A Medieval Planetary Diagram in Graz University Library

IntroductionThe manuscript MS 38 in the manuscript collection of the University Library in Graz, Austria, has as its main component a Biblia sacra Veteris Testamenti cum prologis Hieronymi. The codex is part of a series that includes two volumes catalogued as MS 37 in the same library and CVP 1 1 80 in the Austrian National Library. The series was in the possession of Stift Neuberg an der Miirz, Austria, until its suppression by Emperor Joseph ? in 1786. This monastery had been founded in 1327. For palaeographic reasons1 the writing can be dated to the twelfth or early thirteenth century. The text therefore is older than the monastery and hence must have been brought there from another location.The binding of the codices was carried out in the fifteenth century in Neuberg.2 For MS 38 a single folio of parchment was used as a flyleaf. It is inscribed on both sides, but the text has no relationship to the rest of the volume. Obviously the bookbinder chose this folio only for its suitable size, which is rather large (c. 45cm high, 31cm wide). From traces on the now exterior margin it can be concluded that the folio was at one time glued to others inversely compared to the present state, i.e. what is now the recto side was once verso. The present recto (the meat side) at that time was clearly empty of text or drawings, suggesting that the folio was the last in a codex (or at least in a major section). It carries several notes regarding coins, measures, and weights, and a verse to commemorate the names of the books of the Bible. All these texts are ascribed to the fifteenth century, i.e. the time of the binding.On verso (hair side) there is a text from Beda Venerabilis's De natura rerum, surrounding a circular diagram (Figure 1). It is followed by an explanation of the various forms and meanings of the word 'vesper' and an account of the Greek numerals taken from Beda's De temporum ratione. These texts and the diagram have been ascribed to the twelfth century.The diagram shows a peculiar drawing of the universe. It combines the Macrobiantype3 display with an Isidore-type TO-map,4 a presentation of the geographical directions, and a sketch of a lunar eclipse. From a detailed microscopic study of the folio it can be concluded that the drawing sequence was as follows. First the circles were drawn. Next the vertical line (north-south) was inscribed. Then the text was written (probably starting from the outer rim and proceeding inwards) and the central map drawn. Finally the horizontal (east-west) line was drawn. Thus it seems obvious that the drawing was made in a single action, and that the rather disparate elements were drawn at one time and not added later on. The quite unusual combination of elements opens an interesting view on the astronomical practice in monasteries of the twelfth century.The Accompanying TextThe text surrounding the planetary diagram reads:Inter terram celumque VII sidera pendent & certis discrepatus quae vocantur errantia. contrarium mundo agentia cursum. id est. levum. ilio semper in dextera praecipiti. & quamvis assidua conversione: inmense celeritatis. attollantur ab eo rapiuntur in occasus adverso tarnen ire motu per suos queque passus advertuntur.nunc inferius nec superius propter obliquitatem signiferi vagantia. Rathis autem solis praepedita anomala, vel retrograda, vel stationaria fiunt.Between Earth and Heaven 7 stars are suspended at certain distances and these are called wanderers. They are running their course contrary to the world that is to the left of it, always to the right of the precipice. And although by a perpetual revolution of immense celerity they are raised and carried to the setting, they nevertheless are perceived to go in adverse motion, everyone by its pace,straying once higher, once lower because of the obliquity of the sign-bearer. But hindered by the rays of the Sun they become abnormal, or retrograde, or stationary. …