a number of plates for different latitudes, often for specic cities such as Rome, Paris, Vienna, or London. A universal astrolabe, by contrast, relied on a projection of the
heavenly sphere onto a plane perpendicular to the plane of the
equator. The resulting projection is valid for all latitudes, removing
the need for multiple plates for different latitudes. Of the various
universal projections, Stiborius was particularly interested in the
saphea, which assumed a point of projection innitely distant on
the line formed by the equinoctial points, that is, the line formed
by the two points where the ecliptic crossed the celestial equator.

On the importance of the extraordinary lectures and private lectures, especially regarding the income masters could realize from these lectures, see the early statute from
Vienna that outlines the fees for some of the extraordinary lectures (Kink, 1854, p. 215). A later statute from 1509 points to other supplementary lectures and the fees associated
with them (ibid., p. 317). On the relative difference in fees between Vienna and Paris, see Rashdall (1936), p. 243 n. 1.
Perlach (1551). This textbook represents the culmination of Perlachs long career at the University of Vienna and his lectures on almanacs. He rst published a handbook on
almanacs in 1518 (Perlach, 1518).
On the developments in astrology and astronomy during the fteenth century, see Klug (1943); Zinner (1968); Grssing (1983). This literature needs to be consulted with
For a recent study of astrological studies at the University of Pavia, see Azzolini (2005).
On Ferdinands reforms, see Mhlberger (2003, 2005).
On the statutes and the course lists in the acts, see Kren (1983, 1987).
Shank (1996).
Shank (1997), p. 269.
There is little evidence of Stiborius actual lectures at Ingolstadt (see Schner, 1994, p. 212).
I have been able to locate only a fragment of these lectures, copied in 1500 by Jakob Ziegler. Zeigler noted at the end of his copy that the original he had used was missing the
last section (Andreas Stiborius, Liber umbrarum, BSB Clm 24103, fol. 21v). There is no evidence that Ziegler ever studied at Vienna, though he was certainly familiar with the both
Stiborius and Tannstetters lectures there. In addition to this text, he printed Tannstetters commentary on Plinys Historia naturalis.
All of Stiborius examples use data for Vienna. Some of these are quite specic: Describatur itaque primo Meridianus secundum gradus declinationis cancri scilicet 27
computatis a meridie ad occasum qualiter est supercies meridiana turris collegij Vienne (Stiborius, Liber umbrarum, BSB Clm 24103, fol. 5r).


By using a saphea, a person could, in principle, make an instrument

with a single plate that was valid for all latitudes. The instrument,
however, introduced a number of challenges, and despite its apparent advantage, the saphea and related universal astrolabes remained far less common. Just as the theory of stereographic
projection that undergirded the saphea was unfamiliar, how to
use the saphea to carry out actual calculations was also unfamiliar.13 For these reasons, Stiborius focused almost exclusively on
the different techniques for using universal astrolabes. He explained
to the student how to determine the elevation of the pole, how to locate the horizon and the zodiacal houses, how to tell time and to nd
the positions and the rising and setting times of constellations.14
Throughout his lectures Stiborius described the various operations
as if the students had ready access to an astrolabe, instructing them
to place the rule on a particular point and then nd where the rule
crosses the limb of the instrument, explaining how to inscribe different hour lines on the surface of an astrolabe.15 It would have been
impractical for Stiborius to use a typical, brass astrolabe as a demonstration device in his lectures. Astrolabes were generally too small to
be seen from a distance of more than a few feet. Moreover, marking a
brass instrument with the reference points he refers to in his lectures would have been difcult. And it would have been prohibitively expensive for each student to have his own brass
astrolabe.16 Instead of relying on brass instruments, Stiborius probably used cheaper, paper instruments in his lectures. It is possible
that during his lectures Stiborius gestured to a large, paper astrolabe.17 Such an instrument could have been colored, as Stiborius
claims in a later lecture, and would have functioned well to demonstrate how to move the various parts of an astrolabe.18 At the same
time, Stiborius students could have easily afforded their own paper
astrolabes, which they could have colored according to Stiborius
instructions during his lectures. In this way, Stiborius could indicate
clearly what portions of the instrument were to be manipulated
while students performed the operations on their own paper
Throughout his career, Stiborius reexamined the advantages
and disadvantages of different methods of stereographic projection. His subsequent lectures often contain long discussions on various projections and the usefulness of certain ones over others.
Already in his Liber umbrarum Stiborius was looking forward to
future lectures: All these projections can be variously arranged.
Because there are innumerable theories of projection, I intend to


write a little book specically on each of these. Their amazing uses,

which up to this point have been described by no one, will be laid
out.19 The Liber umbrarum provided the foundation for much of
Stiborius later work both in content and in style. Not only did he
establish his area of expertise but he also initiated a series of teaching practices that would become standard in his lectures. Stiborius
lectures focused on astronomical instruments and consistently relied
on such instruments as demonstration devices in those lectures.
Despite the importance of the Liber umbrarum for Stiborius
larger project, and whatever popularity these lectures might have
enjoyed, Stiborius lectures did not appear on the ofcial lecture
lists compiled at the beginning of each year. Moreover Stiborius
himself did not seem to occupy an important position at the university.20 His lectures on astrolabes, however, continued a long tradition of lectures on astronomical instruments stretching at least as
far back as the 1430s when Gmunden lectured on the astrolabe.21
Stiborius Liber umbrarum also must have enjoyed some popularity.
Masters at the University of Vienna relied heavily on income provided by students who attended private or extraordinary lectures.
Since Stiborius Liber umbarum did not appear on the lecture lists,
it seems likely that he lectured on astronomical instruments in private or extraordinary lectures.22 Everything changed in 1501 with
the founding of Conrad Celtiss Collegium poetarum et mathematicoruma graduate faculty at the university. Stiborius was appointed
to one of the two chairs in mathematics and astronomy at the Collegium. Two years later he was appointed to a chair in the Collegium
ducale. By 1503 Stiborius had become one of the rising stars of the
University of Vienna, with appointments in two colleges and his
pay coming directly from the imperial coffers.23 Stiborius wasted
no time and quickly developed a series of lectures that expanded
his treatment of astrolabes that he had begun in his Liber umbrarum. He would continue these lectures throughout his career at
the university.
Perhaps as early as 1504 Stiborius had completed at least one
new set of lectures, his Canones astrolabij.24 In these Stiborius
turned his attention back to the standard astrolabe and its uses.
He began simply enough, laying out the basic techniques needed
to carry out more complicated calculations. He treated fundamental
astrological topics such as locating the sun and the planets as well as
determining the four cardinal pointsthe ascendant, medium coeli,
descendent, and imum coeliand the remaining horoscopic house
divisions. He also covered various time-telling conventions in use

Emmanuel Poulle has tried to explain the discrepancy between the number of texts on universal astrolabes and the near absence of actual universal astrolabes by suggesting
that the texts formed an important part of the astronomy education. Stiborius discussion of the saphea supports this claim (see Poulle, 1969). The lack of popularity of these
instruments can be inferred from the surviving instruments in museum collections, which often contain only a handful of universal astrolabes while they list dozens of standard
astrolabes. For example, see the online catalog of astrolabes from the Museum of the History of Science (2006). See also the printed catalog from the Adler Planetarium, Webster &
Webster (1998); Turner (1985). The Epact online catalog, which combines the instruments from the Museum of the History of Science, Oxford, the Instituto e Museo di Storia della
Scienza, Florence, The British Museum, London, and the Museum Boerhaave, Leiden, likewise lists only a few universal astrolabes. Although the universal astrolabe was developed
in the Islamic context, the saphea and related instruments failed to enjoy much popularity amongst Islamic makers (see Gibbs & Saliba, 1984).
Stiborius, Liber umbrarum, BSB Clm 24103, fols. 1v7r.
For example, ibid., fols. 5v, 7r, 13r.
If a signicant number of students had owned astrolabes, some of those instruments would have to survive. Unfortunately, no metal astrolabe survives that can with any
certainty be traced back to this early sixteenth-century Viennese milieu. One possible candidate is an astrolabe dated 1521 that resembles Georg Hartmann astrolabes. Accounting
for this lack of material evidence presents another challenge for historians. The tentative suggestions offer a tentative solution to this difculty.
For an extended study of paper instruments and related printed devices, see Schmidt (2006), especially pp. 180274.
In a later set of lectures Stiborius told his students how to color an astrolabe to correspond to the motion of the four humors (Stiborius, Canones astrolabij, BSB Clm 19689,
fols. 75r75v).
Haec omnia licet sibi invicem varie commisceri. Ideo proieccionum speculationes sunt inexhaustae de quo seorsum specialiter intendo scribere libellum in quo mirici usus a
nemine hactenus descripti docebuntur (Stiborius, Liber umbrarum, BSB Clm 24103, fol. 13).
The lectures for the upcoming year were distributed at the rst faculty meeting each year, in mid-September. These lists are recorded in the Acts of the Arts Faculty. There is
no indication that Stiborius was assigned any books. For the lecture lists during Stiborius tenure at the university, see Acta facultatis artium Universitatis Vindobonensis, Vol. IV:
14971555, UAW Cod. Ph 9. For an analysis of these lists that extends to the late fteenth century, see Kren (1983, 1987).
Kren (1987), p. 19.
On the importance of private and extraordinary lectures, see Kren (1983), pp. 2122.
Grssing suggests that Stiborius along with Georg Tannstetter and Johannes Stabius were the most important members of the second Viennese mathematical school (see
Grssing, 1983, p. 174).
Two copies of this text survive, one of which includes the comment: et advertens poeta laureatus et Imperatoris Romanorum Maximiliani historiographus atque
Cosmographus Joannes Stabius, vir numeri seculi doctissimus. Stabius was crowned poet laureate sometime in 1503/1504. Stiborius, Canones astrolabij Magistri Andree Stiborij
boij partim ex veteribus ordinate partim nov invencione additi, BSB Clm 19689, fol. 77v.



and how to convert between them. He recognized that his students

were, for the most part, interested in the real-world applications,
rather than the theoretical issues that lay behind those applications.
Accordingly, he introduced theoretical points only when needed to
carry out the desired operation. Stiborius pragmatic approach is further reected in the fact that once again he clearly expected all of his
students to have access to an astrolabe, or at least a model of one. His
instructions for nding the right ascensions of the signs are typical of
his approach. He begins by stating the canon, dening the terms, and
then explaining how to solve the problem. Stiborius explicitly relies
on an astrolabe, instructing the student on how to move various
parts and how to read the results from the face of the instrument.25
Throughout Stiborius concentrated on how to use an astrolabe
to solve a wide range of practical, astrological problems, such as
determining the true ascendant at the time of an election or conjunction, dividing the zodiac into houses, and predicting the motions of the humors. At least one of his students was excited by
Stiborius lectures and recognized their immediate applicability
to astrology, noting in the margin of his text that these applications
were not found in previous treatises and will be useful for judgments.26 Stiborius originality here was not as great as he suggested,
though he did strive to bring together operations that were spread
throughout a rather broad literature. More importantly, Stiborius
was foregrounding instruments in both his own teaching and in
the practical tasks of astrologers and physicians.27 He explicitly
linked his lectures to other courses at the university, drawing attention to topics that his students would encounter again during their
time at the University of Vienna. When he pointed out that a physician could use an astrolabe to predict the ux and reux of humors
or to determine the critical days of a disease, he was saying little that
was newastrology had long been used to predict the course of diseases and humors.28 He did, however, draw attention to the astrolabe as a means of facilitating prognosis, and he provided his
students with a preview of topics they would encounter in a few
years in Georg Tannstetters lectures on medical astrology. Indeed,
Tannstetters students would have been well advised to return to
their notes from Stiborius class, where they would nd detailed
instructions for employing an astrolabe in medical practice.29
Stiborius lectures on standard astrolabes provided his students
with the foundation necessary to advance to more sophisticated
and complex astrolabes, namely universal astrolabes. Stiborius
presented the rst of these in his lectures Canones saphee.
Although the saphea had been known for nearly three centuries,
it had never enjoyed the popularity of the standard astrolabe,
which provided simple solutions to the most common tasks astrologers needed to accomplish. Stiborius recognized that his students
would most likely be unfamiliar with the saphea and so opened


with a brief denition, history, and justication of the instrument.30 He emphasized the advantages offered by the saphea, pointing out that it solved terrestrial problems as well as celestial
problems, and that the range of problems could be extended when
the saphea was tted with a special rule and a type of rete, that is,
a map of the stars that rotates about the center of the instrument
to indicate the positions of the stars in the sky.31
When he turned to the substance of his lectures, Stiborius remained sensitive to the fact that his students might be unfamiliar
with the saphea and went to great pains to present the various
operations in a logical progression of increasing complexity. He began with those tasks that could be solved simply by using the face
of the instrument. These canons occupy only a small section of the
lectures and focus how to tell time, to determine the rising and setting time of the sun, or to calculate the distances between towns.32
When tted with a rete and moveable zodiac, however, the saphea
became a handy astrological tool, useful for quickly calculating the
rising time of signs, the mundane houses, and the ascendant, as well
as determining the medium coeli, and the positions of the constellations.33 Stiborius concluded his lectures with a list of alternative
methods for nding the cardinal points of a horoscope, dividing
the zodiacal houses, and adjusting the signicator in order to determine critical days and to cast elections.34
These canons depended not only on the earlier ones presented in
these lectures, but also on Stiborius previous lectures on the
Canones astrolabij, and Liber umbrarum. At times he simply
referred his student to his former lectures for a detailed treatment
of some point or other.35 The close relationship between Stiborius
lectures was not lost on his students, some of whom bound their
lecture notes together in the appropriate order for easy reference.36
The series of lectures Stiborius developed at the University of Vienna
focused on the astrological uses of various types of astrolabes.
Throughout his lectures he refers to astrolabes to illustrate particular
operations, and he instructs students to manipulate their own astrolabes. Although instruments were at the center of Stiborius lectures,
he clearly understood them as astrological tools. Whether or not he
was the only master at the university at that time lecturing on astrological instruments, Stiborius was continuing a long tradition in
Vienna that situated astrolabes and related instruments at the center
of astronomical and astrological teaching. In the 1430s, Johannes de
Gmunden lectured on astrolabes while Johannes Angerer de Mlldorf
lectured on the Richard of Wallingfords albion. A decade later Martin
Hemerl was again lecturing on astrolabes.37 Regiomontanus extended
their work in his lectures on various astrological instruments.
Although Stiborius status at the University of Vienna continued
to improve during his tenure there, he failed to appear in any of the
ofcial course lists or lectures.38 His ofcial absence neither

Ibid., fol. 73v.

One student placed the following heading at the beginning of the second part: Secuntur utilitates addite A. Magistro Andrea Stiborio que in antequis exemplarijs non
habentur et iudiciarie deservient (ibid., fol. 74v).
One of the main points in Jim Bennetts recent article is that astrolabes and indeed most instruments in the sixteenth century were instruments of doing rather than
knowing. By that he tries to emphasize the fact that instruments were practical devices aimed at providing a solution to a problem or response to a particular question (see
Bennett, 2003, esp. pp. 135136). For a discussion of the changes in expectations about instruments, see also Warner (1990).
On the relations between astrology and medicine, see in general Siraisi (1990), esp. Ch. 5; OBoyle (1991, 2005); French (1994); Azzolini (2005).
For example, Stiborius, Canones astrolabij, BSB Clm 19689, fols. 75r76r.
All three surviving copies of this text begin with exactly the same passage. See, for example, Stiborius, Canones saphee, BSB Clm 24103, fol. 22r.
Stiborius, Canones saphee, BSB Clm 19689, fol. 293v.
Ibid., fols. 297v306r.
Ibid., fols. 306r308r.
Ibid., fols. 308r312r.
For example, . . . de quibus latius in canonibus astrolabij et libris meis umbrarum mencionem feci (Stiborius, Canones saphee, BSB Clm 19689, fols. 311v, 312r).
The surviving copies of Stiborius lectures are bound in the order in which the students would have attended them: BSB Clm 19689: Canones astrolabij, fols. 67r84r,
Canones saphee, fols. 292v316r, Canones super instrumentum universale, fols. 317r322v; BSB Clm 24103: Liber umbrarum, fols. 1r21r, Canones saphee, fols. 22r34r,
Canones super insturmentum universale, fols. 35r38r; BSB Clm 24105: Canones saphee, fols. 69r84r, Canones super instrumentum universale, fols. 85r88r.
Kren (1983), pp. 1920.
Although the Acts fail to record the lecture lists for various years after 1500, Stiborius fails to appear in any of the ofcial lists. It seems reasonable to infer that his lectures
never formed part of the prescribed curriculum.


deterred students from attending his lectures, which were probably

given as extraordinary lectures, nor affected his reputation.39 Jakob
Ziegler, renowned for developing an historical geography, was interested enough in Stiborius lectures to copy out the version he was
able to acquire, even though he feared that it was incomplete.40
The famous Swiss humanist Joachim Vadianus, likewise, guarded
his copy of Stiborius Canones astrolabij, taking it with him from
Vienna when he returned home to St. Gallen.41 And more than forty
years after Stiborius death, Joachim Rheticus praised his accomplishments in developing various instruments and astronomical
Although Stiborius concentrated on different types of astrolabes, he recognized that instruments formed only one part of
the larger practice and teaching of astrology.43 He admitted that
in order to understand his lectures, students would also have to
know and understand the theories and causes of celestial motions
and phenomena. Indeed, he characterized his own work on instruments as built upon this foundational body of knowledge, exemplied in the work of his younger colleague and one-time student
Georg Tannstetter. In his second prefatory letter, this one to Tannstetters edition of Regiomontanuss Tabulae primi mobilis, Stiborius
explicitly states that all his work on instruments is dependent on
Regiomontanuss tables and calculations:
Likewise, innumerable instruments depend on this knowledge
of the primum mobile: the astrolabe, saphea, organum ptolomei, meteorscope, armilary sphere, torquetum, rectangle, equatoria, compass, quandrant and many other similar types. Oh
how splendid, how noble, how necessary for all students of
astronomy, just as the alphabet is preliminary knowledge, without this nothing is nished, nothing accomplished in this preeminent discipline of astronomy. Therefore, you who are a
true friend of the heavens, take these tables produced and
printed with diligence and solicitously by my dear colleague
Georg Tannstetter.44
Stiborius closing statement was more than just hollow praise. By
this time, he and Tannstetter had long been colleagues and close
friends. Their relationship had begun when Tannstetter studied un-


der Stiborius at the University of Ingolstadt.45 Their friendship continued when they both moved to Vienna, where they worked
together throughout their careers at the University of Vienna.46
Tannstetters interest in the theoretical and calculational facets of
astrology offered the perfect complement to Stiborius concentration
on instruments and observations.

3. Georg Tannstetter, editor and lecturer

Georg Tannstetter arrived at the University of Vienna in 1501.
His move to Vienna was, like Stiborius, precipitated Emperor Maximilian Is efforts to revive the university. Stiborious seems to have
helped Tannstetter obtain his initial appointment in the Arts Faculty.47 Tannstetter quickly established a reputation as a talented
mathematician, especially as applied to the problems of astronomy
and astrology. By 1505 he had taken over the task of producing
yearly judicia and wall calendars.48 Tannstetters lectures, however,
rarely appeared in the ofcial lists of ordinary lectures compiled at
the beginning of the academic year.49 Twice he agreed to lecture
on the Theorica planetarum, once as a young new faculty member
in 1505 and again in 1511, as an established master at university.50
Although the Acts of the Arts Faculty do not indicate which version
of the Theorica Tannstetter had selected, a few facts suggest that he
probably intended to lecture on Peuerbachs Theorica planetarum
First, Tannstetter closely annotated his copy of Albertus de Brudzewos Commentum in theoricas planetarum Georgii Purbachii,
which was published in 1495 and quickly became the standard
commentary on Peuerbachs treatise.51 Furthermore, by the mid1510s Tannstetter assumed that his students would be familiar with
Peuerbachs Theorica, casually citing or quoting the text a number of
times in his own lectures.52 Finally, perhaps sensing a lack of readily
available editions of Peuerbachs Theorica, Tannstetter produced in
1518 a small, affordable edition of this text paired with Sacroboscos
De sphaera.53 This book was clearly intended for use in the classroom, combining Sacroboscos more elementary text with Peuerbachs more advanced text. Any student wishing to progress in the

Claudia Kren suggests that the ofcial lectures at the University of Vienna reect only a small portion of the activities of masters there. Michael Shank reiterates this claim in
his discussion of astrological consulting at the university in the late fteenth century (see Kren, 1983; Shank, 1997).
Zieglers copy of the Liber umbrarum is today in BSB Clm 24103, fols. 1r21r.
Vadianuss copy of the Canones astrolabij is found in KBV Vadianische Sammlung, MS 66, fols. 43r83r.
See Rheticuss dedicatory letter to Emperor Ferdinand I in his edition of Johannes Werner, De triangulis sphoericis libri quatuor. De meteoroscopiis libri sex (Rheticus, 1557).
There is some evidence that Stiborius interests ranged rather broadly. The most signicant of this is found in Georg Tannstetters Viri mathematici that he added to his 1514
edition of Peuerbachs Tabulae eclipsium. Tannstetter groups Stiborius works into six categories: perspective, geometry, astronomy, arithmetic, metaphysics, and magic. On
Tannstetters Viri mathematici, including the text and a German translation, see Graf-Stuhlhofer (1996), pp. 154171.
Pendent item ex hac primi mobilis scientia instrumenta pene innita. Astrolabium: saphea: organum Prolaemei: metheoroscopion: armilae: torquetum: rectanguls:
aequatoria: compassi: quadrantes: & alia id genus multa. O quam ampla: quam nobilis: quam necessaria omnibus astronomiae studiosis: & tanquam alphabetaria & prliminaris
scientia. sine qua nihil perfectum: nihil consummatum in hac astronomica prcellenti discplina. Age igitur quisquis es cli verus amator has tabulas ductas diligentia &
sollicitatione confratris mei charissimi doctoris Georgii Tannstetter impressioni datas (Stiborius, 1514, sig. AA3v).
On the relationship between Tannstetter and Stiborius at the University of Ingolstadt, see Schner (1994), pp. 255261.
For example, they co-authored a work on calendar reform, undertaken at the emperors request and published in 1514 (Stiborius & Tannstetter, 1514).
Tannstetter had intially been allowed to examine students before being appointed a master in the arts faculty. See Acta facultatis artium, UAW Cod. Ph 9, fols. 4, 30v, 32v.
The emperor charged the university with the task of producing the annual wall calendars, probably with the expectation that Tannstetter would be responsible for completing
the task. Tannstetter composed wall calendars and complementary judicia and practica for over two decades, until the late 1520s.
Graf-Stuhlhofer has tried to explain the lack of evidence for Tannstetters teaching by arguing that he was, in fact, part of Celtiss Collegium poetarum et mathematicorum, and
that after Celtiss death in 1508 Tannstetter continued to lead this college until the late 1510s. See Graf-Stuhlhofer (1996, 1999, 1981, esp. p. 28).
Acta facultatis artium, UAW Cod. Ph 9, fols. 4, 41v, 75v. It is possible that he lectured on this text earlier, but there is no record of it. The Acts of the Arts Faculty fail to report
booklists for a number of years in the early sixteenth century, for example, between 1502 and 1505 the Acts contain no booklists.
This book, along with fteen other texts from Tannstetters library, was acquired by the rare book dealer, H. P. Kraus in 1966. All these texts were bound together in a
sixteenth-century binding until H. P. Kraus separated them and sold the individual tracts. Tannstetters copy of Brudzewo was purchased by Columbia University, where it
remains today. For a description of the original Sammelband, see Kraus (1971), pp. 112115. See also H. P. Krauss sale catalog, Kraus (1973), nos. 1, 2, 4, 5,10, 12, 14, 17, 65, 71, 73.
In his lectures on ephemerides, Tannstetter cites Peuerbach no less than six times, often quoting the Theoricae. See, for example, Georg Tannstetter, Georgij Collimitij Dictata
in Ephemerides, KBV Vadianische Sammlung, MS 66, fol. 28v.
I follow Graf-Stuhlhofer here, and before him both Gnther and Aschbach, in ascribing this text to Tannstetter. Although his name does not appear on this text anywhere, he is
most likely the editor. Like a number of his other works, it was paid for by Lucas Alantse, Bishop of Vienna and long-time supporter of the various mathematical disciplines at the
university. Tannstetters coat of arms appears on the colophon along with the same woodcut that adorns his 1514 edition of Peuerbachs Tabulae eclypsium. There is little work on
Alantse and his brother, Leonard, who funded so many of the texts produced by the masters at the University of Vienna. A full study of these two men would be an enormous
contribution to our understanding of the development of the mathematical disciplines at the University of Vienna in the opening years of the sixteenth century. For a brief
treatment of these interesting gures with a partial list of the books they paid for, see Denis (1782), pp. xixxii.



study of astrology and astronomy would rst work through these

texts. In fact, students in the arts curriculum at the university were
still using this edition well into the middle of the century.54 In all
likelihood, then, Tannstetter had selected Peuerbachs Theorica planetarum nova to lecture on in 1505 and again in 1511.
Beyond these two instances, Tannstetters lectures escaped any
notice in the ofcial records, either the lists of ordinary lectures or
the Acts of the Arts Faculty in general. Tannstetter was active at the
university for nearly three decades, and in that time his name appeared in the lecture lists twice and is mentioned in the Acts and
the matriculation records a handful of times, usually when he
was elected dean of the Arts Faculty or Rector of the university.55
After 1513, Tannstetters obligations increased as he moved into
the Medical Faculty and became Leibarzt to Emperor Maximilian
I.56 Nevertheless, he remained active in the Arts Faculty, regularly
holding lectures on how to use ephemerides. Tannstetters courses
on the ephemerides were popular because they offered immediate
solutions to the many practical problems students encountered
when making astrological calculations, drawing horoscopesespecially nativities, elections and interrogationsand predicting the effects of solar and lunar eclipses.
After covering the information found on the opening pages of an
ephemerides, Tannstetter devoted considerable time to the calculations necessary to convert the data in the almanac to different
locations. In a plain and direct style he introduced each correction
and then explained how to carry out the calculation.57 Tannstetter
divided the remainder of his lectures into two sections, each focusing on a different astrological topic. In the rst section, he concentrated on eclipses and the detailed calculations an astrologer had
to carryout in order to predict the effects of the eclipse. Aping Ptolemy, Tannstetter considered eclipses to be the most powerful of the
common celestial events.58 He had already pointed out that the illustration on the rst page of an ephemerides indicated any eclipses in
the coming year, whether or not those eclipses would be solar or lunar, and how much of the luminary would be occulted during the
eclipse.59 This information, however, was insufcient for making detailed predictions. The astrologer had to note inter alia the latitude of
the moon, the location of the true conjunction as distinguished from
the apparent conjunction, and whether or not an eclipse occurred
near the caput draconis or the cauda draconis.60 Accordingly, Tannstetter provided a number of canons explaining in detail how to calculate this information.61 Here Tannstetter was following Ptolemy,
who had established that all these were important variables that
needed to be considered when making predictions from eclipses.
In the nal part of his lectures, Tannstetter shifted his attention
from eclipses and predictions based on them to judicial astrology
nativities, elections, and interrogations. Judicial astrology required
much more than simply locating the planets in the zodiac. The
astrologer also had to interpret the inuences of those planets
and thus had to take into consideration the motion of a planet
whether direct, retrograde, or stationaryas well as its celestial
latitude, speed, the distance from the earth, and interplanetary aspects or the relative position of the planets to one another. Each of
these variables affected the strength and duration of a planets


inuence on terrestrial events. Tannstetter made these topics the

subject of the next section of his lectures. At the same time, he
introduced a new layer of sophistication, one that relied heavily
on the theories of planetary motion developed by Peuerbach in
his Theorica planetarum nova. Tannstetters detailed explanation
of the observed motion of a planet as the combination of the motions of the center of the planets epicycle and the rotation of the
epicycle itself as well as his explanation of why the moon never
seemed to retrogress came directly out of Peuerbachs text.62
Although the practicing astrologer did not need to understand this
astronomical theoryhe could glean the information he needed directly from the ephemeridesTannstetter implied that an astrologer
who understood why a planet moved in a particular manner was
more competent to interpret the effects of that planet. Other canons
addressed particular celestial variables that affected the planetary
inuence. Some of these could be culled from the tables in an ephemerides, such as the planetary latitudes, but in each case Tannstetter
provided a more thorough discussion of these points and explained
why the astrologer should attend to themonly by knowing the latitude of a planet could the astrologer determine precisely the true
conjunctions between the planets themselves and between the planets and the xed stars as well as their rising and settings with the
xed stars.63 In each canon, Tannstetter was quick to point out
how his exposition relied on Peuerbachs Theorica planetarum nova
and also clearly indicated how and why different variables had to
be taken into account when constructing a horoscope.
While these lectures were primarily a set of practical instructions, they formed an important part of Tannstetters larger project
at the university. In a passing remark toward the end of his canon
for nding the true motions of the sun, moon, and ve planets,
Tannstetter referred his students to his recently published edition
of Regiomontanuss Tabulae primi mobilis.64 This text, along with
Peuerbachs Tabulae eclypsium, offered advanced treatment of the
very topics Tannstetter was concerned with in his lectures on the
ephemerides. Tannstetters remark links these texts to his lectures
at the university and suggest that he might have intended them
for use in more advanced lectures he held at the university. Tannstetters lectures on the ephemerides, then, served perhaps as the
introduction to his more advanced lectures on similar subjects,
and at the least, were conceptually linked to his editions of Peuerbachs and Regiomontanuss more sophisticated and detailed works.
Tannstetters lectures at the University of Vienna were motivated by the pragmatic demands of astrological practice: what
variables did an astrologer have to use and how did he carryout
the relevant calculations. Like Stiborius, he structured his lectures
around the actual tools his students would use as practicing astrologers: the ephemerides that contained the necessary data. Students probably heard his lectures on ephemerides in private
lessons or in extraordinary lectures. When combined with Stiborius lectures on astrolabes, which also occurred in outside the regular curriculum, it is clear that students at the University of
Vienna were could acquire a practical training in astrology. For
the many students who left the university with an arts degree,
the courses offered by Tannstetter and Stiborius provided the

Goldmann (1916), p. 158.

Graf-Stuhlhofer (1996), pp. 7178
Ibid., pp. 7375.
Tannstetter, Georgij Collimitij Dictata in Ephemerides, KBV Vadianische Sammlung, MS 66, fols. 3v16v.
Ptolemy had in his Quadripartitum discussed at length the efcacy of eclipses and how the astrologer should use them in predicting future events.
Tannstetter, Georgij Collimitij Dictata in Ephemerides, KBV Vadianische Sammlung, MS 66, fol. 17v.
The caput draconis and cauda draconis are ascending and descending nodes of the moon. That is, they are the points where the moons path crosses the ecliptic, rst moving
north of the ecliptic and then moving south. The caput draconis and cauda draconis were important, in part, because eclipses can occur at these two points.
Ibid., fols. 16r23v.
Tannstetter, Georgij Collimitij Dictata in Ephemerides, KBV Vadianische Sammlung, MS 66, fol. 26r26v.
Ibid., fol. 27v.
Ibid., fol. 13r.


necessary education to become a practicing astrologer, perhaps

advising a local prince.65 For the students who intended to study
medicine, their education in the Arts curriculum provided a solid
foundation for their medical training. For those students who did
study medicine, they benetted from Tannstetters focus on practical
instruction in his lectures on astrological medicine.

4. Georg Tannstetter and medical astrology

Tannstetter had begun his medical studies in 1508, when he entered the medical faculty at the University of Vienna. Five years later he sought and received a special dispensation from the
bachelors exam.66 After that, he moved increasingly into the Medical Faculty, presumably holding lectures and enjoying the greater
prestige associated with the higher faculty.67 Tannstetter brought
the same concern for practical astrology to his medical writings that
he had shown in his earlier lectures: how could a physician use
astrology in his practice, and why should he bother.
Tannstetter was lecturing on medical astrology by the middle of
the 1520s, and perhaps earlier. It is unclear how often or for how
long he held lectures, but they were collected and printed in
1531 under the title Articium de applicatione astrologiae ad medicinam.68 The famous Viennese physician, Martin Stainpeis offers
some indication of where Tannstetters lectures would have t in
the medical curriculum.69 In 1520, Stainpeis published his Liber de
modo studendi as a guide for medical students at the university. In
this work he suggested a course of study, listed the books that
should be read, and how those books were to be read. Although there
is no evidence that his suggestions were adopted in the Medical Faculty, his Liber de modo studendi probably outlined the general contours of medical education at the University of Vienna. Along with
Galens De criticis diebus, most likely as part of the Articella that
was studied in the rst year, Stainpeis listed astrological works in
the nal three years of study. In the third year of study students
should read Hippocrates Astrologia medicorumon prognostications
based on the motions of the moon and planetary aspectsas well as
his De aere, aquis, locis and an anonymous De astronomia.70 Of particular interest are the texts on using ephemerides and calendars, in the
fth year of study.71 Although Stainpeis did not mention Tannstetter
or his worksthough the two certainly knew each otherStainpeis
musts have been thinking of texts like Tannstetters lectures on ephemerides when he composed his Liber de modo studendi.72
In his Articium de applicatione astrologiae ad medicinam Tannstetter set out to convey the basic tools needed by the learned physician to succeed in his practice. He did not intend to provide long


discussions on the theoretical underpinnings of astrology and its

application to medicine, though he did, when necessary, briey
justify one point or another. Instead, he adopted a didactic format
that presented more complex concepts only after covering the basics and relied on repetition in slightly different words or style to
reinforce a particular point. Tannstetter expected his students to
have a foundation astrology before attending these lectures, and
he assumed that they would be familiar with some of its basic tenets and tools, notably astrolabes and ephemerides. He did not,
however, anticipate that his student would remember the ner
points of astrology, particularly as they applied to medicine.
Tannstetter began with the most basic of tasks: establishing a
correct geniture for the patient. The value of a correct geniture
could not be underestimated. If the physician wanted to claim
any predictive authority, he had to determine his patients natal
horoscope. The physician had to note ve important signs in each
the ascendant for things that affected the body, and the Part of
Fortune, for external matters, likewise the place of the moon for
the disposition of the body and spirit, the place of the sun for
things related to employment, ofces, and honors, and nally
the medium coeli for things concerning actions and authority,
either innate or accepted.73
This natal horoscope would be used in conjunction with a chart
constructed for the advent of any disease in an effort to predict
the course and outcome of that disease. For this reason, Tannstetter
opened his lectures and rehearsed at some length the various methods for rectifying a geniture.74 After determining the precise time for
the chart, the physician then had to determine the horoscopic
houses. Here again Tannstetter was interested only in presenting
the information necessary to accomplish this goal. Rather than engage in a long discussion on how to divide the zodiac into mundane
houses, he recommended that his student use either an astrolabe or
similar instrument from which they could simply read off the horoscopic houses.75 Next the physician then needed to locate the planets within this horoscope and then determine the aspects between
the planets, that is, the geometric relationship between them. To
do this, Tannstetter recommended Regiomontanus Tabulae directionum.76 While Tannstetter was recommending the most accurate
tools availableno doubt in an effort to improve the physicians
prognoseshe was also encouraging the physician to surround himself with a set of tools that would convey authority.77 Just as Stainpeis had implied in book six of his Liber de modo studendi where he
discussed the day-to-day practices of a physician, a physician who
was surrounded by technical instruments and reference manuals

Michael Shank suggests that by the fteenth century, Habsburgs princes increasingly relied on astrological advisors who were not also practicing physicians. However, it
seems difcult to generalize. Tannstetter was, himself, a member of the medical faculty for much of his career and personal physician to Emperor Maximilian I. Monica Azzolini
has found that in Milan, at the end of the fteenth century, the Sforza dukes continued to consult astrologer-physicians. For Shanks claim, see Shank (1997), esp. pp. 254255; see
also Azzolini (2005, 2008).
Tannstetter matriculated on 10 May 1508 (Schrauf, 1904, p. 68). His request for exemption was in 1513 (ibid., p. 84).
In the Germanies, it became increasingly common through the sixteenth century for academic astrologers to hold appointments in the medical faculty (see Westman, 1980,
esp. pp. 118119).
Tannstetters lectures were printed in 1531 in Strasbourg. Graf-Stuhlhofer has suggested that these lectures were delivered in 1526/1527 (Graf-Stuhlhofer, 1996, p. 147).
On Stainpeis, see Pawlik (1980), Durling (1970), Khnel (1965), pp. 8486; Crystal (1994), pp. 218219.
Stainpeis (1520), fols. 20r, 20v, 21v.
Ibid., fols. 7v, 16v. On the Articella in the medical curriculum, see Demaitre (2003). On Galens De criticis diebus, see OBoyle (1991).
In 1521, Tannstetter had recommended Stainpeiss receipe as a means of warding off the plague (Tannstetter, 1521, sig. B2r).
Et quanquam quolibet anno tota clestis gura alicuius nativitatis dirigi possit & debeat, sunt tamen 5. signicatores, quos prcipue & singulariter iubet Ptolemus dirigi
verbo 77. sui Centilo. scilicet ascendens pro his qu corporis sunt, & gradus partis fortun, pro bonis externis. Item gradus pro corporis animque dispositione. Gradum pro his
qu ad dignitates, magistratus & honores pertinent. Ultimo medium cli, pro ijs que actiones, magisteria, articia, sive ofcia concernunt (Tannstetter, 1531, fol. 7v).
Ibid., fols. 3r5v.
Ibid., fol. 6v.
Ibid., fols. 7v8r.
Roger French argues that one of the primary reasons learned physicians incorporated predictive astrology was to compete in a medical market place by attracting patients
with their technical apparatus (French, 1996, esp. p. 475). This claim form an important part of his general argument in French (2003).



and consulted both an astrolabe and Regiomontanuss detailed

tables of planetary motions would have instilled condence in his
patients.78 This certainly was seen as an advantage when trying to
attract and retain patients in the increasingly competitive medical
market place.
At this point, Tannstetter shifts his attention to calculating the
critical days and offers a critique and correction to Galens method.
He opens by pointing to the importance of the moons motion in
determining critical days. This leads him to confront the problem
of the two types of months and which is applicable to medicine.
Tannstetter repeated the great medieval physician Pietro dAbano
when he explained that the medical month, measured from the
point that the moon rst becomes visible after a new moon, is
problematic because sometimes it is visible on the second day after
the actual new moon, sometimes the third day. This variability carries over into the physicians attempt to determine the critical
days, which will all vary depending on the moons rst visibility.79
Tannstetter claimed this argument for his own, though it too was
found in dAbanos Conciliator.80 Tannstetters contributition was to
explain why the moons motion was irregular and thus why in some
months the rst visibility occurred on the second day, in other
months on the third day, and occasionally on the fourth day.81 The
point of his discussion was to introduce a different method of calculating the critical days. Tannstetter claimed that although Galen was
correct to use the moons motion to determine the critical days, he
had incorrectly relied on the mean motion of the moon rather than
on the true motion. Fortunately, Regiomontanus had restored the
true motions and had rst shown how the critical days were related
to the true motion of the moon. This method, Tannstetter assured his
students, avoided the problem of the rst visibility that plagued the
more common calculations.82 Clearly Tannstetters discussion of critical days builds on his previous lectures in which he taught his students how to use the ephemerides to calculate the moons actual
Tannstetters theoretical discussion about critical days laid
foundation for his practical instructions: explaining how to construct a special chart to determine the critical days and how to
use the chart to predict the course of an illness. Tannstetters chart
resembled a horoscopic chart with sixteen rather than twelve
houses. Tannstetters chart was simply an adaptation of Ptolemys
claim in the Centiloquium that the critical days could be determined by calculating the moons position on a sixteen-sided gure.83 The rst task was to determine the true location of the
moon at the moment the disease rst appeared and to record it in
the rst location in the chart, analogous to the ascendent. From this
rst location the physician could calculate subsequent critical days,
when the moon had traveled one quarter of the way around the zodiac. From this chart the physician calculated the moons position in
the zodiac during the progress of the disease. The physician then
used a calendar or ephemerides to correlate the moons location in
the zodiac at the four cardinal points of the chart, analogous to the
cardinal points in a typical horoscope, to the actual date. Tannstetter


claimed that by using this gure and an accurate calendar, the physician could determine the true critical days for any disease.84 Having identied the true critical days using Tannstetters more precise
technique, the physician then turned his attention to the patients
horoscope and the effects of the individual planets and inter-planetary aspects. To assist the physician in this process, Tannstetter provided a concise list of favorable planets and inter-planetary aspects
and concluded the section with lists ranking the favorable horoscopic houses, planets, and aspects.85
Tannstetter linked his lectures on astrological medicine to those
he had given in the arts curriculum by applying many of the same
techniques to the physicians practice. In addition to his instructions about how to use ephemerides to calculate the true motion
of the moon and then to correlate the position of the moon to
the day of the year, Tannstetter introduced eclipses as another
important tool physicians could use to predict the course and outcome of a disease. Although eclipses did not occur every year, if an
eclipse had occurred, the physician needed to take it into account
when making his prognosis. Tannstetter explained that the physician needed to determine the lord of the eclipse in order to understand what effects the eclipse would have. Tannstetters list of
favorable planets served as a handy reference here. Moreover,
the physician had to determine the magnitude of the eclipse in order to understand the severity of its effects.86 Along with predicting
the general effects, Tannstetter tried to give the physician a set of
prognostic tools to decide when the disease was going to cause the
patients death. Tannstetter pointed out that it was important for
the physician to know when a disease was beyond his control, for
he harmed his own reputation and that of the profession when he
tried and failed to cure patients.87 The professional realities of medical practice played an important part in Tannstetters lectures on
medical astrology.
Yet another way Tannstetter linked his lectures on medical
astrology to his arts lectures was through his frequent recommendations that physicians use an astrolabe and astronomical tables to
determine the relevant astrological information. In addition to his
own lectures on ephemerides, Tannstetter could have been referring to those of his student, Andreas Perlach, who took over the lectures on ephemerides in the late 1510s. Because most of the
students attending his lectures on medical astrology would have
heard lectures in the arts curriculum, Tannstetter could be condent that they would be familiar with ephemerides and how to
use them. Likewise, when he encouraged his students to use astrolabes or other instruments, he was relying on a strong local tradition in the Arts Faculty to develop and lecture on various
astronomical instruments, exemplied in Stiborius lectures. Stiborius and Tannstetter may have even coordinated their lectures.
Stiborius regularly drew attention to the medical applications for
his various instruments, telling his students how to color their
astrolabes to make it easier to determine the motions of the humors.88 Tannstetter often encouraged his student to use astrolabes
and similar instruments, some of which were modied specically

Stainpeis (1520), fols. 102v111v.

Tannstetter (1531), fols. 29v31v.
Ibid., fol. 31v. See Siraisi (1990), pp. 135136; French (1994), pp. 5053.
Tannstetter (1531), fol. 31rv.
Ibid., fols. 32v33r.
Cum igitur Ptolemaeus inter Aegyptios, immo omnes Astrologos princeps, . . . scribit enim 60. verbo haec verba. Super aegrotis Criticos dies inspice, ad peragrationem in
angulis gurae 16. laterum (ibid, fol. 33r).
Ibid., fols. 33v34v.
Ibid., fols. 36r37r.
Ibid., fols. 37v38r.
Ibid., fols. 39v46r. On the importance of predicting the death of a patient, see Siraisi (1990), pp. 133136. On the problems physicians faced when their medicine seemed to
fail them, see Arrizabalaga, Henderson, & French (1997); French & Arrizabalaga (1998).
For example, Stiborius points out that the astrolabe should be colored to correspond to the motions of the four humors in his canon Mociones 4or humorum (Stiborius,
Canones astrolabij, BSB Clm 19689, fol. 75rv).


for medical use.89 Tannstetter recognized that the point of medical

education was ultimately practical.90 Consequently he focused on
the actual tools and applications for astrology in medical practice
rather than theoretical topics.


quently, close study of the astrological curriculum at the

University of Vienna is important not only for what that curriculum
reveals about the practical methods of teaching astrology but also for
how that curriculum inuenced astrological education and practice
throughout the Germanies.

5. Conclusion
Stiborius unpublished lecture notes along with Tannstetters
published and unpublished lectures begin to reveal the shape
and content of the astrological curriculum at the University of
Vienna. Although this curriculum has remained obscured by a lack
of evidence in the ofcial documents, their lectures indicate that
the University of Vienna incorporated some of the innovations of
its famous fteenth-century faculty. Peuerbachs Theorica planetarum nova, the most important introductory astronomy textbook,
and a number of Regiomontanuss texts were central to Tannstetters lectures on astrology. Regiomontanuss efforts to establish
an astronomy and astrology that benetted from the development
of technical astronomical instruments seem to have been realized
in Stiborius teaching. Perhaps more interesting are the links between Stiborius and Tannstetters lectures. The two colleagues recognized their teaching activities as related and complementary,
and together shaped the astrological curriculum so that it was
based on detailed mathematics and astrological instruments. Their
interests and lectures informed the education of students in the
arts as well as medicine at the University of Vienna during the rst
two decades of the sixteenth century.
The curriculum at Vienna was affected the practice of astrology
well beyond the walls of the city. Locally, Andreas Perlach heard
lectures from both Stiborious and Tannstetter and later worked
with them. Perlach then continued many of their practices when
he became a master in the Arts Faculty. His lectures on the ephemerides were collected into a book and published in 1551. They
seem to have remained the core text on ephemerides at the university until the middle of the century. Another student, Johannes
Vogelin heard lectures from Tannstetter and Perlach. He wrote an
important judicia on the comet of 1532. In his judicia Vogelin published his observations of the comet and recorded the parallax he
claimed to have measured. Vogelins observations were at the center of a debate between Tycho Brahe and Christoph Rothman about
the comet of 1577.91 Other students studied at Vienna and then returned home, taking with them the education they had gained while
at the university. Joachim Vadian studied and taught at the University of Vienna during the rst two decades of the sixteenth century,
and while there he heard Stiborius lectures on astrolabes as well as
Tannstetters on ephemerides and medicine. He took his lecture
notes with him when he returned to St. Gallen, where he was appointed the city physician. He probably used those lecture notes in
his practice as the city physician. Jakob Milich was another student
at Vienna who heard Tannstetters lectures on medicine. After leaving Vienna Milich moved to the University of Wittenberg where he
wrote a commentary on book two of Plinys Historia naturalis.
Milichs text shows considerable debt to Tannstetters own commentary on book two.92 In some cases, the inuence of the astrological
curriculum can be traced through texts that were copied and taken
to distant cities. In one instance, an anonymous person was so interested in Tannstetters Articium de applicatione astrologiae ad medicinam that he had the entire text copied by hand and returned to
Wratislavia.93 As these examples suggest, the astrological curriculum at Vienna spread beyond the university and the city. Conse89

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