STEVENS Wesley M - The Figure of the Earth in Isidores de Natura Rerum

The Figure of the Earth in Isidore's "De natura rerum"Author(s): Wesley M. StevensReviewed work(s):Source: Isis, Vol. 71, No. 2 (Jun., 1980), pp. 268-277Published by: The University of Chicago Press on behalf of The History of Science SocietyStable URL: http://www.jstor.org/stable/230175 .Accessed: 01/09/2012 15:11

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NOTES & CORRESPONDENCE THE FIGURE OF THE EARTH IN ISIDORE'S "DE NATURA RERUM"

By Wesley M. Stevens*

D uring the Hellenistic, Roman, and medieval periods, descriptive literature concerning the cosmos almost uniformly discussed the earth as a globe and the

heavens as a sphere.' This literature, often intended for school instruction, was sometimes accompanied by stylized diagrams depicting the globe. The diagrams are of three types: the globe divided both horizontally and vertically into four parts by waters and their projections; the globe with parallel lines representing three, five, or more zones of klima (or latitude); and the globe with the three partially known continents of the oikoumene extended over the entire surface.2 Such diagrams may be inferred from early texts in various languages and from various periods, but with the Babylonian exception mentioned later, the diagrams themselves do not survive until examples belonging to the seventh, eighth, and ninth centuries of our own era.

The earliest extant diagram of the earth as a globe occurs in manuscripts of the De natura rerum by Isidore of Seville, a schoolbook intended to outline the organized knowledge proper for an educated man in seventh-century Visigothic Spain. It is a diagram of the third type, known as rota terrarum or orbis terrae. Inexplicably, given its importance, it has suffered comparative neglect, as a brief comparison of its place in the manuscript tradition with its recent publishing history will make clear. The neglect may relate to two problems-the assumption that Isidore did not conceive of the world as a sphere, and the assumption that the rota represents a disk and not a sphere. The rota terrarum however displays a more sophisticated conception of the world than has often been acknowledged. Occurrences of reversed rotae in some of the later English manuscripts of De natura rerum and other Latin works have similarly been ascribed to error. A reconsideration of the Isidorean rota in the context of Greco-Roman depictions of the globe should correct these misapprehen- sions.

A two dimensional representation of three dimensions is by its very nature prob- lematic. Thus in the absence of primary literary evidence, the clay tablet from the seventh or sixth century B.C. found in ancient Sippar in southern Babylonia-the

*Department of History, University of Winnipeg, Winnipeg R3B 2E9, Canada. My research was undertaken with support from the Social Sciences and Humanities Research Council

of Canada (formerly The Canada Council) and the University of Winnipeg. ' A. P. Newton, "The Conception of the World in the Middle Ages," Travel and Travellers of the Middle

Ages (London: Routledge & Kegan Paul, 1926), pp. 1-18. The relevant Latin texts have also been reviewed by F. S. Betten, "Knowledge of the Sphericity of the Earth During the Earlier Middle Ages," Catholic Historical Review, 1923, N.S. 3:74-90; by J. K. Wright, "Early.Christian Belief in a Flat Earth," in his Geographical Lore of the Time of the Crusades (1925; reprint New York: Dover, 1965), pp. 53-54, who nevertheless suspected that some believed the earth to be flat like a disk rather than spherical; and by Charles W. Jones, "The Flat Earth," Thought, 1934, 9:296-307, whose copious references to the earth's sphericity in medieval literature of all centuries left no such doubts. See also D. R. Dicks, Early Greek Astronomy to Aristotle (London: Thames & Hudson, 1970), pp. 21-22, 72, 177-178, et passim; Germaine Aujac, "L'image du globe terrestre dans la Grece ancienne," Revue d'Histoire des Sciences, 1974, 27:193-210.

2Especialiy valuable is the list of manuscript and facsimiles provided by Marcel Destombes in Mappe- mondes, Vol. I of Monumenta cartographica vetustioris aevi, A.D. 1200-1500, ed. R. Almagia and M. Destombes (Amsterdam: N. Israel, 1964), esp. Ch. II, although the earliest examples were not reproduced. ISIS, 1980, 71 (No. 257) 268

ISIDORE'S FIGURE OF THE EARTH 269

earliest extant figure said to represent the shape of the earth and the heavens-has been described as displaying a disk floating on a cosmic sea.3 Evidence of this concept is lacking however from any other Mediterranean people, for example, the Egyptians or Hebrews. Among the Greeks no surviving fragment of pre-Socratic writings re- quires the notion of a disk-shaped earth, though some modern scholars have accepted ascriptions of the disk or tambou- rine shape to certain of the pre-Socratics in the later doxographical literature.4 The dominant Greco-Roman tradition, however, is of a spherical earth. Attributed first to the fifth-century Pythagoreans Parmenides and Empedocles, the concept of the earth as a globe was accepted and promoted by Plato, Eudoxus, and Aristo- tle; it more or less drove out all other concepts in surviving Greek and Latin literature.5 In consequence, the surviving Latin manuscripts containing Hellenistic, Roman, and medieval illustrations of the whole earth all depict a sphere.

Extant representations of the earth projected on a circle are of three types. The

0

tEP OIX0 0

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Figure 1. The orbis quadratus ascribed to Krates of Mallos.

first is an ancient orbis quadratus similar to one often found in Etruscan and other Mediterranean designs. Its earliest indisputable scientific use was attributed by Strabo to Krates of Mallos, a scholar at Pergamum during the second century B.C.6

He was said to have projected a globe with four continents divided by great rivers or oceans. Euro-Asia and all the Mediterranean peoples of the oikoumene were located in the upper right hand section, and other peoples were presumed to be found in the other three zones: sunoikoi and antoikoi in the Eastern Hemisphere; perioikoi and antipodes in the Western Hemisphere (see Fig. 1). This model of the earth can be conceived as parallel with the astronomical sphere, its divisions being constituted by the equator and any convenient meridian and its hemispheres being symmetrical in any direction, as was explained by Geminos about A.D. 50.7 It became common in literature of the Roman Empire: a public oration addressed to Constantius Chlorus in A.D. 297 by an Autun schoolmaster compared his majesty to that of the entire four- part universe, comprehending the orbis quadrifariam duplici discretus oceano. Julius Honorius relied upon this figure in the fifth century to describe both heavens and

3London, British Museum, Department of Western Asiatic Antiquities no. 92687; a good photograph of this may be seen in Leo S. Bagrow, History of Cartography (1944, 1951; revised ed. R. A. Skelton, Cambridge, Mass.: Harvard University Press, 1964), Plt. VI. The cosmogonic interpretation was proposed by Eckhard Unger, "From the Cosmos Picture to the World Map," Imago Mundi, 1937, 2:1-7, with a photograph and illustrative drawings. Actually the text written above this design is less grandiose and merely names exploits by Sargon of Akkad; perhaps it illustrates scenes of his campaigns.

4Dicks, Early Greek Astronomy, pp. 39-42 on the need to discriminate primary evidence from later reports about the pre-Socratics.

51bid., pp. 49-55, 72-73. 6Geographia, I 2. 24. 7Fig. 1 is based upon the study by H. J. Mette, Sphairopodia: Untersuchungen zur Kosmologie des

Krates von Pergamon (Munich: Beck, 1936), esp. pp. 66-78; it is here adapted from Wanda Wolska, La topographie chretienne de Cosmas Indicopleustes (Paris: Presses Universitaires de France, 1962), p. 258. See also Geminos, Phaenomena XVI 1-2, ed. Germaine Aujac (Paris: Collection Bude, 1975); Aujac, "L'image du globe terrestre," pp. 205-208; Otto Neugebauer, A History of Ancient Mathematical Astronomy (Berlin: Springer-Verlag, 1975), pp. 578-587.

270 WESLEY M. STEVENS

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earth, and it continued to be used until about A.D. 900 as a simplified teaching diagram.8

The second model of the earth displays either two or four lines dividing the globe into three or five zones: temperate both north and south of the torrid zone, with arctic and antarctic at the extremes (see Fig. 2). Euro-Asia and the coastal lands of mare nostrum fall in the northern temperate zone, and it was assumed that the southern temperate zone was also habitable. But the literature includes debate about whether there really are inhabitants there and in the terrible climate of perusta in this model. Any such depiction of the earth also has astronomical connotations, for its two central lines are often labelled aestivus for the northerly and hiems for the southerly divisions (see Fig. 3), representing the sun's highest point on the meridian at summer solstice and its lowest at winter solstice respectively. The concept was used with reference to the heavens by all astronomers after Eudoxos (ca. 370 B.C.), at first according to the latitude of Cos and Cnidos but then attributed or adjusted to Rhodes under the influence of that great school. Those who assumed this model in reference to the earth made a variety of attempts to identify parallels of klima or latitude by using patterns of shadows cast by the sun, longest hours of daylight, and sexagesimal parts of the circumference.9 This Eudoxian concept was also applied to the earth by Krates of Mallos and apparently by Ptolemy, whence it came to be disseminated among Latin readers through the work of Macrobius and others. Its earliest manuscript dates from the late eighth century.10

8Arpad Szabo, "Roma quadrata," Rheinisches Museum, 1938, 87:160-169, discussed many references to this figure in Latin literature and established the meaning of the term quadratus as four-part (not four- cornered as in the modern rectangular concept), with equal parts meeting in the center where angles or corners occur within the circumference of the figure; he noticed also the common references to hemispheres of the orbis quadratus divided by the meridian. Lingering doubts about these matters were laid to rest by his further article, "Roma Quadrata," in Maia, 1956:243-274. I gratefully acknowledge the very full bibliography supplied by Dr. Jocelyn Penny Small, Director of the U.S. Center of Documentation, Lexicon Iconographicum Mythologiae Classicae, Rutgers University. For Autun see XII Panegyrici Latini, No. 4, ed. Edouard Galletier, Vol. I (Paris: Collection Bude, 1949), pp. 84-85; and Eumenius's appeal (No. 5, pp. 137-138) only a year later for reconstruction of the city's entry walls which had been mostly destroyed in A.D. 269; he visualized great maps with many details depicted. Surviving excerpts from Julius Honorius were edited by A. Riese, Geographi latini minores (Heilbronn: Henninger, 1878), pp. 24-55. See further MS Bern, Burgerbibliothek 45 (ca. A.D. 900) fol. 41, where the orbis quadratus occurs along with other figures of the earth in the margin of Lucan's Pharsalia.


The resemblance of this spherical figure, especially when oriented to the north, to images of the globe now current might suggest that it would encourage increasingly accurate depictions of the earth; but the narrow space of the northern temperate zone provides little scope for anyone wanting to develop a landchart. Characteristic of such limitations is the full-page representation of the globe as a zonal rota on folio 29 of MS London British Library Cotton Tiberius B.V.; there is space for only the barest sketch of lands in Asia maior et minor and only the northern shore of Africa which gives way to the equinoctial zone, an area which in this case is filled with a text concerning the circumference of the globe.

These difficulties are avoided by a third figure of the earth, the rota terrarum or orbis terrae depicting three great continents: Asia, Libya, Europa (see Fig. 4). These terms appear in this sense as early as Aeschylus (525-456 B.c.), and the figure was easily adapted to common use in early periploi, which listed the names of ports, rivers, regions, and peoples around the coasts of the Mediterranean, and often those at a very great distance from the coastline. Such lists were not necessarily pictorial; by the early second century however, the Greek Dionysius Periegetes had adapted his periplous to a model earth with three continents. 1I1 Many Latin literary descriptions, such as those of Pliny, Augustine, and Oro- sius, followed the same pattern and assumed or described this third figure of the earth. It may have been used by Sallust to depict Roman campaigns in the province of Africa-a small area which could be expanded on the rota to take up most of the space allowed for the whole continent of Libya.

asia

europa af rica

Figure 4. The tripartite model of the earth emphasizing the three known continents.

(Under Latin influences Libya eventually yielded to Africa as name for the southern continent.) This figure appears to have been used as well by Lucan to describe and depict events in Hispania or in Thessalia-also cartographically expanding in the space of the continent Europa. For these purposes the north-south rivers which

divide continents were adjusted to form variant diagrams, now called the Sallust-type or the Lucan-type; unfortunately these special variants occur only late in the tradition. Although Sallust and Lucan must have written about 40 B.C. and A.D., 60-64, the diagrams named after them do not survive in manuscripts earlier than the late

9D. R. Dicks, The Geographical Fragments of Hipparchus (London: Athlone, 1960), pp. 24-25; Dicks, Early Greek Astronomy, pp. 17-21; Aujac, "L'image du globe terrestre," pp. 196-205; Neugebauer, Ancient Mathematical Astronomy, pp. 725-748.

10Attribution to Krates is found in Ptolemy's Geographia VI 6, but it is not certain that this portion derives from Ptolemy himself. See further Destombes, Mappemondes, pp. 17, 22, and 30: type C, of which a 13th-century example is shown in Plt. IV; but the earliest extant representation is MS St. Gallen Stiftsbibliothek 237 (1st half of the 11th century), apparently adapted from a Sallust-type rota (discussed below).

"On Aeschylus see Eric H. Warmington, The Greek Geographers (London: E. P. Dutton, 1934), p. xxvii; the continents are named in texts of tragedies and fragments. On Dionysius see Henry F. Tozer, History of Ancient Geography (Cambridge University Press, 1935), pp. 281-287, who summarized the contents; he argued that it could not have been written earlier than Vespasian or later than the end of the 2nd century. G. Leue, ("Zeit und Heimath des periegeten Dionysius," Philologus, 1884, 42:175-178), however, had already discovered two acrostics in Dionysius' verses which allowed him to affirm that he was a grammaticus in Alexandria at the time of Hadrian (A.D. 117-138). His "complete guide" (to the earth) was drawn upon for Latin works by Avienus (2nd half of the 4th century) and Priscian (ca. A.D. 500); he and Ptolemy were the Greek sources for tales about monsters in the Indian Ocean who can swallow whole ships.


ninth and early tenth centuries.12 Some applications of this diagram were even more extensively cartographical. Regions were carefully blocked out around the Mediter- ranean shoreline in MS Albi 29 (late 8th century); islands of the Mediterranean could all be displayed in MS Vaticanus Latinus 6018 (8th or 9th century), as well as islands of the oceans-the Azores, the Canaries, Ceylon, and many others of great distance-projected with angular extension and foreshortened depth implying curvature of the globe. 13

Authors and artists also represented both earth and heavens with similar diagrams, each adapted according to need for generality or representative detail. As a geometri-

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O SPHAERA Figure 5. Diagrams of geometrical solids; the sphere is represented by a circle.

cal figure also the sphere is represented by a circle, as Cassiodorus explained when presenting the notion of solid numbers (see Fig. 5). It can further be compared to the circle upon which Jahweh sits in the early manuscript illuminations for the text, "It is he that sits upon the circle of the earth . . ." (Isaiah 40:22). Elsewhere Jahweh always stands, and the teaching Christ always sits upon curvature, for no other aspect of the earth is depicted by the circle.14 As a teaching device the spherical rota was simply divided by single lines to represent the waters which separated continents: the horizontal line corresponds- with the Tanais (Don) river-Black Sea-Bosphorus on the north side, and on the south with the Nile or sometimes the Red Sea, while the Mediterranean is shown by dropping a perpendicular from the center. Such an image was well known on public monu- ments, coins, and literary descriptions,15 but no manuscript diagram survives prior to Isidore of Seville, whose rota antedates the cartographical examples by more than a century.

Isidore is better known for his Origines vel Etymologiae, which supplied general information and interpretations of many aspects of life which would assist the Christian preacher or reader of sacred scriptures, including a periplus similar to that of Orosius. Late manuscripts of that book attracted to their margins the tripartite rota terrarum and other diagrams. Isidore's earlier work De natura rerum was however quite different in purpose and content: it was a schoolbook. The teaching was elementary, but within the context of seventh-century Visigothic Spain it served as a useful introduction to the fields of study; the rota first appeared in this earlier work and is extant in the earliest manuscript.

In his excellent edition of De natura rerum Jacques Fontaine has identified three manuscript traditions.16 The first contained the forty-six chapters which Isidore sent in 612 to his protege Sisebuto, the young king of the Visigoths. Not only was Sisebuto literate and able to answer Isidore in verse, but his letter of reply included an explanation and diagram of a solar eclipse-demonstrating how the elementary textbook could become a stepping stone to more sophisticated knowledge.17 This

l2See the list of manuscripts in Destombes, Mappemondes, pp. 37-39. 13 Facsimiles were published in Itineraria et alia geografica, ed. Fr. Glorie, Corpus Christianorum, Series

Latina, Vol. CLXXV (Turnhout, Belgium: Brepols, 1965), p. 470; and Destombes, Mappemondes, Plt. XIX.

14Cf. also Job 22:14 and Prov. 8:27, in which the same Hebrew word can be rendered circuit, arc, compass, or orb. It seems unlikely that any of the three Biblical authors intended thereby a two- dimensional description of limited space, but rather a figure of enormous range. It is in this latter sense that Greek and Latin commentators and translators took the term, before the Enlightenment's inappropri- ate demands upon the language.

15Destombes, Mappemondes, pp. 3-4. 16Jacques Fontaine, ed., Isidore de Seville: Traite de la nature (Bordeaux: Feret et Fils, 1960), pp. 38-45,

75-82.


version of the work with the verse letter is called the short recension, and it is found in the earliest extant manuscript, El Escorial R.II. 18, folios 9-24, written in a single Visigothic hand within the period 636-690. To this Isidore added in 613 a forty- seventh chapter, "De partibus terrae," followed by the rota under discussion; this chapter was copied into the El Escorial manuscript on folio 24v in a somewhat different Visigothic uncial script, also within the seventh century, and supplies evidence for Fontaine's putative middle recension. A third version with forty-eight chapters was developed later by other persons and is known through manuscripts from England, Fulda, the region of Murbach, and Verona; it too includes the final chapter "De partibus terrae" with its rota terrarum in all completed manuscripts. Fontaine included seven other teaching diagrams from Isidore's short version of 612, but unfortunately he and all other editors published the 613 text of the final chapter "De partibus terrae," lacking its rota terrarum. Yet no completed second or third version manuscript exists without it.18

The reasons for this omission are not clear. The tripartite or Isidorean rota appears to be so simple as to require no discussion. Like the Babylonian clay imago, however, it could possibly represent the earth as a disk, and some writers have presumed that it does so-especially in the hands of Isidore. There are several passages from his works which have been construed in accord with that assumption: De natura rerum X, XII, XVI, and Origines III and IX. If such allegations were true, Isidore would stand as a remarkable exception to the Hellenistic tradition, surviving in both Greek and Latin descriptive literature, which almost uniformly discussed the earth as a globe and the heavens as a sphere.19 But those passages have been misconstrued. For example Isidore was rebutting a local superstition when he affirmed in De natura rerum XVI "De quantitate solis et lunae," that everyone experiences the sun and moon, their sizes, their distances, and their radiation in exactly the same way no matter where they may be on the face of the earth- "Similis sol est et Indis et Brittanis"-and this includes even that unusual enlarged appearance at the moment of rising-eodem momento in the East exactly as in the West. But Isidore does not assert that the sun itself is seen to rise simultaneously at eastern and western extremities of the globe- an assertion which would allow an historian to suspect that flatness of the earth's surface was implied, but which would also contradict Isidore's discussions of time- reckoning.20 Isidore also explains the five climates of earth in parallel with the five bands of the celestial sphere in De natura rerum X and XII, as on the model of our Figures 3 and 4. Chapter X, "De quinque circuli mundi," is plainly based upon the Hellenistic model of a spherical universe (= kosmos = mundus), but it too can be misinterpreted. This is because the language is not at all clear: like Chapters XI and XII it emphasizes the interrelation of all parts of the universe rather than describes the ones in which we are interested; and one of the drawings rearranges the five great

17Ibid., pp. 329-335 and 151-161. 18Manuscripts and editions are described in ibid., pp. 19-38 and 141-145. 19The only exception that I know is in late Greek literary polemics: a Syrian merchant (or monk) of the

6th century apparently named Cosmas. As a Nestorian Christian and a Biblical fundamentalist, he distorted texts in order to portray the universe as a doubled tent or tabernacle and to ridicule the dominant Christian orthodoxy of such teachers as John Philoponus. See Wolska, La topographie chretienne, and Marshall Clagett, Greek Science in Antiquity (1955; 2nd ed., New York: Collier Books, 1963), pp. 169, 175-176, 179, 207-217. Cosmas' notion cannot be attributed to Christians in any common or general sense of the term, even in the time or region in which he lived.

20De natura rerum XVI is summarized less clearly in Origines III, 47, "De magnitudine solis," but neither version can justify the claims that "Isidore thought the world was flat" or that "he tended to view the earth in the shape of a wheel or flat disk," a tendency also inferred from his doubts that Antipodae lived opposite us. See most recently the otherwise commendable article by T. R. Eckenrode, "Venerable Bede as a scientist," American Benedictine Review, 1971, 21:486-507. Eckenrode is certainly correct in affirming that "the scholarly Bede knew more about this universe than the scholarly Isidore of the previous century" (p. 489).


zones (circuli) as petals of a flower! However disconcerting it may be as a teaching diagram, that device displays both the northern and the southern temperate zones of the earth as habitable, a touchstone which most modern commentators use as evidence for a concept of sphericity (e.g., Bunbury, Dreyer, Wright, Bagrow).

Again, Isidore joins those among Greek and Latin scholars who doubted that Antipodae live opposite them (Origines IX 2, "De gentium vocabulis," 133; and XIV 5, "De Libya," 17). Antichthones or antipodes were people and not poles, as is sometimes assumed in modern discussions of these questions. Their place on the earth was to be opposite the mapmakers, whether Greeks or Latins or Visigoths, not opposite a projected pole. It is worth repeating that there never was a doctrine of the Christian Church condemning the idea that there might be inhabitants of the southern temperate zone or of a presumed fourth continent.21 But rejection of such speculations as poetic fancies without supporting evidence bears no consequence for concepts of the earth's shape.

On the other hand in Origines XIV 2, "De orbe," Isidore describes the shape of the earth directly: "Orbis a rotunditate circuli dictus, quia sicut rota est; unde brevis etiam rotella orbiculus appellatur." Modern readers trying to span the ages might assume that the three terms here juxtaposed-orbis, rotunditas, circulus-only refer to a two-dimensional circularity; however the concept of sphericity is not merely implied but is taught overtly in this language. The Epistula Sisebuti 38-41 confirms this fact in the plainest way. In order to avoid redundancy in his verses Isidore's student applies the term globus to the earth, a globus which intervenes with the sun's rays to cast a shadow upon the moon. We thus have no alternative but to agree with Charles W. Jones that "[Isidore's] cosmology, insofar as it has any consistency, is only consistent with a globular earth."22 "Sicut rota est" then refers to a circular diagram of the globus terrae.

II

In the manuscript examples of rota terrarum a reverse image sometimes accompanies texts of Sallust, Lucan, and other Latin authors; one is also found in a fourth version of Isidore's schoolbook not previously noticed. Six English manuscripts of De natura rerum with the final chapter and rota survive, forming an Isidorian tradition which varies significantly from the long version discussed above: the text is altered in many chapters, and the design of the final rota is quite different (see Fig. 6). These changes indicate that Isidore's book was actively used in early Saxon and perhaps Celtic schools. But why is the rota terrarum in mirror image in some of these manuscripts? Indeed, this reversal goes against schemata in earlier exemplars of De natura rerum

21In Speculum, 1976, 51:752-755, I have discussed medieval evidence and modern assumptions about antipodes in a review of K. Hillkowitz, Zur Kosmographie des Aethicus, Vols. I (Cologne, 1934) and II (Frankfurt am Main, 1973), and other related literature.

Among those who ridiculed the idea that the cosmos was spherical, the argument therefrom that the earth too was a globe, and the claim that therefore on the part opposite them there must be animals and men (Antipodae) upside down were Plutarch (fi. ca. A.D. 90-125), De facie in orbe lunae VII, and the heterodox Christian and rhetorician Lactantius (fi. A.D. 284-317), Divinae institutiones III 24. Neither offered any positive description of the shape of the earth, but merely scoffed at absurdities and contradic- tions of the philosophi. Lactantius became important in the fifteenth century both because Lorenzo da Valla praised the Ciceronean quality of his style and later because Copernicus cited him in the dedicatory letter for De revolutionibus: "For it is known that Lactantius-a poor mathematician though in other respects a worthy author-writes very childishly about the shape of the earth when he scoffs at those who affirm it to be a globe." This was repeated by Galileo in his Letter to the Grand Duchess Christina, which I quote from the translation by Stillman Drake, Discoveries and Opinions of Galileo (New York: Double- day, 1957), p. 180. My appreciation for the reference to Copernicus and Galileo goes to Professor Bert Hansen, Institute for History and Philosophy of Science, University of Toronto.

22Charles W. Jones, Bedae Opera de temporibus (Cambridge, Mass.: The Mediaeval Academy of America, 1943), p. 367, and his article "The Flat Earth" cited in note I above.


// ~~In al \\ // sunt prouinciae... \

i\,n af rica in e urop

Figure 6. The reversed tripartite rota from the Exeter and Vitellius manuscripts of Isidore's De natura rerum.

(see Fig. 4). The earliest English manuscripts are Exeter Cathedral 3507, British Library Cotton Domitian I (both second half of the 10th century), and British Library Vitellius A. XII (end of the 11th century).23 Their texts have been collated and are nearly identical; but there are variant readings which make it clear that they must have been copied directly from a single exemplar, not from each other. Yet despite the identity of their modified long version texts, Domitian gives a simple Isidorean rota (Fig. 4) whereas Exeter and Vitellius give the reverse image- apparently by choice rather than by error. How can this be explained in a scholarly text?24

Hellenistic tradition represented astronomical phenomena in alternate ways that may lead us to understand the manner in which the rota terrarum was conceived and used. There have always been two perspectives on the globus caelestis and its stellar phenomena, which result in two quite different projections of star charts and land charts. If the astronomer looks up at the sky with Asia and its oceanus orientalis at his head, then europa est dextera, africa est laeva. On the other hand if he imagines himself outside the globe and looking east, he would see that europa est laeva, africa est dextera.

Both perspectives are found in popular literature. Latin texts of the several versions of Hyginus and Aratus have illustrations of constellations (such as Perseus or Eridanus) which face the viewer or which turn away from and are laterally reversed for him. In the one case the viewer is thought to be within the globe or

23For the present discussion only these three-the Exeter, Domitian, and Vitellius MSS-will be cited. All six will be analyzed elsewhere.

24Historians of geography have sometimes made the peculiar assumption that many unexpected notions during the Middle Ages can be attributed to ignorance or error and need no explanation; for example Destombes, Mappemondes, p. 37, commented in 1964 on the reversed rota terrarum in some Sallust MSS: "Ces mappemondes sont toutes du type A, la plupart du type A3 avec les noms des trois continents quelquefois interchanges par suite d'une erreur ancienne." Without being aware of any pattern, Gerald R. Crone studied The Hereford World Map (London: Royal Geographical Society, 1949), p. 6, and reported that "the draughtsman has carelessly interchanged the names of Africa and Europa." At the cathedral bookshop unsuspecting tourists are offered a replica on which the modern draughtsman has "corrected" the past.


sphere of stars looking out at the figures; in the other he is assumed to be looking on from the outside.25 The more sophisticated planispheres of astronomers oriented to the north celestial pole could also take either perspective: the early ninth-century Fulda planisphere viewed the skies from without, as had Hipparchus. The equally venerable Salzburg planisphere assumed the perspective of a viewer within the globe looking out, in effect similar to Ptolemy's viewpoint from the south celestial pole.26

Orientations for the earth were similarly flexible. When geographers prepared picturae of their sphaerae terrestris, they often placed Asia and its oceanus orientalis at the head of a chart or at the top of a codex leaf, and regions were projected onto the flat surface according to the relationships of the planisphere. But there were alternatives: one could face in any direction while placing each zone or continent in true relationship with the others to the left or right, upper or lower. For example, Aristotle explained in De caelo II 2 that the Greeks are to be found on the right of the diagram in the lower hemisphere; the North is lower, and those living in the South are in the upper hemisphere on the left. So far as he was concerned, therefore, the Pythagoreans had everything backwards, and he rejected their apparent practice of depicting Europa in the upper part of the sphere. Both may have been assuming the four-part zonal concept (Fig. 2) with meridian dividing hemispheres, several centuries before Krates. Apparently the Pythagoreans depicted the globe so that the stars appeared to move from left to right, whereas Aristotle insists on the viewer facing the heavens and imagining himself turning right (forward) to left with the stars.

Later Hipparchus was critical of Eratosthenes' mirror-image astronomy as well. From the outer Hipparchan perspective on the celestial sphere projected onto the globe of the earth, Europa and its oceanus septentrionalis would be found on the left, as with the Isidorean rota; but from the inner Ptolemaic perspective27 Europa would then be on the right, as with the reversed rota. The cartographer who knew a globus caelestis or a stellar planisphere of the first type (looking down on it all) could apply his terms for the oceans of stars equally well to the geography beneath them without turning his head, whereas the cartographer who knew a globus caelestis or a stellar planisphere of the second type had to look up to the stars and then down to the lands, thus requiring him to distinguish between celestial and terrestrial regions and to keep in mind the distinct perspectives required.

Thus we may recognize two conventions for representing the heavens, each of which had intelligible consequences for the rota terrarum: neither the Isidorean

25Many of these storybook illustrations may be seen in Fritz Saxl, ed., Verzeichnis astrologischer und mythologischer illustrierter Handschriften des lateinischen Mittelalters, Vols. I and II (Sitzungsberichte der Heidelberger Akademie der Wissenschaften, Philosophische-Historische Klasse, Vols. VI, 1915, Nos. 6-7, and XVI, 1925-1926, No. 2); Fritz Saxl, H. Meier, and H. Bober, eds., Handschriften in englischen Bibliotheken (London: Warburg Institute, 1953); and Patrick McGurk, Catalogue of Astrological and Mythological Illuminated Manuscripts in Italian Libraries other than Rome (London: Warburg Institute, 1966). McGurk appears to be the first to notice a pattern of perspectives.

26The Fulda planisphere is MS Basel Univ.-Bibliothek A.N. IV. 18 (Fulda, early 9th century), fol. lv. The Salzburg planisphere is CLM 210, fol. 113v (810-818?), known in Regensburg during the ninth century. Further planispheres which take each perspective have been listed by Patrick McGurk, "Germa- nici Caesaris Aratea cum scholiis, a New Illustrated Witness from Wales," The National Library of Wales Journal, 1973, 18:197-216, especially pp. 200-201.

27 As above, I refer to Hipparchus and Ptolemy only with respect to viewpoints in observing the heavens. It is worth recalling that the so-called "Maps of Ptolemy," so often cited by historians of Renaissance or Enlightenment science, were drawn probably in the 14th century on the basis of a Byzantine "Geographia" composed in the 10th or 11th century. See Lev. S. Bagrov [Leo S. Bagrow], "The Origin of Ptolemy's Geographia," Geografiska Annaler, 1945, 318-387, especially pp. 368-372 and 387; Bagrow, History of Cartography, pp. 34-37; and Otto Neugebauer, The Exact Sciences in Antiquity, 2nd ed. (Providence, R.I.: Brown University Press, 1957), p. 227; Neugebauer, Ancient Mathematical Astronomy, pp. 885-886. A rebuttal of Bagrow was undertaken by Erich Polaschek, "Ptolemy's Geographia in a New Light," Imago Mundi, 1959, 14:17-37; but recent studies by David Thomason at the Warburg Institute indicate that the "Maps of Ptolemy" probably were composed in the 14th century.


image nor the reverse image of the globe indicates a lack of understanding, a failure of observation, or a repetition of error. Both may be best understood in terms of a priority of the spherical cosmos in the picturae of literati, cosmographers and cartographers. The results of this enquiry may be summarized thus: In the tradition of Hellenistic science there were several diagrams for presenting the shape and features of the earth's globe. All continued to be cited in Roman a-nd medieval literature, and all show the earth to be spherical. But by far the earliest of these diagrams extant in dated manuscripts is the rota terrarum with three continents. It properly belongs together with the final chapter which Isidore of Seville added in 613 to his own work De natura rerum. A copy of the long version was then used, adapted, and elaborated in schools of eighth- and ninth-century England, whence it passed also to Fulda, Verona, and elsewhere. Among the teachers in England were scholars who knew some astronomy and thought of heavens and earth as two spheres-from which the rota model first derived. One of them saw his rota as oriented to an inner or Ptolemaic perspective on the heavens; thus looking up, he found continents of earth beneath continents of stars. Turning to his work table, he maintained those relationships. Although he did not intend to confuse modern readers, the resultant figure became a riddle for generations of moderns. They have labeled as error what in fact was astronomy.

Documents

STEVENS Wesley M - The Figure of the Earth in Isidores de Natura Rerum