astronomy in carolingian schools

8/10/2019 Astronomy in Carolingian Schools

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ALTERNATIVES TO PTOLEMY:ASTRONOMY IN CAROLINGIAN SCHOOLS

Wesley Stevens

As a humanist, I wish to discuss astronomy and some other aspects of science in Europe during the middle

ages1. But was there any real science in those tumultuous times?

Actually, my studies focus on perhaps the worst of times, the sixth to eleventh centuries after Christ in theLatin est. ell!educated people always as" whether the #ar" Ages were a $ad time for science. %f course itwas a $ad time& After all, it was the period after the 'oman soldiers and lawyers and tax collectors hadwithdrawn and $efore the new universities arose in estern Europe. I $elieve that we might do without taxcollectors, $ut we cannot do without universities. (igure ) will suggest how the world loo"ed in the early middleages, yet that is not the same way that contemporary maps of Asia* EuropeAfrica appear. +his evidencesuggests that the world was round in A.#.--, $ut that a$out )-- it must have $een flat& +hat conclusion is only

preliminary and must $e reviewed.2+he part which interests us here is western and central Europe, especially

the Carolingian Empire.

)+he author is grateful to the /umanities 'esearch 0roup of the 1niversity of indsor for inviting him to present this paper inits #istinguished 2pea"er 2eries on 3- 2eptem$er ). /e also expresses appreciation for the Board of Board of 0overnorand officers of the 1niversity who support the /umanities 'esearch 0roup and this lecture series. It is an example ofacademic integrity which other universities could well follow. +he idea of this paper was first offered on )4 5uly )6 at the7ymphen$urg 8alace 9:;nchen< to guests of the Alexander von /um$oldt!2tiftung sponsored also $y the 2iemens!2tiftung.2everal stages of its development were presented to the #epartment of 8hysics of 0uelph 1niversity, the Early :edieval2eminar of the Institute for /istorical 'esearch 9London


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+he pu$lic "nows with unwonted certainty that the dreadful 0ermans invaded estern Europe and destroyedall good things, the 'oman Empire fell, and then came many wars. +his opinion is often offered $y researchprofessors in our universities. /istorians however do not usually agree with the pu$lic, including some of theirvociferous colleagues. +oday, historians throughout the world recognise that wars and taxes, plagues andfamines occur in every period, and the dar"est age is usually the current one. +hey emphasiDe that in the sixthcentury most of the new immigrants came into the western lands peacefully, and that many had $een invited

$ecause of the s"ills they could $ring.3

0oths, Alemanns, Bavarians, Burgundians, (ran"s, Angles, and 2axons came est in order to settle andfarm. +hey $uilt houses, $arns, mills, and $ridges. +ogether with earlier local inha$itants, they created mar"etsand new cities li"e :unich and 8aris which did not exist $efore. A good and healthy life was possi$le for them at

that time. +he population increased steadily in all areas of Europe from the sixth to the thirteenth century. 4 A

part of the increase and the well $eing in the early middle ages came with the new immigrants. (rom the sixth toeleventh century, - percent of the people of all races were peasants who raised grain, herded cattle, shovelledmanure, and dug their gardens. In Europe the origin of schools came specifically from the demands and thesupport of farmers.

+he (ran"s were diverse 0ermanic tri$es that immigrated to middle and western Europe during the fifth andsixth century. +here was a particular family called =arolinger.= +he Carolingians settled in the lands whichtoday are "nown as the 7etherlands, Belgium, and Luxem$urg, and they also moved up the 'hein into regionsaround :etD and o$lenD. (rom this family in the eighth century came a "ing of the (ran"s, "nown to us as arlder 0roFe or Charlemagne. /e, his son, and four grandsons $ecame the greatest patrons of schools and

li$raries in the history of Europe. 2ee (igure G.

3Bernard Bachrach, Merovingian Mlitary Oganization,9:inneapolis 1niversity of :innesota 8ress, )HG


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arl der 0roFe ruled the (ran"s from H to )6, during which time he received diplomats from Istan$ul,Cairo, and aragoDa. /e attracted scholars to his court from England, Ireland, 2pain, Italy, and Austria. 7ot onlydid he as" the $ishops and a$$ots within his rule to develop schools and give them guidelines for doing so, $uthe also gave large amounts of land for support of schools and li$raries. +hat active and continuous interest setan example which led his faithful officers to give yet more lands under their control to support them, too.

2chools always re>uire organised, continuing support. In the ninth century the only institutions with sufficientsta$ility to support schools and li$raries were the cathedral churches and monasteries. Bishops needed to trainstudents to $ecome priests for service in parish churchesJ and mon"s wanted to leave the $usy life of family and

mar"ets in order to form communities for prayer, reading the /oly 2criptures, and singing the praises of theCreator. +hey formed communities to wor" and to pray together, as 2t Benedict said. But this leaves us with apro$lem.

e "now that priests and mon"s learned to read and write. +hey learned Latin $y reading Kirgil and Cicero, inorder to understand $etter the $i$lical literature. +hus, it seems today that the education of medieval mon"s musthave $een rather limited, fixed upon the Bi$le, and restricted to a low intellectual horiDon. ould young mentraining to $ecome priests and mon"s also analyse earth and water, air and s"y? ould they develop the s"illsneeded for understanding and coping with our natural world? ould they study arithmetic and geometry? If weexpect not, we would $e mista"en. Amongst the $i$lical, liturgical, and grammatical texts which survive inmedieval Latin manuscripts, we also find scientific texts and diagrams. hat did those schools actually teach?

%ne of the most studied su$ects was the computus, for which the English word is calendar rec"oning. Atleast nine thousand medieval Latin manuscripts survive today which contain essays and ta$les of data a$outcalendar rec"oning. 2ome modern codicologists estimate that for every surviving manuscript, perhaps fifteen

have $een lost. +hat indicates a large num$er of computistical texts given the >uestion of setting the date ofEaster in any year and proecting the dates of future Easters. It was a religious need to $e met in a reasona$leway with all the resources of science.

Every calendar of every culture must rec"on every year on the $asis of the course of the 2un or the course ofthe :oon, in order to anticipate recurring dates and cele$rate important feasts. +he first Christians were 5ewswho used a lunar calendar, in order to determine the date of 8assover. 5esus cele$rated the 8assover $efore hewas arrested and "illed. 5ews and Christians lived however in the 'oman Empire which used a solar calendar.Its $eginning point was the founding of 'ome, from which other dates were rec"oned. Christian scholars tried to$ring the lunar and solar cycles into coordination, $ut without success. It loo"ed li"e a pro$lem which would $eeasy to solve, $ut in fact it has still not $een solved precisely even today.

#id you "now that the year ) ended on 3) #ecem$er with its final minute elongated to sixty!one seconds?According to the agreement first organiDed $y the Bureau international des poids et mesures, since )4 5an )d

-hall cloc"s have $een regulated $y International Atomic +ime, a system which is $ased upon a new definition of

one second determined $y resonance fre>uency of Cesium atom )33. +hen, the proper num$er of seconds areadded up to complete each year. 1nfortunately, $ecause deterioration of the Cesium atom cannot "eep up withrotation of the Earth, an adustment of an extra second is re>uired at least once every fifteen to eighteen

months.52omehow, as it is "eyed into atomic physics and despite exceptions and irregular adustments, that

system is supposed to $e more scientific than the old way of measuring time $y or$its of 2un and :oon withtheir exceptions and irregularities. 2ome of us may suspect that such claims to science may $e merely adifference of perspective.

+he possi$ility of coordinating the lunar and solar cycles in order to ma"e a proper calendar however wasattractive to priests and mon"s whose studies went well $eyond the needs of prayer and /oly 2criptures. +heywere stimulated to study mathematics and astronomy in monastic schools. hat sort of mathematics is found inthe Latin manuscripts from those schools?

+he Calculus of Kicturius of A>uitaine was used and commented upon $y masters in those schools, whichmeans that arithmetic, as we "now it today, could $e learned. Added to that during the ninth century wasBoethiusMArithmetica, one of whose sources was the arithmetical $oo"s of EuclidMs Elementa!!, !!!,and !"the $est availa$le arithmetic. 2everal school$oo"s survive which actually show pro$lems which school masters

4+he current time!"eeping system is operative at the 1 2 7aval %$servatory, 364- :assachusetts Avenue 7 , ashington,

# C. +he Cesium atom system was once duplicated $y the 'oyal 0reenwich %$servatory at /erstmonceux Castle, /ailsham91


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set for their students, some of which were still used in my own school wor" in arithmetic and alge$ra.6

8lane 0eometry is often found in early Latin manuscripts of Christian schools. +he masters taught the first

four $oo"s of EuclidMs Elements.7+his geometry serves no pious purpose, $ut the mon"s in many schools were

o$viously interested, and you may well guess why that was so 8lane 0eometry served $asic needs of adeveloping nation. It survives as part of a large collection of texts, gathered and used $y surveyors andengineers trained in those same schools.

But what a$out astronomy? 1nfortunately, most wor"s of 0ree" astronomers were not "nown in Latin, save

for very few and very short excerpts. +he wor" of Eudoxios 96-!344 BC


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Indeed, there were several other ways in which the availa$le astronomical data would also ma"e good sense.%ne of the early 0ree" models of planetary or$its was an interactive system of nested or$s represented asconcentric circles with the earth as centre 9(igure 6uenceof planets in their distances from the Earth. Another 0ree" model which survived in (ran"ish schools displayedthe relative distances $etween or$its, that is, harmonic intervals of older style 8ythagoreans which they calledtones or tonal intervals of or$its.

Aristotelian se>uences and 8ythagorean intervals could $e visualised in terms of concentric circles, and it isfrom those well "nown diagrams that an idea was created in modern times that during the :iddle Ages allastronomers thought that the or$its of planets were circular and centred on the Earth. +he ninth century


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diagrams however may not $e fitted into those more recent assumptions.ou may wish to loo" up at the heavens tonight, wherever you may $e, and then return each night or two for

a$out one month. 1sually, you will discover one or more very $right planets wandering among the other $rightstars. 2ome planets not only rise and fall with the other starsJ they are easily o$served to wander $ac" andforth. If you go out into the countryside the entire heavens will open up their riches for you. atching the planet:ars, night after night, you will o$serve its irregularities, and you can map out the resulting data on that scalewhich is called the odiac. (rom the restricted s"ies seen from some city apartments, you may even do it withKenus $ecause it is so $right and so easy to locate. :ercury is always near the horiDon where light distortion, if

not low lying clouds, seldom allow any series of o$servations.(or example at the end of twilight in mid!5anuary ), the :oon is in waxing crescent and will not give much

light, thus allowing you to see $etter. At sunset, Kenus could $e seen $riefly in the 2outhwest at GG-o, $ut only)Goa$ove the horiDon. 5upiter will $e near Kenus and G oa$ove the horiDon. Loo"ing due 2outh, 2aturn will $e

)3oto the East and 6ohigh.8

In the early ninth century, many diagrams show the motions of :ercury and Kenus turning a$out the 2un astheir centre, while the group of three planets circles the earth together.9(igure 4a< +wo such diagrams were"nown in schools on the 'eichenau one shows the earth!centred circle of only five planets with two 2un!centredcircles of Kenus and :ercuryJ the second displays only Kenus and :ercury on circles moving a$out the 2un.%ne circle is distorted in order to show its inclination from the plane of the 2unMs or$it. %ther diagrams showedall three planets on separate centres, as their or$its were studied. 9(igure 4$


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+wo other types of manuscript drawings will also demonstrate that cycles of the planets did not re>uire theEarth as centre. In the early ninth century the masters analysed the spatial relations of planetary apsides inapogee and perigee. 9(igure a< Apogeeis the greatest dis!tance of the planetary or$it from the Earth during itscycleJ erigeeis the least distance.


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#eviation in latitude from the ecliptic path of the 2un was also newly diagrammed. %n the next drawing ofplanetary latitudes, the odiac was first drawn and then the planetary paths placed upon it. 9(igure $< It isdifficult to pic" out the paths of the planets until you notice that the motion of each one incorporates anelongated, reversed . Carolingian masters lac"ed a general concept of epicycles, as used $y /ipparchos or8tolemy, $ut they could represent the phenomena of apparent stations and retrogradations for each planetaryor$it with that Dig!Dag notation.


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+he :oonMs extreme deviations are seven parts of latitude a$ove and five parts $elow the ecliptic $y whichthe $readth of the Dodiacal scale is defined. +he ecliptic itself was a theoretical construct a line along which ornear which the 2un moved daily. (or Carolingian scholars as for 0ree"s and 'omans, the 2un seemed to movein a path which wavered in a range of oneparsor step of latitude a$ove or $elow that circle. All other planetarylatitudes could $e read within this scale of the odiac, $ut on occasion Kenus passed $eyond it $y one or eventwo steps.

2ectors of the Dodiacal scale are always shown from the o$serverMs positionJ $ut donMt $e misled $y that.8roection of planetary latitudes on the odiac gives the appearance of roughly concentric or$its, $ut in fact theor$it of each planet has its own centre which may not $e clear from the reproduction in (igure $ $ut which you

would $e a$le to pic" out easily on the manuscript folio itself.+hese drawings of apsides and latitudineswere not physical images of reality of course $ut were a$stract

representations of theoretical elements of Astronomy. +he Earth was the point of o$servation $ut often was notshown on diagrams of or$ital apsidesor latitudines. Except for 2un and :oon, the Earth was usually not thecentre of the or$its, contrary to 8tolemy.

2ome of these ideas a$out the stars in the heavens could also $e of interest to wealthy patrons. Puite an

elegant manuscript10was prepared a$out A.#. 3-!6- either at Aachen in the court of Ludwig der (romme

9)6!6-< or perhaps at Ingelheim in the court of his $eautiful Bavarian wife, 5udith 9)!63< where Ludwig

10Arates.*Nach%ildung der 3andschrift Ms oss. 4at.5.67 der 1i8/suniversiteit 4eiden* 9LuDern (a"simile Kerlag,

)H*)


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made his home. +he Leiden codex features Dodiacal signs and other star!groups represented $y handsomecoloured drawings of the heavenly figures drawn from the popular /ellenistic myths, in order to help the viewerremem$er star positions and locate them in the s"y.

+hese manuscript illuminations were in glorious colour, with stars applied to the parchment in gold leaf. Butthe su$stance should not $e ignored, for this very expensive $oo" also includes some of the astronomicaltheories and constructs which were studied in the Carolingian schools. +he technical drawings seen earlier infigures 4 and were here com$ined into a single planetary configuration created $y an astronomer. 9(igure Huence of or$its and a$out intervals $etween them. :asters andstudents in the ninth century however developed much more complex theories for apsides, latitudes, epicycleson the sun, and varying inclinations. +hey could see that 2un and :oon circled the Earth. %n the other hand,they could also see that, while five other planets or$ited the Earth, their or$its were not Earth!centred.

It would $e difficult to $elieve that Carolingian scholars contri$uted so much new astronomy without anywor"s of the 0ree"s to guide them. But also, how could they do it without instruments which would allowimproved o$servations of the heavens? Let me remind you therefore that the odiac itself was a standardised

))'eferring to ms Leiden f.3v, :osterts 9)-< said that =...the configuration, and pro$a$ly the manuscript, can $e dated l,

around ) :arch.= 1nfortunately, the evidence for this assertion is not entirely consistent or verifia$le.


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%ther scholars during the tenth century were a$le to reason that the vernal e>uinox fell not on G) :arch $ut as

early as ) or )H :arch. Before A.#.)-, ilhelm von 2t. Emmeram created a new instrument for astronomicalo$servation at 'egens$urg and esta$lished true solstices and e>uinoxes. 9(igure < ith his Sphaera, magisterilhelm could date the vernal e>uinox on ) :arch, a correction $y five days, truly a remar"a$leaccomplishment. ilhelm soon $ecame a$$ot of /irsau 9)-H)!)-)< where he played an important role inreform of feudal $ishops and their accumulation of properties $ut could not continue this astronomical wor",

though many others did so, for example 2ige$ert 9ca.)-3-!)))G< who taught at 0em$loux and :etD. 18ith

63!.18

ilhelm von 2t. Emmeram und /irsau in ms :;nchen 2taats$i$liothe" CL: )6 92t. Emmeram s.RII< f4!Hv. 2ee

further 2ige$ert of 0em$loux, 4i%er decennalis, ed 5 iesen$ach, :onumenta /istorica 0ermaniae. Puellen Dur0eistesgeschichte des :ittelalters, )G 9:;nchen :0/, )


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improved methods and o$servations in many schools, :arian 2cottus 9)-H!)-G*3< was ustified in calling for

calendar reform when he attracted students and other magistri to (ulda and Qln. 19

+his essay has called attention to studies of computus, arithmetic, geometry, and astronomy in early medievalschools. (ran"ish teachers used Aristotle very little, they did not follow 8tolemy, and their astronomy was notderived from a literal reading of the Bi$le. Boo"s were scarce, $ut intelligence was plentiful. (rom the fewsources availa$le to them, Carolingian scholars made something new in science concerning accurate solsticesand e>uinoxesJ they introduced to western Europe the astronomy of planetary or$its, eccentric to the EarthJ and$etween regular times of prayer they invented new methods and a series of new instruments which were usedfor o$servation and which allowed the creation of improved scientific theories. +hese are aspects of humancreativity in the early :iddle Ages which humanists sometimes forget $ut which all of us may appreciate.

ACKNOWLEDGEMENTS

+he pu$lisher and author express their appreciation to the following pu$lishers and li$raries for permission to reproducemanuscript pages, drawings, and printed maps Alfred nopf 8u$lishers 97ew or"

astronomy in carolingian schools

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