Chapter VI: Cosmogony, Cosmology, and Cosmography

In the preceding chapters the attempt has been made to show the origins of a large part of the geographical lore of the Crusading epoch, the sources from which we may learn about it, and where it stood in the classification of learning. Now we may turn to our central theme: an estimate of its actual substance and character.

This geographical lore was in no sense a unified body of knowledge and belief. It was no more a unit than the religious thought of the age, or the philosophy, astronomy, or morals. No one in the Middle Ages was acquainted with all the facts and theories with which we shall have to deal. Mental caliber, credulity, critical spirit, curiosity, opportunities for research and for travel—these all varied widely with the individual and determined his geographical concepts. Nevertheless, though there was no unity of knowledge or belief in regard to specific facts and no unity of point of view, the reader will not fail to perceive, in the multitude of illustrative details which are presented, that certain habits of thought and modes of expression were typical of the epoch as a whole.

We must first discuss what was known and believed about the earth in its larger relations, both in time and space, to the remainder of the universe: opinions about the Creation, about the size and shape of our terrestrial globe, about the influences exerted by the heavenly bodies in determining or affecting geographical conditions upon its surface.

In the Introduction we explained why it is justifiable when dealing with ancient and medieval geography to wander into the fields of cosmogony and cosmography far beyond what are now regarded as the rightful limits of geography. The present chapter, it is hoped, will make clear how closely medieval conceptions of the present condition of the earth may be connected with the medieval idea of the origins and nature of the universe.

_GENERAL CHARACTER OF THE COSMOLOGY AND NATURAL SCIENCE OF THE PERIOD_

These difficult questions of cosmogony, cosmology, and cosmography excited keen and vivid thinking because they lie on the border between philosophy and theology. Men were more interested in attempting to solve the insoluble mysteries of God and the universe than they were in the world of nature immediately surrounding them. Immense and weighty volumes were written in commentary on the Works of the Six Days, wherein complicated arguments were elaborated with the finesse of scholastic logic. In an age of faith, the religious enthusiasm of the architect and artisan was transmuted into lofty cathedrals; that of the theologian turned to the elucidation of the words of Scripture. To analyze these words, to comment upon their minutest detail, to reveal the meaning that presumably lay behind them was not only a work of piety and devotion but an absorbing intellectual pastime for keen-witted thinkers. In more concrete realms of natural science, the epoch was characterized by little enough observation and creative thought. The teachings of Plato, of Aristotle, and of the other available classical, Arabic, and early Christian authorities were accepted and adopted uncritically. Very different was the case with matters of cosmogony and cosmography. Here was highly controversial ground where classical opinions were either enthusiastically defended as casting light on Scripture or else bitterly attacked as subversive of all truth.

THE CHARTRES GROUP: BERNARD SYLVESTER AND THEODORIC

We have seen in Chapter IV that the scholars of the Chartres group and their pupils during the early twelfth century were endowed with peculiar freedom of thought.[565] We note in the works of Bernard, Theodoric, Adelard of Bath, William of Conches, and Bernard Sylvester a wide departure from authoritative, orthodox theology. Theodoric, William, and the two Bernards were readers of Chalcidius’ translation of the _Timaeus_, of Macrobius, and perhaps of the writings of the great ninth-century Platonist, John Scot Erigena, and all four felt the powerful and seductive attraction of Platonism. Bernard Sylvester was almost an out-and-out pagan, so much so, indeed, that his writings can hardly be considered to lie within the pale of Christian theology.[566] Theodoric and William tried harder to reconcile Platonism with the teachings of the church, yet they did so in a rationalistic spirit almost as abhorrent to strict orthodoxy as the paganism of Bernard Sylvester. Theodoric expressly stated in his _De sex dierum operibus_ that he was going to explain the different Works of the Six Days “according to physical principles,” and, following the letter of the text,[567] he proposed to avoid all allegorical and moral interpretations of Scripture. He believed that the best way to attain a genuine knowledge of God was through an accurate understanding of what God had created; and his explanation of the Creation, as we shall soon see, was independent to a degree that amazes us in a writer of his time. The following phrase is particularly significant where Theodoric extols Moses’ treatment of the Creation in Genesis, saying: “He shows in a rational manner the causes out of which this world has come into existence and the order of time in which this same world was founded and adorned.”[568] Hauréau writes of the first book of Theodoric’s commentary: “Quant au premier livre, essai d’accord entre la Genèse et le _Timée_, où l’on voit la religion et la philosophie conspirant à résoudre le plus grave et le plus obscur des problèmes, le problème de l’être, et se déclarant satisfaites de l’avoir résolu, ce premier livre est ... de plus grand intéret.”[569]

ADELARD OF BATH AND WILLIAM OF CONCHES

In the _Quaestiones naturales_ Adelard of Bath gives vent to his scorn for the mentality that blindly accepts beliefs merely because they have the weight of authority behind them. In an extraordinary passage he expresses these ideas thus (as translated and paraphrased by Professor Haskins[570]): “‘It is hard to discuss with you,’ Adelard tells his nephew [in the dialogue form of the _Quaestiones naturales_], ‘for I have learned one thing from the Arabs under the guidance of reason; you follow another halter, caught by the appearance of authority, for what is authority but a halter?’... ‘If reason is not to be the universal judge, it is given to each to no purpose.’[571]... While plants spring from the earth by God’s will, this does not act without a reason.[572] Human science must first be listened to ... and ‘only when it fails utterly should there be recourse to God’ as an explanation.”[573]

William of Conches shows the same spirit where he insists that God acts reasonably and not capriciously. He writes: “I am aware that some people assert, ‘Though we do not know how this happens to be so, we know that God can make it so.’ Wretched ones! What is more craven than to talk in that way! Because God can do something is no sign that he actually does it, nor any reason why he should do it, nor any reason why it is useful that it should be done. For God does not do whatever he can do. To employ a rustic expression: ‘God can make a calf out of a tree trunk,’ but does he ever do so?”[574] William apparently, unlike Theodoric, thought that we are justified in avoiding irrational deductions from Scripture by an appeal either to an allegorical interpretation or—what is even more surprising at a time when the word of authority was usually regarded as all-sufficient—to one’s own intellect: “We may begin our reasoning from the authority of a master, but it should be perfected by our own intellect.”[575]

CONCEPT OF NATURAL LAWS

Thus we see in the writings of Adelard, Theodoric, and William that the approach was tentatively made toward the acceptance of the doctrine that the universe is governed by natural laws. This doctrine, upon which the edifice of modern science has been built, was also given partial expression by other thinkers of the twelfth century. John of Salisbury stated in effect that a sequence of causes gives rise to all things that we may perceive with our senses, that we call these causes nature, that nothing happens that is not the result of natural causation even though the operation of this causation may be concealed from us; finally, that the first cause of all is the will of God.[576] Alan of Lille clothed a similar theory in allegory by personifying Nature in poetic form as the representative of God and making her say: “Hear how in this universe, as in a great city, order is established by the control of a majestic government” (Moffat’s translation).[577] Much the same opinion was expressed by an anonymous Scandinavian historian of the early thirteenth century in his Latin _Historia Norwegiae_. After describing a terrible volcanic upheaval from the bottom of the sea,[578] this writer adds that many people regard such occurrences as prodigies, believing that the world itself thereby gives warning of its own destruction.[579] Citing Solinus, he goes on to set forth a purely physical explanation of earthquakes and volcanic eruptions and adds that, though it may not be possible to attain to clearsighted understanding of these phenomena and of the major marvels of the world, they should not be looked upon as prodigies nor considered as portents of universal cataclysm. On the contrary they are, as it were, the servants of the all-knowing and immutable founder of the universe to whose nature through some marvelous process they have been placed in bondage.[580]

THE ORTHODOX TENDENCY

This sort of reasoning, however, was exceptional. In the mid-twelfth century the appearance of Peter Lombard’s _Sententiae_ tended to divert the theologian’s mind from Platonic and rationalistic studies and to restore Church Fathers and Scripture to paramount authority.[581] We look in vain for traces of the liberal attitude of the Chartres scholars in the orthodox works of such prolific writers but perhaps less clear thinkers as Peter Comestor, Giraldus Cambrensis, Gervase of Tilbury or even Alexander Neckam. Giraldus’ _Symbolum electorum_[582] contains a cosmography in verse which explains the Scriptural view of the Works of the Six Days, and though we feel in this poem the influence of the Peripatetic physics—which by this time were becoming universally known—no attempt was made to expound the work of the Creation according to physical laws. In the _Topographia Hiberniae_[583] Giraldus illustrates his own attitude and the dominant attitude of his age by the moral he draws from the story of eagles which occasionally fly so high that they scorch their wings in the sun. This he compared to the hopeless vanity of the man who tries to solve by reason or by knowledge God’s riddles of the Creation and of the universe. Neckam also despairs of explaining the mysteries of nature and asks, “Who may comprehend the causes of things?” He describes thunder and lightning briefly but adds, “The herald of the thunder fills the mind with terror and shows how great is the creator thereof.”[584] Even Michael Scot, who enjoyed the patronage of the enlightened, scientifically minded Emperor Frederick II, attributed the fact that the waters of the spherical earth are held in place to “a secret virtue ... beyond human ken and merit” (Haskins).[585] Gervase of Tilbury reproduces uncritically in his _Otia imperialia_[586] the ideas compiled by Peter Comestor regarding the Creation. These were strictly correct opinions on which no suspicion of heterodoxy could be thrown. Comestor went out of his way to express opposition and antagonism to Platonic teachings.

EFFECTS OF INFLUX OF ARABIC SCIENCE

The conventional orthodox position, however, did not remain unchallenged. The influx of Moslem Aristotelian lore at the end of the twelfth century was held to be as menacing to the integrity of the ecclesiastical tradition as any of the Platonic doctrines. But, though stern prohibitions were leveled against the study of Aristotle and his Arabic interpreters, the seductions of Aristotelianism could not be resisted, and those elements of Peripatetic science which did not seem utterly outrageous to Christian theology became the accepted and authoritative science of the West in the mid-thirteenth century. William of Auvergne, bishop of Paris, stood out valiantly against what he regarded as teachings subversive of Christianity and of morals and in his vigorous opposition to Aristotelianism even went so far as to adopt many of the Platonic doctrines that had been popular among the scholars of Chartres during the preceding century.[587] But translators like Gerard of Cremona had done their work too well, and the enormous tomes of Albertus Magnus were based to a large extent on the learning of the Stagirite.

_THE CREATION_

The usual medieval treatise on the Works of the Six Days as described in the Book of Genesis deals with many problems. Some of these are abstruse and metaphysical: questions of the nature of God and the nature of time and space. With these we are not concerned. Others are more concrete: questions of the materials out of which God made the universe and of the actual manner in which he worked.

PROBLEMS

For the sake of clearness let us state some of these questions as follows, (1) The question of whether matter existed prior to God’s creation of the world. That is to say, Did God fashion the universe out of a pre-existing substance or did he make it out of nothing? (2) The question of the manner in which the universe was fashioned after it was once “created.” (3) The question of what furnished the light during the first three days before the creation of the sun. (4) The problem of whether the Six Days were actual divisions of time or merely hypothetical divisions of the process of creation. (5) The question of the nature of the waters above the firmament. (6) Various problems arising in regard to the nature and location of Paradise and of the four rivers flowing from Paradise. The first four problems are discussed briefly in the present chapter. That of the waters above the firmament is left for Chapter VIII (on waters), and that of Paradise for Chapter XII (on regional geography).

THE PREËXISTENCE OF MATTER

(1) Did matter exist prior to God’s creation of the universe as we now know it?

Consistently with his Platonism, Bernard Sylvester thought that God formed the universe out of what he termed _materia primordialis_—a chaotic mingling of the elements that had coexisted with God before he converted the universe into its present shape.[588]

_The Orthodox View_

Theodoric of Chartres, on the other hand, explicitly denied the coëxistence of the _materia primordialis_ with God before the Creation. In this respect he showed himself far less divergent than Bernard from the Christian point of view. The work of the first day, he said, was the creation from nothing of the _materia_ of the universe, out of which earth and heaven, fire and water and life were to be evolved.[589] This _materia_ was the _hyle_, or chaos, of the ancient philosophers, he explained, and was designated by Moses in the book of Genesis under various names.[590] For example, when Moses wrote, “In the beginning God created the heaven and the earth” (Gen. i, 1) the words “heaven” and “earth” referred to chaos; when Moses wrote, “And the earth was without form and void” (Gen. i, 2) the word “earth” referred to the primordial mixture of land and water, a mingling of land that was not solid and of water that was not liquid. Air and fire at that time were of about the density of water.

Theodoric’s interpretation of the initial process of the Creation was entirely in keeping with the views of more orthodox writers. Peter Lombard, for instance, wrote as follows: “In the beginning God created the ‘heaven,’ that is to say the angels, and the ‘earth,’ by which is meant the material which composed the four elements. The latter were as yet in the confused and formless condition to which the Greeks gave the name of chaos, and this was before any day.”[591]

Peter Comestor also set forth an orthodox view of the Creation. In his commentary on Genesis he revealed a love of the number three and classified every thing possible into groups of three.[592] He pointed out how Moses had avoided three errors. “First, that of Plato, who had conceived of three coëxistent things, God, _ile_ (_hyle_, or chaos), and time, and that the world was made out of _ile_; second, that of Aristotle, who had conceived of two coëxistent things, the world and the fashioner thereof (_mundus et opifex_); and third, that of Epicurus, who had also conceived of two, space (_inane_) and matter in the form of atoms, and that in the beginning natural processes had brought together certain atoms to form water, others to form earth, and others to form fire. Moses, however, had said that God alone was eternal and that the world was created out of nothing, for there was no matter in existence prior to the ‘Creation.’”[593] “In the beginning” meant in the beginning of time as well as of matter, for time and matter were coëternal.[594]

_A Rational View_

William of Conches refused, on rational, physical grounds, to believe in the possibility of a chaos preëxisting the Creation.[595] Having accepted the classical doctrine whereby the four elements were arranged in concentric spheres in order from heaviest to lightest,[596] he was unable to conceive of a time when they could have been so intermingled that they contradicted this law, though there may have been a time, he conceded, when the earth was completely enveloped in a thick mantle of water reaching very high and when air and fire themselves were denser than they now are. Such a condition, William thought, was that described in Genesis i, 2.[597]

PROCESSES OF THE CREATION

_Theodoric of Chartres’ Theory_

(2) How was the universe converted into its present form after God had once created it?

Most commentators answered this either by saying or tacitly implying that it was through the immediate operation of God’s will alone. Theodoric of Chartres’ theory, therefore, is peculiarly interesting, because Theodoric maintained that the formation of the universe resulted from what we should now style a series of purely mechanical and chemical reactions which began, once the composition of the _materia_ was completed, on the first day. For its time this was an extremely hazardous view, akin in some respects to the modern belief in the sufficiency of physical and chemical action to produce practically all observable phenomena.

Let us examine Theodoric’s theory in a little greater detail. In Genesis i, 2, we read the words, “And the spirit of God moved upon the face of the waters.” Theodoric explained that by the “waters” was meant the whole of matter:[598] the “spirit of God” was that which was destined to give order and form to the chaos, that is to say the “force which fashioned” or “operated” (_virtus artifex_ or _virtus operatrix_). Plato had called this force the World Soul, the Christians called it the Holy Ghost,[599] and through its agency the evolution of the universe out of chaos by physical processes was rendered possible.

Coincidently with the creation of the original _materia_ the universe had assumed a rotary motion,[600] each complete rotation marking a day. In the further unrolling of the universe, fire was the active element (_artifex et efficiens causa_), earth the passive element, and air and water stood as intermediaries between fire and earth. During the first rotation, or first day, the fire heated and illumined the inferior elements in such a manner as to cause the air to be released from them (_aer ex inferioribus elementis spissatus_), and thus the atmosphere came into existence.[601] On the second day the fire, by illuminating the air, transmitted heat to the third element, water, which rose in the form of clouds. Some of this vaporized water ascended so high that it passed into the second heavenly sphere, where it became the “waters above the firmament,” the firmament itself, according to Theodoric, being the atmosphere.[602] So much water in this manner was absorbed out of the original _materia_ that inevitably on the third day the earth appeared like islands in the midst of the waters remaining behind. Theodoric compared these to islands that are formed when water dries after it has been spilled upon a table. Immediately the heat of the atmosphere was mingled with the humors of the earth, and the latter thereby received the power of producing vegetable life, herbs and trees. On the fourth day the stars were formed out of the waters which had been drawn above the firmament. On the fifth day the heat of the universe brooded over (_incubuit_) the waters of the earth’s surface and gave birth to fish and birds. Finally, on the sixth day, the life-giving heat reached the earth; and from it the animals were created, including, of course, man.[603]

_William of Conches’ Theory_

William of Conches’ theory of the Creation did not differ a great deal from that of Theodoric, except that the _materia primordialis_ was not, in his opinion, a chaotic mingling of the elements; for within it, he thought, as we have already seen,[604] that the elements were arranged in their proper order according to accepted classical laws of physics. The lands were uncovered by the removal of the waters, though this took place later in the process according to William than it did according to Theodoric. William attributed the drying off of the waters partly to the warmth of the stars (which were not formed until the fourth day) and partly to the creation of the water and land animals on the fifth and sixth days respectively.[605] In different portions of this primordial land, when it was just in the act of emerging from the waters, fiery, watery, earthy elements were present in varying quantities. This condition gave birth to divers varieties of animals. Where the fiery element was in excess, choleric animals, like the lion, came into being; where the water element prevailed, phlegmatic animals, like the pig; and the earthy element produced melancholic creatures like the ass and cow. At the one and only place where the combination was absolutely equal, man appeared. Woman, on the other hand, was made from a combination almost like that of man but one in which the colder elements were very slightly in excess, because the warmest of women by nature is colder than the coldest of men! This last, an extremely free and heretical and from our point of view unchivalrous theory, William retracted in his old age.[606]

FUNCTION OF LIGHT IN THE CREATION

(3) What was the nature of the light which God made when he said, “Let there be light”? Although Augustine had interpreted this passage allegorically or mystically as referring to the creation of the world of the angels,[607] he had also suggested that God might have created an actual body of light corresponding to the sun. Bede[608] developed the latter suggestion and maintained that there must have been a luminary revolving around the earth as does the sun. In the twelfth century Hugh of St. Victor and Peter Comestor, both of whom interpreted Scripture more or less literally in this respect, followed Bede. Hugh maintained that this original light was like a luminous cloud which rose in the east and set in the west,[609] and Comestor spoke of it in much the same terms.[610] Other theologians, however, refused to believe that such a light could have actually existed and reverted to Augustine’s first explanation that by the light was meant the world of angels as distinct from the world of evil spirits below.[611] Peter Lombard referred to both interpretations, though he appears to have been inclined to favor the more literal and materialistic theory of Bede.[612]

With Robert Grosseteste light is made to play the leading part in the entire process. In his unpublished _Hexaemeron_[613] and in the _De luce_[614] he sets forth a theory of cosmogony which was derived in part from the Moslems but in essentials was original.[615] We trust that the following brief statement of the theory does not do violence to the thought of Grosseteste as expressed in the _De luce_. He conceived of light as the first corporeal form and also as giving form to the _materia prima_ of the universe. By radiating through the unformed _materia prima_ the light converted it into a sphere. Thereupon the light made its way from the outer edge of the sphere towards the center. As it passed through the various realms of the universe it diffused, rarified, and purified the _materia_ of each, but with each stage of its advance its powers were diminished and correspondingly the potentiality of each successive realm of being purified was diminished. Thus thirteen concentric spheres were produced, nine celestial spheres and four spheres of the elements, and each of these was more complex, dense, and impure than its neighbor above.

THE NATURE OF THE SIX DAYS

(4) Were the Six Days described in the book of Genesis actual divisions of time? The words of the Bible seemed to be contradictory on this point. From the words of Genesis alone one would gather that the completion of the universe was accomplished in six days. On the other hand, we read in Ecclesiasticus (xviii, 1), “He that liveth forever created all things together” (Qui vivit in aeternum, creavit omnia simul). According to Theodoric of Chartres[616] these two statements referred to different events. The passage in Ecclesiasticus applied only to the creation of the _materia primordialis_ on the first day. The works of the succeeding days were the result of the automatic development of natural processes by which the universe became as we now know it. Belief in the reality of the duration of the Six Days was shared with Theodoric by most commentators, such as William of Conches, Hugh of St. Victor,[617] Peter Lombard, and Peter Comestor. Augustine, however, had argued in a more abstruse vein that the “days” were not actual units of time but that they represented merely so many distinct operations in the work of creation.[618] And in our period Arnold of Chartres urged that the Creation was carried out in one day and all at once (_uno die et semel_).[619]

ETERNITY OF THE UNIVERSE

Though they differed in the details of interpretation, these theories were all based on the fundamental acceptance of the axiom, deduced from Scripture, that God created the universe out of nothing. In Chapter II was explained the antagonism between this view and the Aristotelian doctrine of an eternal, periodically re-formed universe. Certainly, among Christians of our period, no one believed either in the eternity or in the periodicity of the universe, although the existence and nature of these concepts were well known. Both theories were set forth in Seneca’s _Quaestiones naturales_,[620] in translations of Plato’s _Timaeus_[621] and of Aristotle’s _Meteorology_[622] and _De generatione et corruptione_,[623] and in translations from the Arabic such as the _Liber introductorius in astrologiam_ of Abū Maʿshar[624] and the pseudo-Aristotelian _Liber de proprietatibus elementorum_.[625] When William of Conches specifically denied the possibility of more than one deluge he may have had in mind the pagan association of Noah’s flood with the Great Winter.[626] Certainly one of the primary objections of the orthodox Christians to the acceptance of Aristotelian science during the early years of the thirteenth century lay in the fact that Averroës, the great interpreter of Aristotle, was firmly convinced that the universe is eternal.[627] William of Auvergne also vigorously attacked the Aristotelian theory as it found expression in Avicenna’s commentary on the _Metaphysics_[628] and Robert Grosseteste leveled destructive criticism against it in his _Summa super libros octo Physicorum_, a commentary on the _Physics_ of Aristotle, and in other works.[629]

BERNARD SYLVESTER’S ACCOUNT OF THE CREATION

Before leaving this aspect of the subject, a few words should be said about two other accounts of the Creation that found literary expression in Western Europe during our period. Very dissimilar, these two accounts are akin only in the circumstance that they were both based upon the mythology of an older age and that, though written by Christians, neither referred in any way to the Scriptural story. One was the remarkable allegory in Bernard Sylvester’s _De mundi universitate_, the other the Icelandic myth of the Creation as recorded in the _Edda_ of Snorri Sturluson.

In the _Megacosmus_, or first part of the _De mundi universitate_, Bernard tells us of the confusion of matter in the eternal ages that preceded the “Creation.”[630] Nature, personified, laments to “Nous,” or Providence, about this confusion and demands that the universe be put into an orderly condition: “Nous,” moved by the appeal, carries out the task, separating the elements, arranging the nine hierarchies of angels, placing the stars in the firmament and regulating their orbits, ordering the four winds, and, finally, fashioning the earth in the midst of the universe. The last process gave Bernard occasion to digress and to tell of the riches and beauties of this earth.

The _Microcosmus_, or second part of the book, goes on to relate the story of the creation of man. “Nous” sees the barren desolation of an inanimate world and orders Nature to undertake the work of peopling it. With the aid of Urania, goddess of the stars, Nature seeks for Physis, goddess of life, whom she finds in the terrestrial paradise after Urania has conducted her on a long journey through the heavenly spheres. Here she tells Physis her mission; and Physis carries out the fashioning of a human body, in which the soul is then established. Thus was man created.

No comment is needed to bring out the pagan character of this account, wherein the Six Days are not even mentioned! It would probably be wrong, however, to assume that this work of literary imagination, any more than Snorri’s graphic record of the beliefs of his forefathers, represents a formulated and accepted doctrine of its author.

THE ICELANDIC ACCOUNT

The Icelanders were converted to Christianity in the mid-eleventh century, and the mythology of their pagan days still remained fresh in their minds and hearts during the period we are studying. The old gods were looked upon with affection, and the old story of the Creation was remembered with sympathetic understanding. The Icelandic myth of the Creation is one of great beauty and vigor. In it is revealed the impression made upon the minds of a northern people by struggles against the cold and stormy darkness of the subarctic winter. The outline of the story, which is worked out in much detail in the _Eddas_, is about as follows.[631]

In the beginning a great abyss lay between the icy rivers and the drizzling rains and blasts of wind of the north and the blazing heat of the south. This was before heaven and earth and sea were made. “And Fimbultyr said: Let the melted drops of vapor quicken into life, and the giant Ymer was born in the midst of Ginungagap[632] [the abyss]. He was not a god but the father of all the race of evil giants. This was Chaos.

“And Fimbultyr said: Let Ymer be slain and let order be established. And straightway Odin and his brothers ... gave Ymer a mortal wound, and from his body they made the universe; from his flesh, the earth; from his blood, the sea; from his bones, the rocks; from his hair, the trees; from his skull, the vaulted heavens; from his eyebrows, the bulwark called Midgard. And the gods formed man and woman in their own image of two trees, and breathed into them the breath of life. Ask and Embla became living souls, and they received a garden in Midgard as a dwelling place for themselves and their children until the end of time. This was Cosmos” (Anderson).[633]

_MACROCOSM AND MICROCOSM_

All medieval accounts of the Creation culminate in the creation of man, as modern outlines of evolution conclude with man’s evolution from lower forms of life. Christian theology taught that the universe itself was made for man, a view that persists even to this day. Grosseteste asserted that when man “no longer requires the processes of generation and corruption which the movements of the heavens cause, the heaven itself will cease to move and time will be no longer.”[634] Rupert of Deutz explained that mountains were placed upon the earth to protect human beings against the winds.[635] But if the universe and all its parts were made for man, medieval thinkers held, with the Stoics of antiquity,[636] that man himself was a lesser universe (_minor mundus_), or microcosm, comprising all the elements both physical and spiritual which constitute the greater universe, or macrocosm.

EXPLANATION OF FIG. 5—The human figure here represents the microcosm
in the midst of the universe. The heads of the animals give rise to
the winds, which Hildegard believed controlled the movements of the
celestial bodies (see p. 171). The blast originating in the human
head at the right and moving in a counter-clockwise direction runs
opposite to the movement of the firmament. “This blast did not give
forth his breath earthward as did the other winds, but instead
thereof it governed the course of the planets” (_Liber div. op._,
in: Migne, _Pat. lat._, vol. cxcvii, col. 791, as cited by Singer,
_op. cit._ p. 28).

In another miniature from the same manuscript (fol. 9 ro) shown in
Singer, _op. cit._, pl. VII, the universe is revealed in much the
same manner with the human figure as the microcosm. There is also
represented the macrocosm, as a larger figure standing behind and
holding the sphere of the cosmos; only its head, feet, and hands
appear.

FIG. 5—The macrocosm, the microcosm, and the winds, from a miniature
in an illustrated codex of Hildegard of Bingen’s _Liber divinorum
operum_ in the Municipal Library at Lucca, fol. 27 vo. (Redrawn, by
permission, from Singer, _Scientific Views and Visions of Saint
Hildegard_, 1917, pl. VIII.) For explanation, see bottom of opposite
page.
]

The doctrine of man as the microcosm had its roots far back in antiquity. Medieval writers from the time of Isidore elaborated upon it with detail and ingenuity. In the literature of our period it occurs in many a passing comparison of the phenomena of nature with the human body, such as that of the _De imagine mundi_ where rivers are compared with blood vessels.[637] It forms an important element in the cosmology of Bernard Sylvester’s _De mundi universitate_[638] and of Herrad of Landsperg’s _Hortus deliciarum_.[639] Hildegard of Bingen’s writings are full of similes and medical recommendations based upon it (Fig. 5).[640] In her _Subtilitates_ the abbess says: “In the creation of man from the earth other earth was taken, and all the elements served man because they perceived that he lived; both the elements and man worked together to each others’ advantage in all relationships.”[641] The thought is expressed more clearly in the _Causae et curae_: “Oh, man! Look at man, for man has in himself heaven and earth and all other things that are created, and his form is one and in him all things lie hidden.”[642] To illustrate the detail in which Hildegard worked out this theory we may do no better than to quote from Thorndike’s summary. “She compares the firmament to man’s head, sun, moon, and stars to the eyes, air to hearing, the winds to smelling, dew to taste, and ‘the sides of the world’ to the arms and sense of touch. The earth is like the heart, and other creatures in the world are like the belly. In the _Liber divinorum operum_ she goes into further detail.... From the top of the cerebral cavity to the ‘last extremity of the forehead’ there are seven distinct and equal spaces, by which are signified the seven planets which are equidistant from one another in the firmament. An even more surprising assumption as to astronomical distances is involved in the comparison that as the three intervals between the top of the human head and the end of the throat and the navel and the groin are all equal, so are the spaces intervening between the highest firmament and lowest clouds and the earth’s surface and center.... As the heart is stirred by emotion, whether of joy or of sorrow, humors are excited in the lungs and breast which rise to the brain and are emitted through the eyes in the form of tears. And in like manner, when the moon begins to wax or wane, the firmament is disturbed by winds which raise fogs from the sea and other waters.”[643] The preface to the _Subtilitates_ contains another discussion of the microcosm in the course of which the stones of the earth are likened to bones and it is pointed out that the earth has sweat, humors, and other by-products of the body.[644] Much of the argument of the _Causae et curae_ is based upon the assumption that the very diseases of man have their counterparts in the facts of the macrocosm.

_SHAPE, MOVEMENTS, AND SIZE OF THE EARTH_

When once created, what form did this universe take, and the earth within it?

SPHERICITY OF THE UNIVERSE

Nearly all the authors of our period appear to have shared in the belief that the universe is a sphere and that the earth is situated in its center. Lambert of St. Omer says in his _Liber floridus_: “We say the earth is the center, that is, the point in the middle of the sphere.” “For the earth is located as a central point in the midst of the celestial circle through which the sun passes.”[645] Robert Grosseteste stated that the sphericity of the universe was necessitated by the nature of the substances composing the heavenly bodies and that it could be proved by simple astronomical observations.[646] There is, perhaps, an echo of Pythagorean mathematical doctrines in the exposition which we find in the _Image du monde_, that the world is round since God desired it to be so, because roundness is the most perfect of all forms.[647] Al-Farghānī, whose work was translated more than once during our period and formed the basis of much that is found in John of Holywood’s _De sphaera_,[648] had said that there was no difference of opinion among learned men that the universe was a sphere. That the earth is in the center of the heaven, he asserted, was shown by the fact that half the heaven is always visible from all parts of its surface.[649] The author of the _De imagine mundi_ had also thought the same way:[650] he compared the universe to a ball, or to an egg of which the shell corresponds to the upper heavens, the white, to the upper air, the yolk, to the lower air, and the _pinguedinis gutta_, or drop of grease in the center, to the earth.[651] Gervase of Tilbury,[652] who borrowed the idea from Comestor,[653] and the author of the _Image du monde_[654] make similar comparisons, although Peter Abelard,[655] William of Conches,[656] and Daniel of Morley conceived of the four parts of the egg as corresponding exactly to the four elements.[657] Michael Scot compared the earth, surrounded by water, to the yolk of an egg and the spheres of the universe to the layers of an onion.[658]

In her _Causae et curae_, on the one hand, and in her _Scivias_ and _Liber divinorum operum_, on the other, Hildegard of Bingen makes contradictory statements in regard to the position of the earth in relation to the heavenly spheres. Scientific consistency was not, perhaps, the ascetic abbess’s strongest quality, and too much emphasis should not be laid upon contradictions found in the writings of one who believed herself to be favored by special divine revelations. The passage in the _Causae et curae_, however, diverges so widely from current medieval opinion that it is worth translating. “The earth,” writes Hildegard, “is of moderate size and is near the base of the firmament, because if it were in the center of the firmament, then it would have to be larger; and even so it would easily fall and be shattered to pieces, had it the same expanse of air beneath that there is above.”[659] On the contrary, in her _Liber divinorum operum_ she tells how she saw in a vision the universe as a wheel[660] and that “in the midst of the air the earth was placed in such a way that the air measured an equal distance above the earth, below the earth, and on either side of the earth.”[661]

SHAPE OF THE EARTH

Most writers of the Crusading age thought the earth also was a sphere, though there was less unanimity in this belief. The _De imagine mundi_ calls it a sphere, whence comes the term _orbis_.[662] William of Conches[663] furnishes us with the Aristotelian proofs of sphericity. If the earth is flat, he says, it would be day at the same time in the farthest east as in the farthest west. Certain stars are visible in one latitude that cannot be seen in another, and this would not be the case if there were no curvature from north to south.[664] John of Holywood, following Al-Farghānī, gave two proofs that the earth is round and two that the water is round.[665] That there exists a swelling or curvature of the earth (_tumor terrae_), he says, is shown by the difference in the time of eclipses between places in the east and west as well as by differences in the visibility of stars.[666] The curvature of water surfaces is demonstrated by the fact that a person standing at the foot of a mast is frequently unable to see objects visible to somebody at the masthead. Furthermore, since water is a homogeneous body, all parts of it must partake of the nature of the whole. Therefore it follows that because a drop is round, the mass of the waters of the earth must also be spherical.[667]

Gervase of Tilbury has been accused of believing that the earth is square, though the evidence in the text of the _Otia imperialia_ on which this accusation is based is very slender; and other texts would seem to support the opposite contention, that he accepted the theory of sphericity.[668]

Two passages in the _Causae et curae_ of Hildegard can apparently be explained only on the supposition of a flat earth.[669] Hildegard seems also to have been haunted by the old belief that bulked so large in the imagination of Cosmas Indicopleustes,[670] the belief that the earth rises into an immense mountain in the north.[671] She asserted that this mountain prevented the light of the east from penetrating the darkness of the north and the darkness of the north from obscuring the light of the east. On the other hand, in her visions the abbess more than once saw the earth as a globe.[672]

In the writings of the mystic Hugh of St. Victor we have a typical medieval allegorical interpretation of the words of Scripture regarding the earth’s form, with instructions as to how a map of the world ought to be made.[673] Hugh compares the _orbis terrae_ to an “oblong circle,” or oval, drawn around the ark, touching each corner. An oval shape was necessitated by the rectangular ground plan of the ark. Within this oval the _mappa mundi_, or map of the world, is to be drawn, with the front of the ark facing the east, and its rear, the west. In the segment formed to the east, between the ark and the circle, is Paradise; in that to the west the resurrection will take place; the chosen will go to the right, and the damned to the left into Hell, which forms the segment toward the north. Beyond this “oblong circle” another circle is to be drawn to show the zones, and the space between the two is the atmosphere.

One hesitates to draw conclusions from this as to what shape Hugh imagined the earth to be; probably he himself had no very definite theory. The picture which his description seems to invoke in our minds is that of a flat oval earth covered by an ovoid heaven, and certainly it is in every respect inconsistent with belief in a spherical earth.

IMMOBILITY OF THE EARTH

However men may have thought about the shape of the earth, there was no questioning the fact that it stands immobile and firm. Doctrines like that of the Pythagorean Philolaus had no place in medieval thought.[674] The ignorant, nevertheless, were often puzzled by the problem of what supports the earth. The author of the _De imagine mundi_ was content uncritically to explain that no fulcrum or support is necessary for this purpose but that the “divine power” is all-sufficient.[675] He quoted the one hundred and third Psalm: “Who hast founded the earth upon its own bases: it shall not be moved for ever and ever.”

Theodoric of Chartres, Adelard of Bath, and John of Holywood, on the other hand, adduced proofs of the immobility of the earth which had been derived indirectly from Aristotle. Theodoric asserted[676] that the earth does not gain its compactness either from its inherent nature, because earth is actually observed on occasions to become mingled with air; or from the weight of the overlying atmosphere and sphere of fire, because these have no weight. What, then, keeps it from flying to pieces? Here Theodoric appealed to the Peripatetic reasoning that the circular motion of the heavens necessitates the existence of a solid and immovable body in the center.[677] All heavy bodies acquire their _substantia_, or solidity, from the motion of light bodies; and conversely light bodies derive their motion from heavy bodies.

The _Quaestiones naturales_ of Adelard of Bath is in the form of a dialogue between Adelard and a nephew who asks questions. The nephew was much puzzled by the fact that, whereas heavy objects like rocks need a piece of wood or other support to hold them up in the air, the earth as a whole, much the heaviest of all, requires no such support.[678] Adelard replies first that the earth does not fall because there would be no utility in its doing so; then he proceeds to show by a rational argument (_rationabiliter_) why the earth does not need a support. The principal quality of earth he says, is heaviness; heavy bodies naturally seek the lowest position (_infimum_); the lowest position of a spherical body like the universe is its center—though why this latter proposition is so, Adelard fails to make clear. At all events, the earth tends to seek the center of the universe, just as a stone thrown into an imaginary hole piercing the center of the earth would come to a halt there.[679] Since the center of the universe is one point, not several, the earth forms a single unit, not several; and for these reasons, moreover, the earth is stable and immobile.

John of Holywood explained[680] the same thing more briefly than Adelard by simply stating that the immobility of the earth is due to its weight, since it is the nature of all heavy things to seek the center of the universe and since the earth is the heaviest of all elements. Both Adelard’s and John of Holywood’s arguments suggest the Aristotelian doctrine of an equilibrium of forces around the center of the globe, though this doctrine is not cited in so many words. Like most medieval writers, Adelard and John seem only partially to have understood the obscure texts from which they derived their proofs and to have left out many links in their chains of reasoning.

SIZE OF THE EARTH

Though the geocentric hypothesis prevailed in the Middle Ages, there is plenty of evidence to show that the smallness of the earth in relation to the heavenly bodies was understood.[681] William of Conches had thought that the sun was eight times as big as the earth.[682] In the _Image du monde_ this theme is elaborated:[683] we are told that it would take more than a hundred years for a rock to fall from the heavens; that the earth is like a tiny star in comparison with the immensity of the cosmos and is one hundred and sixty-six and three-twentieths times smaller than the sun.[684] John of Holywood quoted Alfraganus (Al-Farghānī) to the effect that the smallest fixed star is larger than the earth[685] but that the dimensions of such a star are as but a point in the firmament. He argued that the extreme smallness of the earth is proved by the fact that it is possible to see the middle of the firmament (_medietas firmamenti_) not only from the center of the earth but also from the earth’s surface.[686] His argument, which certainly proves nothing as it stands, is evidently a confused reflection of Ptolemy’s reasoning in the _Almagest_.[687]

As to the actual size of our planet various figures were occasionally quoted. The _De imagine mundi_[688] gives Posidonius’ estimate of the circumference as 180,000 stades, or 12,052 miles (_duodecies mille millaria et quinquaginta duo_). The _Image du monde_,[689] however, gives 20,428 miles. Eratosthenes’ 252,000 stades appears in Lambert of St. Omer’s _Liber floridus_[690] and John of Holywood’s _De sphaera_.[691] In the latter work it is cited on the authority of Ambrose, Macrobius, “et Eristenis philosophorum,” along with a brief account of the great Alexandrian geographer’s method of measurement.

_ZONES, THE ANTIPODES, AND “CLIMATA”_

The surface of the terrestrial sphere, surrounded as it is by the heavens, is naturally subjected directly to the influence of the heavenly bodies. We must now examine those general phenomena of the globe as a whole which were conceived to be consequences of the earth’s shape and position in relation to the remainder of the universe, postponing for a later chapter the study of the more local features of the _oikoumene_ (or habited quarter), which also result from the same circumstances.

ZONES

The most primitive observation reveals the fact that the heavenly bodies in their course through the sky revolve around two points and mark out certain circles. Very elaborate and often admirable discussions of the celestial poles, Arctic and Antarctic circles, equator, tropics, and ecliptic, are to be found in the numerous astrological and astronomical works of our period.[692] The study of these matters was already a highly developed science, but except in its geographical bearing it does not fall within our province.

We saw in Chapter I that ancient astronomers had drawn imaginary circles around the terrestrial sphere corresponding to the circles of the heavens and had designated these lines as the boundaries of zones on the earth’s surface.[693] The classical theory of five zones, divided from each other by parallels of latitude, was accepted by the geographical writers of the twelfth and early thirteenth centuries, although, as in classical times, opinions diverged widely regarding the characteristics of each zone. All, however, believed that the two polar caps were cold and that the equatorial regions were hot. For example Bernard Sylvester says in his _De mundi universitate_:[694] Nous, or Providence, “encompassed the earth with five parallels; on the one hand the extremes are frozen, on the other the central portions are hot. Also she made temperate two zones by placing on both sides of them the coldness of the extremities and the course of the sun over the midst of the earth.”

UNINHABITABILITY OF POLAR CAPS AND EQUATORIAL ZONE

Furthermore, a widely prevalent but not universal theory made the polar caps and equatorial zones not only cold and hot but also uninhabitable. The author of the _De imagine mundi_[695] and Gervase of Tilbury[696] plagiarized what Isidore had written on this subject.[697] They called the five circles separating the zones and the zones themselves from north to south, respectively, _septentrionalis_ (our Arctic Circle and North Polar zone), _solstitialis_ (our Tropic of Cancer and North Temperate zone), _equinoctialis_ (our Equator and Torrid zone), _brumalis_—or _hyemalis_ according to Gervase—(our Tropic of Capricorn and South Temperate zone), and finally _australis_ (our Antarctic Circle and South Polar zone). Of these they thought that only _solstitialis_ was habitable. William of Conches likewise believed[698] in uninhabitable torrid and frigid zones, though he rejected the theory that in the heavens above the sphere of the moon there are qualities of heat and cold corresponding to those of the terrestrial zones.

AUSTRAL CONTINENT AND ANTIPODAL REGIONS

Speculation was rife as to what lay beyond the equatorial zone and in those mysterious parts of the earth of which man had no knowledge. Rumors and conjectures of an austral continent and of antipodal regions figure widely in the geographical literature of the age. A fourth continent beyond the equatorial ocean (or Mare Rubrum) is shown on all the Beatus maps. It is represented as a strip of land along the southernmost edge of the earth (see Figs. 2 and 4, pp. 69 and 123, above). A legend, taken from Isidore, informs us on the St. Sever map that “In addition to the three parts of the world, there is a fourth part beyond the ocean in the midst of the south and unknown to us on account of the heat of the sun. Within its confines the antipodeans are fabulously said to dwell.”[699] The Osma Beatus map locates the _skiapodes_, or sun-shade-footed men, here (see Fig. 4). Confusion between true antipodal regions on the opposite side of the world and an austral continent lying south of the equator was not uncommon in antiquity and during the Middle Ages.[700] Belief in the latter did not necessarily involve belief in a spherical earth, and it has been argued that the Roman cartographers (whose maps may have inspired Beatus) showed such a fourth continent south of the equator, even though they did not deem the question of the sphericity of the world worthy of serious consideration. The Beatus maps themselves may easily be reconciled with an implicit belief in a flat world disk.

While this may be true of the Beatus maps, it cannot be said of the _mappamundi_ of Lambert of St. Omer or of references to the antipodes elsewhere in the literature of our period where it is impossible to question the conviction in the cartographers’ or writers’ minds that the earth is a sphere.

On Lambert’s map the austral continent occupies half of the circle of the earth. A long legend explains,[701] in terms similar to those of the St. Sever Beatus map, that this region is unknown to mankind because of the sun’s heat; that philosophers say the antipodeans dwell here; and that winter prevails during our summer. In addition to the austral continent, Lambert indicates without a shadow of doubt his faith in the existence of other antipodal regions. A large island on the western margin of his map is labeled, “Here dwell the antipodeans, but they have a different night and opposite days.”[702] We know from other parts of the _Liber floridus_ that Lambert was strongly influenced by Macrobius. A Macrobian sketch of a spherical world showing the five zones is inserted in the Ghent and other manuscripts. This reference to the antipodes can only apply to the unknown regions on the opposite side of the globe, beyond the meridional ocean which, as we have seen in Chapter I, had been described by Crates of Mallos and popularized in Macrobius’ _In somnium Scipionis commentarius_ and in Martianus Capella’s _De nuptiis Philologiae et Mercurii_. Belief in a spherical world is essential to belief in these theories.

THE CRATESIAN THEORY

Crates of Mallos’ conception of the arrangement of the world, introduced to Western knowledge through the works of Macrobius and Capella, was well known in our period. William of Conches, Adelard of Bath, and Bernard Sylvester all show the influence of the Crates-Macrobian system in their belief in a great equatorial ocean.[703] Giraldus Cambrensis and the author of the _De imagine mundi_, by their explanation of the causes of the tides, make it plain that they accepted the same opinion. Geoffrey of St. Victor gives a clear exposition of it in his _Microcosmus_.[704] Robert Grosseteste adopts it in his _De sphaera_, explaining carefully the two seas that encircle the earth and calling the equatorial sea “Occeanus” and that which includes the poles “Amphitrites.” He believed that only one of the areas of land separated by these seas is inhabited.[705] The same idea is reflected in words of the _Image du monde_[706] to the effect that only a quarter of the earth’s surface is inhabited and in the recommendation to the reader in his imagination to cut the globe into four quarters like an apple and to think of the habitable part as occupying the surface of one of the quarters. Godfrey of Viterbo points out the significance of the golden ball of empire which formed part of the regal insignia of the Holy Roman Emperors upon which, he said, the fourfold division of the lands of the earth’s surface was shown.[707] Among the imperial treasures (_Reichskleinodien_) in Vienna the golden apple dating from the twelfth century is of this form. Two bands encircling the regal ball at right angles represent the Cratesian idea of oceans girdling the earth.[708]

In one version of the legend of St. Brandan there is a curious passage where not only the possibility of antipodal regions is indicated but the pious necessity of belief in such regions.[709] St. Brandan is here reported to have read in an old book that beneath this earth there is another world, where day prevails when it is night with us. Unable to accept such a story, Brandan burned the book in a fit of exasperation; and as a punishment for his incredulity God made him voyage nine years upon the seas. What the book was we are not informed, but perhaps we do not err in assuming that the poet had in mind a copy of the _In somnium Scipionis commentarius_ or possibly the _De nuptiis Philologiae et Mercurii_.

PERSISTENCE OF BELIEF THAT ANTIPODAL REGIONS WERE INHABITED

An essential feature of the theory as it had been expounded by Macrobius and Capella, however, was the insistence that the other three temperate areas are inhabited by races of men like our own. As belief in the existence of inhabitants in the antipodal regions rested in our period on the authority of Capella and Macrobius and was subjected to lively discussion and controversy, it is not out of place for us to observe what these two writers had actually said.

Capella, after briefly stating that three out of the five zones are uninhabitable on account of cold and heat, declared that the other two are tempered by a wind which encourages life.[710] The inhabitants of the quarter south of us, beyond the equator, he called _antoikoi_; those of the quarter also in the southern hemisphere but beyond the north-south ocean, who have winter when we have summer, _antichthones_. Those in our own temperate zone beyond the ocean, who have the same summer and winter as ours but who have night when we have day, he called _antipodes_.[711] No commerce or communication is possible between us and these other groups of human beings, nor between one group and any of the others. Macrobius set forth this theory in similar terms,[712] expressly emphasizing the point that reason teaches us that the southern zone must be inhabited because its climate is temperate like ours. However, he added, it is not peopled by men like ourselves—Greeks, Romans, barbarians—nor shall we ever be able to learn what sort of men the inhabitants actually are.

Though, as we have seen, out-and-out belief in antipodeans was heretical during the epoch we are studying, there is plenty of evidence to show that the possibility of such a thing was an attractive subject of speculation. The legends on the Lambert maps to which reference has been made above would alone be sufficient to convince us of this. William of Conches spoke very guardedly on the matter;[713] his avowed theory was that the other temperate regions were habitable but not actually inhabited. But are we not justified in thinking that in denying the existence of antipodeans he was merely making a verbal concession to theological prejudice, especially when he went on to explain that, if there were people dwelling in other quarters, they would be called _antoikoi_, _antipodes_, and _antichthones_, and that some would have summer when we have winter, others night when we have day?

Gervase of Tilbury relates a fanciful story which might be interpreted to show that he too liked to dally with the pleasing fancy that there may be antipodeans, even though elsewhere he rejects such a possibility. He tells of a cave in a mountain belonging to the domain of the castle of Bech in Great Britain.[714] From this there nearly always blew a violent wind; but once, when the wind did not happen to be blowing, a swineherd entered the cave to look for a breeding sow which had wandered in. Here he found an open plain with cultivated lands and harvesters bringing in their crops, and from the harvesters he recovered his sow. To this Gervase adds, “It was an extraordinary circumstance that wintry coldness coming from these subterranean harvest fields seemed to penetrate into our hemisphere, which phenomenon I think ought to be attributed to the sun’s absence and presence elsewhere.”[715]

MANEGOLD’S ARGUMENTS AGAINST THIS DOCTRINE

The most convincing proof of the persistence in the early twelfth century of a tendency to believe in antipodeans is furnished by the fact that Manegold in Alsace,[716] sometime after 1103, saw fit to write a vigorous pamphlet attacking a certain Wolfelm of Cologne, whom he accused of harboring an heretical opinion. Manegold’s _Contra Wolfelmum opusculum_ illustrates admirably the orthodox, or even obscurantist, point of view. He accused Wolfelm of adhering to Macrobius’ teachings about the four inhabited quarters of the earth. Granting that there are four such quarters, he demanded, how can the teachings of the Holy and Apostolic Church, buttressed by all the authority of the Fathers, the patriarchs, and the prophets from the earliest times, be true? And how can we believe the prophecies that the Savior will come to bring salvation to the entire human race, if these branches of the human race are cut off from the rest, as Macrobius would have it, by the zones and temperatures of the earth’s surface? How could the prophecy have been true, “All the ends of the earth will bow down before our God (_salutare Dei nostri_), if certain ends of the earth are inhabited by men to whom the voice of the prophets and the apostles could not reach through impassable tracts of water, of cold, and of heat?”[717]

HABITABILITY OF THE EQUATORIAL REGION

Macrobius’ theory was also contradicted from a position opposite to that of the orthodox churchmen. The study of Moslem astronomy brought to Europe the opinion that the equatorial zone itself was not only habitable but actually inhabited. In the preamble to the _Marseilles Tables_[718] of Raymond of Marseilles, which reproduces ideas expressed by the Spanish-Moslem astronomer Az-Zarqalī, we have an explanation of the current theory among “philosophers” of the uninhabitability of the polar and equatorial regions. The latter the author of the treatise refuses to believe because the city of Arin and the temple of “Jupiter Arenosus” are both known to lie within the equatorial zone. He proceeds then to explain why it is physically possible for the regions beyond the equator to be inhabited.

Peter Alphonsi,[719] also influenced by Arabic reasoning, argued that the existence of Arin on the equator was sufficient evidence of the habitability of the equatorial regions and gave a glowing account of the temperate climate and attractions of those parts of the world. Man can live throughout the entire area covered by the seven climates, he maintained, and, as his interpretation of ancient authorities led him to suppose that the first climate began at the equator, he was convinced that the equator also would support human life. On the other hand, he did not agree with the preamble to the _Marseilles Tables_, for he maintained that the parts of the earth in the southern hemisphere beyond Arin were not habitable. This was because the sun, on account of the eccentricity of its orbit, approaches much nearer the earth in those climes than it does in more northern latitudes. In this way he accounted for the excessive cold of the Arctic and polar regions and a (supposed) excessive heat of the trans-equatorial zones.

Plato of Tivoli’s translation of Al-Battānī’s work brought to Western knowledge another Arabic discussion of the probable characteristics of the areas of the earth’s surface unknown to man.[720] As to the equator, Al-Battānī said, it was uncertain whether men had actually been there or not. The climate, however, could not be excessively hot, because the sun in crossing the zenith, as it does twice a year between the tropics, does not remain directly overhead very long. Al-Battānī saw no reason why winters and summers should not be temperate in countries along the equator and believed that these latitudes must have, in fact, a climate not greatly unlike that of Aden and Yemen, which, however hot it may seem to the European, apparently did not impress the Arabs by its torridity. The unknown districts of the world, Al-Battānī went on to explain, comprise eleven-twelfths of the whole. Though no man had ever reached them, he thought it not irrational to suppose that they were like the known parts, for the sun and stars must pass across them and produce in the same way winter and summer, the tides of the sea, and animal and vegetable life.

GROSSETESTE ON THE HABITABLE PARTS OF THE EARTH

When we come to the close of our period, we find that Robert Grosseteste, bishop of Lincoln, and after him his more famous pupil Roger Bacon, like Peter Alphonsi, took over from the Moslems much geographical and astronomical lore which they interpreted and freely criticized.

In a book entitled _De lineis angulis et figuris_ Grosseteste elaborated some general principles relating to the incidence and reflection of rays from celestial bodies. The _De natura locorum_ is an attempt to show how far these principles may be used to account for various phenomena of the earth’s surface. Grosseteste conceived of celestial rays and influences as emanating in an infinite number of cones, or “pyramids,” as he called them, the apexes of which were the celestial bodies; the longer and more oblique these pyramids, the weaker the effect of the rays upon the earth’s surface and vice versa.[721]

Let us see how Robert applied the principle of the pyramids to explain conditions in the equatorial zone, in the southern hemisphere, and in the polar regions.

_The Equatorial Zone_

Logically the equatorial zone should be scorched and burnt by the sun because the pyramids are there the shortest and the angles at which the rays reach the earth approach nearest to a right angle. As a matter of fact, Robert had it on the authority of Ptolemy and Avicenna that, whereas the subtropical regions are intensely hot, the subequatorial zone is not only temperate but extremely temperate (_temperatissimus_); indeed, he said, theologians place Paradise under the equator in the Orient. A modification of the principle of the pyramids was therefore necessary. In his readiness to admit such modifications of rules that he had laid down, Robert showed an open-minded and a scientific spirit. In order to allow for the circumstance of a supposedly temperate equatorial region, he stated that the heat received during the daytime must be neutralized by the coolness of the nights, since day and night between the tropics are always approximately the same length, as they are in the latitudes of Europe during spring and autumn only.[722]

_The Southern Hemisphere_

The southern hemisphere, on the other hand, Robert thought to be uninhabitable on account of the intense heat of summer and bitter cold of winter. The excessive heat he ascribed to the fact that the eccentricity of the solar orbit around the earth brings the sun no less than five degrees nearer the earth during the southern summer than it approaches during the northern summer.[723] The pyramids, or lines of heat radiation, are therefore shorter and the heat is more intense.[724] Conversely the southern winter must be colder than that of the north because the sun at that season is farthest from the earth.

Granting a geocentric universe, this reasoning was sound though its consequences were exaggerated. It is quite true that the earth is nearer the sun in the summer of the southern than in the summer of the northern hemisphere, yet no extreme results flow from this circumstance, and there is no great difference in the amount of heat received by each hemisphere.[725]

An exaggerated idea of the differences in temperatures north and south of the equator led Robert,[726] and after him Roger Bacon,[727] to doubt the validity of the theory of the precession of the equinoxes. This phenomenon would inevitably produce a gradual shifting of the climatic conditions of the southern hemisphere to the northern, and, as a result, the latter would presumably in the course of time become uninhabitable. Since this seemed incredible to Grosseteste and Bacon, they were impelled to deny the possibility of its cause.

_The Polar Regions_

In discussing the climate and habitability of the polar regions,[728] Robert cites a work, _De vegetabilibus_ (erroneously ascribed to Aristotle in the Middle Ages) and a commentary upon it. Here the extraordinary view was expressed that no plants or animals could survive in the polar zone because the heat of the sun would burn them up! This view originated in the known fact that the sun shines continuously for half the year at the pole and at no time sinks very far below the horizon. The commentator pointed out that the sun never retires more than 23° out of sight and that it is capable of illuminating and heating the atmosphere at 18° below the horizon. The theory, however, failed to take into account the very important fact that the sun’s rays reach the polar regions at a sharply oblique angle and that consequently their powers of generating heat are limited. This circumstance together with the “observations and reasoning of Aristotle, Ptolemy, and other authorities” led the Bishop of Lincoln conclusively to reject the singular theory of the _De vegetabilibus_ and to attribute to the polar zones a climate that, in so far as it was dependent upon the disposition of the heavens, rendered these regions uninhabitable on account of the cold. Nevertheless, he recognized that there might be accidental local conditions, such as the presence of mountains of peculiar shape, capable in the polar regions of producing areas of intense heat or of delightfully temperate climate. But to this subject we shall revert in a later section devoted to the influence of mountains on climate.[729]