Chapter I: The Contribution of the Ancient World

_SOURCES_

THE PYTHAGOREANS, PLATO, AND ARISTOTLE

The earliest writers who dealt with geographical matters in a more or less scientific spirit were the Greeks of Ionia and the Pythagorean philosophers of Magna Graecia. Though their theories exerted no direct influence on the formation of medieval geography, they should not be entirely overlooked. Ionic geography gave many ideas to the later Greeks; Pythagorean thought brought to bear a strong influence on the Platonic cosmology, which reached the Middle Ages through the Latin translation of Plato’s _Timaeus_ made by Chalcidius early in the fifth century after Christ, and through the Platonists Martianus Capella and Macrobius. Until the middle of the twelfth century Plato, of all philosophers, held the strongest grip on medieval thought; after that time the influence of Aristotle became more potent in the framing of the scholastic conception of the universe. We must regard Plato and, even more, Aristotle as the indirect sources of most of the cosmological, physiographic, and meteorological knowledge which, elaborated by later writers of antiquity and by the Moslems, reached the Middle Ages at second hand. Among the many writings of Aristotle those which contain the most material of interest to the geographer are the _De caelo_ (Περὶ οὐρανοῦ) and the _Meteorology_. The former, in four books, treats of the properties of the heavenly bodies, of the elements, and of the earth. Translations of the _De caelo_ in the Middle Ages often went under the title _De caelo et mundo_.[1][2] The _Meteorology_, besides a detailed discussion of the phenomena of the atmosphere, includes many speculations on physical geography. Theories of cosmology also found expression in the _Physics_ and _De generatione et corruptione_.

Footnote 1:

The notes will be found at the back of the book grouped by chapters
and consecutively numbered within each chapter.

The scientific genius of the Alexandrian Greeks of the Hellenistic period showed itself in the work of men like Eratosthenes and Hipparchus. By them the mathematical and astronomical aspects of geography were developed with accuracy; but unfortunately, owing to the almost universal ignorance of Greek in the West, the products of their genius had little part in the molding of medieval theories.

ROMAN INFLUENCE ON GEOGRAPHY

The Roman conquests tended to discredit scientific investigations and to bring into favor works of a descriptive nature which would appeal to the military chief, the provincial governor, or man of the world—to the practical rather than speculative type of mind. Polybius regarded geography as an important auxiliary science to politics and history. The geographical portions of his history treat of the countries of the known world, their peoples and customs; he is not concerned with the size and shape of the earth nor with the determination of latitudes and longitudes. Strabo, writing at the time of Augustus, represents the culmination of the Polybian method; but his great and comprehensive work, though of first importance in the history of ancient geography, was not read at the time of the Crusades.

PTOLEMY

The Greek, or more purely scientific, attitude, however, did not completely succumb. Posidonius[3] in the first century before Christ reverted to the method of Eratosthenes; and with Marinus of Tyre and Claudius Ptolemy, in the reigns of Trajan and Hadrian, there came a revival of mathematical geography which almost, if not quite, equaled the high level reached by the Alexandrians[4]. Ptolemy was the author of two works, both of which were destined profoundly to modify the development of science in later ages. These were the _Mathematical Composition_ (or _Almagest_, as the Arabs called it), a treatise on astronomy, knowledge of which reached the medieval West through Moslem channels; and the _Geography_, a work which remained virtually unknown in Europe until the fifteenth century.

LATIN WRITERS: PLINY, SOLINUS, CAPELLA, MACROBIUS

Though the most fertile investigations were made by Greeks, Latin writers naturally influenced more directly medieval thought in the West. Of those who dealt with geographic matters in the strictly classical period Pliny the Elder (23–79 A. D.) and Seneca (3 B. C.-65 A. D.) were the most influential. The _Historia naturalis_ of Pliny, an ill-digested compilation of information of all sorts, contained books on geography that were destined to furnish the larger part of the lettered man’s geographical ideas during many centuries.[5] Pliny’s work was not merely extensively read but was used and plagiarized by other writers of possibly greater popularity. The most significant of these was Solinus,[6] a compiler of fables in the third century after Christ, whose _Collectanea rerum memorabilium_ consists almost entirely of borrowings from Pliny or from a book from which Pliny drew.[7] The geographical information in Isidore’s _Etymologiae_ is largely made up of quotations and paraphrases from Solinus. Seneca’s _Quaestiones naturales_[8] was also widely read and formed the source of the bulk of the meteorological lore of the Middle Ages.

Two Latin writers of the late Empire also contributed materially to the evolution of geographical knowledge, Martianus Capella (fourth or fifth century) and Macrobius (fifth century). Capella’s encyclopedic _De nuptiis Philologiae et Mercurii_ is an elaborate commentary on and exposition of the seven arts; the book dealing with geometry gives the author an opportunity of presenting a résumé of geography, more particularly in its mathematical aspects.[9] That Martianus Capella’s treatise enjoyed an immense popularity in the medieval period is indicated by the quantity of manuscripts extant and by the frequency with which we find it listed in the medieval library catalogues[10] that have been preserved. The general sketch of the distribution of land and water on the surface of the globe contained in Macrobius’ commentary on the _Somnium Scipionis_[11] of Cicero was often quoted at later periods and formed the basis for some of the extremely crude maps of the world used in the twelfth, thirteenth, and fourteenth centuries.

In the remainder of the present chapter a very general review will be given of the more important geographic ideas borrowed by the Western world in these centuries from Aristotle, Pliny, Solinus, Seneca, Martianus Capella, Macrobius, and some others, and an attempt will be made to indicate the relationship between the growth of these ideas and the broader evolution of ancient geography as a whole.

_THE HISTORY OF THE UNIVERSE_

ANCIENT COSMOGONY

Though it is not now regarded as lying strictly within the field of geography, the history of the evolution of theories about the origin of the earth is so closely allied to the history of geography that the two cannot well be dissociated. A marked antagonism inevitably arose between the usual Greek view, which regarded matter as eternal, and the Christian view, which was based on the first chapter of Genesis and conceived of the universe as created at a definite point in time or concurrently with time. The men of the Middle Ages tended to adhere strictly to the Christian opinion, for to have done otherwise would have been heretical. Nevertheless, the ancient theory was well known to Christians and exerted in its various forms no small influence on the development of certain phases of Christian thought.

CELESTIAL INFLUENCES

It was a deeply rooted belief of many classical thinkers that the events and conditions on this world and on all the regions below the sphere of the moon’s orbit are regulated by the heavenly bodies. Aristotle and his followers taught that the heavenly bodies themselves are made of an imperishable and incorruptible, almost divine, fifth element, ether, which distinguishes them from the four corruptible elements (fire, air, water, and earth) that constitute the immediate world of our senses.[12] By virtue of this semi-divine quality, it was argued, the sun, planets, and stars exert an all-powerful control over the earth around which they revolve—an absolutely determining control over all events both great and small.[13] From this fatalistic belief sprang the science of astrology, a science which throughout antiquity was held in equal esteem with astronomy.

The study of the movements of the celestial bodies revealed the fact that at some time in the distant future, sun, planets, and stars will bear exactly the same relative position one to another that they do at the present moment. Consequently, it was inferred that the influence exerted by them on the sublunar regions will at that time be exactly the same as it now is, and all the phenomena now apparent on the earth’s surface will be exactly repeated. They will be repeated not only once but an infinite number of times at periodic intervals in the future; similarly they have been repeated throughout infinite cycles in the past.[14]

COSMIC CYCLES: THE GREAT YEARS

This idea of cosmic cycles, or Great Years, appears to have originated in the Orient, possibly with the Chaldeans.[15] It was firmly established among the Ionian Greeks[16] and Pythagoreans,[17] from whom Plato adopted it. Many and various opinions prevailed about the violence and character of the changes produced by the celestial cycles. The Chaldeans had thought that whenever all the planets come into conjunction on one straight line in the sign of the zodiac Cancer, the entire universe is destroyed by fire but destroyed only to be born again; similarly the world is destroyed by water when the same phenomenon occurs in Capricorn.[18] The theory of a complete and universal birth and rebirth (_palingenesis_) was held by some of the Greek philosophers.[19] Plato and Aristotle, however, seem to have restricted the destructive effects of the celestial influence to the sublunar sphere and maintained that the realms above the moon were eternal.[20] On the whole, belief in periodically recurrent destructions of the earth by water was more widespread and was given greater definition than belief in corresponding destructions by fire.[21] The main reason for this is probably to be looked for in the dissemination among nearly all peoples of legends of a great flood, but it also in no small measure may be attributed to rudimentary geological observations (notably of the presence of shells on high ground) which showed that portions of the earth’s surface had at one time lain beneath the waters.[22]

GEOGRAPHIC APPLICATION OF THE THEORY OF THE GREAT YEARS

The theory of the Great Years was invoked to explain changes in geographic and climatic conditions on the earth’s surface.[23] When the various planets and stars bear a certain relation to one another, a period of dryness and heat, or a Great Summer, is experienced; conversely, when other stellar relationships prevail, there is a period of cold and wetness, or a Great Winter. Even land and sea gradually change places under stellar control. Certain parts of the land, Aristotle observed, had once been covered by the sea, and what is now sea had once been land: like plants and animals, land and sea grow to maturity and old age. If the causes adduced for these changes were not so utterly different from those that are now accepted, we might almost be tempted to think that Aristotle had some conception of climatic cycles and cycles of erosion.

After Plato and Aristotle, as before them, the doctrine of the Great Years, though by no means universal, was very popular in antiquity.[24] The Stoics adopted it in its more extreme form involving successive burnings and liquefactions of the universe.[25] It entered into Neoplatonism and was ultimately taken over by the Jews. It seems to have penetrated to India, where the Greek elaboration of the theory gave precision to ideas that were probably already in existence there. The Indian belief in the recurrent reincarnations of Brahma was brought into connection with Hellenic calculations of the duration of the Great Years.[26] From the Hindus and from the Greeks the conception was transferred to the Arabs and by them to the knowledge of the Latin West.

DURATION OF THE GREAT YEARS

Numerous endeavors were made in antiquity to calculate the length of a Great Year.[27] The figure that was adopted by the Arabs and passed on to the Christian world originated in Hipparchus’ discovery of the precession of the equinoxes, or apparent gradual revolution of the fixed stars around the pole of the ecliptic.[28] Ptolemy calculated that the period of this revolution was 36,000 years,[29] a figure which became known to the Hindus and Arabs and ultimately to medieval Christendom.[30] The actual figure is approximately 25,800 years.

_SHAPE, MOVEMENTS, AND SIZE OF THE EARTH_

SPHERICITY OF THE EARTH

Nearly all scholars of antiquity after the fifth century before Christ thought that the earth was a globe.[31] The earlier opinion of a disk-shaped earth resting upon the waters, which appears to have been held by Anaximander (although some students have thought that he, too, believed in a spherical earth [32]), was discarded by the Pythagoreans and Plato, and after their time no serious thinkers questioned the theory of sphericity. The Pythagoreans based their opinion on speculative and philosophical grounds rather than on physical and experimental proofs; they thought that since the sphere is the most perfect mathematical form, the earth must therefore be a sphere. The whole tendency of Aristotle’s thought, less speculative and less hypothetical than Plato’s,[33] led him to look for proofs of sphericity,[34] and these he enunciated with great emphasis. Cleomedes,[35] Pliny,[36] Ptolemy,[37] Martianus Capella,[38] and other ancient writers likewise adduced more or less convincing proofs, which were well known and often cited in the medieval period.

IMMOBILITY OF THE EARTH

Though the learned men of the ancient world were almost universally agreed that the earth is a globe, they were not unanimous in the belief that it stands immovable in the center of the universe; yet the various theories which diverged from this orthodox view had no place in the development of medieval cosmology until long after our period.[39] Certain among the Pythagoreans maintained that there is a fire in the heart of the earth.[40] Plato said that the center of the earth, which stands immobile[41] in the center of the universe, is the seat, not of a fire, but of the World Soul.[42] Through its own internal movement the World Soul causes the movement of the universe as a whole. Belief in the World Soul of Plato was extraordinarily tenacious, and it emerges in the writings of more than one Neoplatonist of the Middle Ages. Aristotle, however, though he likewise held fast to the doctrine of the immobility of the earth in the center of the universe, differed both from the Pythagoreans and from Plato in refusing to believe that the center of the universe could be the seat of an incorruptible being of the same substance as the celestial bodies, be it fire or World Soul. Aristotle,[43] Pliny,[44] and Ptolemy[45] also brought forward proofs of varying validity in favor of the immobility of the earth.

CIRCUMFERENCE OF THE EARTH

Several figures were given by ancient authors for the circumference of the earth. Aristotle stated it to be 400,000 stades;[46] Eratosthenes determined it to be 252,000 stades according to the testimony of many writers, including Pliny,[47] Vitruvius,[48] Martianus Capella,[49] and Macrobius,[50] although Cleomedes, who gives the most circumstantial account of Eratosthenes’ measurement, had said that the latter’s figure was 250,000.[51] It is probable that Eratosthenes himself arbitrarily added 2000 stades to his result in order to obtain a figure more easily divisible.[52] Cleomedes quotes Posidonius as giving 240,000 stades,[53] and Strabo says that the latter gave 180,000 stades.[54] The last number was that adopted by Marinus of Tyre and by Ptolemy.

Though we have several distinct figures cited by ancient writers, these assuredly do not indicate that as many distinct processes of measurement were carried out. The circumference given by Aristotle was a mere estimate; Eratosthenes’ result was the only one based on accurate measurements and calculations;[55] the two figures given by Posidonius may well have been derived from Eratosthenes, the larger arising from a mistaken interpretation or intentional alteration of the latter’s figure, and the smaller from the use of a longer stade.[56]

At all events, so far as we know, only one method was employed by the Greeks for determining the size of the earth. This consisted of finding on the same day of the year the meridian altitudes of the sun at two places supposed to be on the same meridian of longitude, the distance between which was known through itineraries. The angle between the two meridian altitudes was then assumed to bear the same relation to the circumference of the heavens as the distance between the two points of observation bore to the circumference of the earth. Cleomedes[57] and Martianus Capella[58] described how Eratosthenes carried out such observations in Egypt.

The figure determined by Eratosthenes is surprisingly accurate. Whether the stade used by him was 157.50[59] or 168[60] meters, as different modern scholars contend, the circumference according to his estimate would be 39,375 or 42,336 kilometers. In either case the error is seen to be very slight, the true circumference of the earth being about 40,000 kilometers.

_THE DISTRIBUTION OF HABITABLE REGIONS; ZONES; THE DISTRIBUTION OF LAND
AND WATER_

We see, then, that the writers of antiquity whose opinions were destined to mold the thought of the medieval period believed that the earth is a sphere, immovably fixed in the center of the universe. We must now examine their theories regarding the distribution of phenomena on the surface of the globe and the interaction of these phenomena. Of prime importance were their views concerning the distribution of habitable areas of land, but these were so closely bound up with the theory of climatic zones that it is absolutely necessary to understand what this theory was before going further, even though the subject of zones might more properly be included in the study of the atmosphere.

ZONES

Parmenides may have been the first to conceive of zones upon the earth’s surface corresponding to the zones into which the astronomers had divided the heavens. Eratosthenes is said to have been the first to place the theory of terrestrial zones upon a firmly scientific footing, “by determining exactly upon the sphere the position of the fixed circles which mark the limits of each zone” (Thalamas).[61] Ancient geographers set the number of terrestrial zones at five, though they differed as to the character of the climates within them. The general opinion—one which was shared by Aristotle—was that the polar caps and the equatorial regions were incapable of sustaining life, the first on account of cold, the second on account of heat. Despite the fact that the notion of the existence of a fiery belt between the tropics was challenged by Polybius and Posidonius, who had heard reports from expeditions in these regions, this notion persisted in the writings of Martianus Capella, Macrobius, and many others and exerted an extremely restrictive effect on the subsequent development of geographical knowledge and enterprise.

The majority of the ancient writers whose works were read in Christendom before 1300 also thought that the _oikoumene_, or portion of the earth inhabited by men of our kind, is completely surrounded by an ocean. This is a belief common to many early peoples.[62] In the Greek world we can trace it back to the Homeric and Hesiodic Ocean Stream and to the conceptions of early Ionian philosophers, who had gone so far as to maintain that the earth had been created out of water,[63] or at least that it was originally submerged beneath the ocean and had been brought forth through the evaporation of the water by sun and stars.[64] The theory of an encircling ocean was certainly held by Aristotle, Pliny,[65] Seneca, Macrobius, and Martianus Capella.

CRATES’ THEORY OF FOUR LAND MASSES

The two last-named writers set forth an elaboration of an opinion first held by the Pythagoreans and worked out in detail by Crates of Mallos in the second century before Christ, which gained great ascendancy over the minds of map makers and writers of the Middle Ages. They explained that the _oikoumene_ is one of four similar inhabited bodies of land on the surface of the globe. These bodies of land are separated from one another by two oceans which encircle the earth, one running east and west in the fiery equatorial regions, and one running north and south at right angles to the equatorial ocean. This idea, which we shall call the “Cratesian” theory after its foremost expositor, did not pass unchallenged either in antiquity or in the Christian period. Involving as it did the doctrine of the antipodes—people dwelling in quarters absolutely inaccessible to men of our race, eternally cut off from our _oikoumene_ by the fires of the equator and the terrors of the meridional ocean—the Cratesian theory provoked the indignation of the Fathers of the Church as containing the seeds of heresy.[66]

EXTENT OF THE “OIKOUMENE”

Aristotle, although he had derived from the Pythagoreans the theory of an uninhabitable torrid belt,[67] believed in a greater southward extension of our _oikoumene_ than would be possible in accordance with the Cratesian theory. He harbored no idea of the existence of another _oikoumene_ in the same latitude as ours. He says very clearly in the _De caelo_[68] that there is no great distance between India and Spain and hinted at the same opinion in the _Meteorology_.[69] Seneca[70] held similar views.

The opposite theory—which has been called the continental as opposed to the oceanic hypothesis[71]—that Africa and Asia extended unknown distances south and east and that the Atlantic and Indian Oceans, like the Caspian Sea, were enclosed basins—also had its adherents, among them Herodotus, Hipparchus, and, most significant of all, Ptolemy. But Ptolemy’s _Geography_, though its content was reflected in Arabic notions of the earth’s surface, had almost no readers in the Christian West until the fifteenth century, and the works of Herodotus and Hipparchus were unknown.

_PHYSICAL GEOGRAPHY_

ARISTOTLE, SENECA, AND PLINY

Among the writers of antiquity who dealt with physical geography only three can be said to have influenced twelfth- and early thirteenth-century thought to any marked degree. These were, first and foremost, Aristotle, the substance of whose _De caelo_ and _Meteorology_ had reached the West before the year 1187 through the borrowings and plagiarisms of later scholars and after that time could be read in translations from the Greek and Arabic. In the second place, Seneca’s _Quaestiones naturales_ was popular before the direct influence of the _De caelo_ and _Meteorology_ began to be felt. In the third place, as we have seen, the Elder Pliny’s _Historia naturalis_ was not only widely read in the original, but also much that it contained was familiar through the intermediary channels of Solinus, Isidore, Martianus Capella, and others. Aristotle, however, was the fundamental authority, for a large portion of the material in the books of the two Latin authors came from his treatises.

THE FOUR ELEMENTS

Most ancient authorities believed that the universe is composed of four elements, fire, air, water, and earth, arranged in concentric spheres. Theoretically, according to this view, the sphere of water should entirely enclose the earth. Practical observation shows that it covers the lower levels of the earth’s surface only. How to reconcile the theoretical conception with observed facts was a problem which, as we shall see, greatly puzzled geographers and physicists during the later Middle Ages.[72]

According to Aristotle the four elements, under the control of the heavenly bodies and through their interaction upon each other, produce all the physical phenomena of the atmosphere, sea, and earth.[73] Working from this axiom, he, and all the ancient writers who dealt with the subject, attempted to explain winds, tides, earthquakes, and other occurrences of nature; but there was little agreement among them as to the manner in which these interactions were manifested. Though there were many theories, the actual matters under discussion were not very numerous. Only the most striking and unusual happenings—such as tides, earthquakes, and floods—attracted attention, and we find almost no trace of a minute and careful observation or even of a superficial understanding of those imperceptibly slow natural forces which modern geology recognizes as having fashioned mountains, rivers, and seas.

A logical division of the subject matter of physical geography is into three studies: that of the atmosphere, that of the waters, and that of the earth. In each of these there is room for a great deal of hairsplitting about what belongs to geography and what to geology, geophysics, or meteorology. Physical geography merges into the other natural sciences as human geography merges into history, politics, economics, or ethnology. Even at the present day, when the often futile attempt is being made to delimit the domains of the various sciences ever more definitely, it is impossible to distinguish where one begins and another ends, and it would be foolish to set up hard and fast definitions in dealing with the lore of the ancient and medieval worlds, when natural science was as yet inchoate.

METEOROLOGY

The ancients were more interested in meteorology[74] than they were in oceanography and physiography (if such terms can be used for their naïve attempts at explaining the features of ocean and land), perhaps because the phenomena of the air make a deeper impression on men than the phenomena of the sea and earth—tides, earthquakes, and volcanoes excepted. Thunder and lightning, comets, rainbows, balls of fire were looked upon as portents, and complex theories were created to explain them and what they were supposed to foretell. But all this type of meteorological lore, however interesting in itself, is, strictly speaking, not geography. On the other hand, there are certain distinctly geographical aspects of the study of the atmosphere as pursued by the Greeks and Romans that deserve our attention.

The men of antiquity conceived of the interaction of atmosphere and earth in two ways: effects produced by the land upon the atmosphere, and effects produced by the winds upon the land. In connection with the first, Seneca makes a remark which, when taken from its context, would not be out of place in a modern manual of meteorology. He conceived the lower portion of the atmosphere to be extremely variable and inconstant as a result of the proximity of the earth. “The earth is a more important cause than all others ... for the air’s changefulness and inconstancy. The varying positions of the land, facing here this way and there another way, are of great moment in determining the temperature of the air.”[75] Nothing is truer than this, but the reasons that Seneca gives for the influence of the atmosphere upon the land are not satisfactory, being based to a large extent on the supposition that winds are produced by vapors. Indeed, by the theory of vapors and exhalations many ancient and medieval thinkers attempted to explain nearly all the phenomena of the atmosphere and heavens as well. Aristotle had pointed out that a dry and smokelike exhalation is caused by the sun to rise from the earth’s surface through the air and even to penetrate the zone of fire.[76] While near the earth this exhalation takes the form of wind; when ignited at higher levels it becomes comets and shooting stars. Besides this, Aristotle maintained that a damp and watery vapor is also drawn into the atmosphere by the sun’s heat and when cooled turns into cloud or falls in the form of rain and snow.[77] These ideas of Aristotle became known to the Western world of the Middle Ages with translations of the _De caelo_ and _Meteorology_ and found their expression in the thirteenth-century writings of Albertus Magnus.[78] Seneca, on the other hand, explained that the winds were air in motion and that they might be produced by many and various causes.[79]

WINDS

All three of the writers whom we are specially considering,[80] Aristotle, Seneca, and Pliny, had observed that there is a variety of local winds—valley, river, sea, and marsh breezes—taking their origin from the exhalations and vapors arising from these natural features. But even though their explanations of the causes for these winds are now regarded as archaic, the observations they made of their occurrence were not inaccurate.

As to the effects of the winds on the earth, we encounter a theory that sounds most extraordinary in the light of modern science but which corresponds logically to the Aristotelian hypothesis of the elements and to the general ideas current in classical times regarding the structure of the earth. This theory, that the winds are the cause of earthquakes, can better be understood after we have examined the ancient opinions about the physical geography of the water and of the earth.

Another persistent belief, held alike by poets, physicists, and geographers, originated in the Homeric mythology of the calm heights of Olympus, dwelling place of the gods. This was to the effect that the winds are limited to the lower part of the atmosphere,[81] a zone some ten or fifteen stades in thickness.[82] The highest mountains were thought to reach above into a realm of perpetual tranquillity where clouds and dew and frost were unknown and where the ashes of sacrifice would remain undisturbed for a year’s time.[83] This idea was transferred to the Middle Ages through the writings of Pomponius Mela, Solinus, and others.

CLIMATOLOGY

As to the climates, it has already been shown that many writers of antiquity divided the earth’s surface into zones: fiery, temperate, and frozen. Aristotle, Seneca, and Pliny do not seem to have had that more exact understanding of the distribution of climates which recognizes that two countries in the same latitude may, nevertheless, have different climatic conditions and products.[84] To them, all places on the same parallel were virtually the same from the climatic point of view. In this connection it must be pointed out that the parallel strips, or _climata_, into which Eratosthenes, Hipparchus, Ptolemy, Pliny, and Martianus Capella divided the _oikoumene_ were not climatic divisions in our modern sense—implying the prevalence of well-defined conditions of temperature and weather—but, rather, artificial astronomical divisions the boundaries of which were determined by arbitrary means.[85] Nevertheless, true climatic differences were well understood; Seneca describes vividly in more than one place in the _Quaestiones naturales_ the intense heat and dryness of southern regions[86] and the cold of the far North; Seneca and Pliny had acquired more detailed knowledge than Aristotle of the northern ice and snows.[87] Pliny made some interesting, if unsound, observations connecting the dark complexions of the Ethiopians with the scorching effects of the sun and foreshadowed a modern theory by asserting that the inhabitants of northern Europe are blonde (and savage) because of the coldness and inclemency of the climate in which they dwell.[88] A brief but striking passage from the _Octavius_ of Marcus Minutius Felix explains as follows the warming effect of the western ocean upon the climate of Britain: “God is mindful of our welfare not only universally but locally. Britain is deficient in sunshine, but this deficiency is made good by the warmth of the sea that flows around it.”[89]

The Greeks and Romans certainly had no satisfactory understanding of the general circulation of the atmosphere. Only with the maritime voyages since the fifteenth century have we come to know the distribution of belts of prevailing winds and calms. Aristotle said that the etesian, or north, winds blow from the cold countries full of water and snow under the Great Bear; and that the south wind originates at, but not south of, the Tropic of Cancer;[90] this is the nearest he came to giving a theory of atmospheric circulation. Megasthenes had heard of the monsoons of the Indian Ocean; Pliny described the use made of them by sailors in going out to India,[91] but he made no attempt to explain the general areas of westerlies or trades. On the other hand, Aristotle,[92] Seneca,[93] and Pliny[94] all recognized and discussed at considerable length the influences of wind on weather; for example, the fact that the etesians, though they bring clear skies to Italy, deluge Ethiopia and India with rain—a conception which contains a shadow of truth.[95] Auster, the south wind, was supposed to bring rain to Italy.

THE WATER ELEMENT

Since water was one of the four—or, according to Aristotle, five—elements that were supposed to make up the universe, the ancient authorities looked upon the ocean as necessarily as old as the earth itself. Seneca thought that the Nile and the Ister (Danube) are of equal age with the primordial ocean, because of remarkable characteristics which differentiate them from all other streams.[96]

THE SEA: ITS SALINITY, DEPTH, CURRENTS, AND TIDES

We must note what features of the sea interested the Greeks and Romans. These were primarily its saltness, its depth, its currents, and its tides.

The problem of why the sea is salt gave rise to a good deal of theorizing. That the evaporation of the lighter fresh water leaves behind the heavy salt water was well understood, but in the further solution of the problem opinions diverged widely. Aristotle thought that the salt was the result of combustion;[97] that it was an ashlike substance first carried into the air by the exhalations from the earth and then deposited in the sea by rainfall—particularly by the autumn rains that accompany the south winds blowing from hot, dry districts where the process of combustion is most active. Pliny believed that the salt came partly from dry vapors intermingled with the sea waters and partly from the nature of the earth, which tends to impregnate the sea with salt.[98]

Aristotle said[99] that the Pontus (Black Sea) was deeper than the Maeotis (Sea of Azov), the Aegean deeper than the Pontus—except in one place—the Sicilian Sea deeper than the Aegean, and the Sardinian and Tyrrhenian the deepest of all seas. Pliny quotes[100] a certain Fabianus to the effect that the greatest known depth of the sea is fifteen stades, or about 1200 fathoms—not an excessive figure, for parts of the Mediterranean are in fact even deeper. Pliny,[101] following Aristotle,[102] believed that the “Deeps of the Euxine,” opposite the shores of the people of the Coraxi, were unfathomable.[103] Aristotle had a very false idea that the Atlantic is made up of shallows and mud banks and that it is calm, an idea shared by the Mohammedans and one that may have contributed to the horror of the Western Ocean which lingered in the minds of Mediterranean peoples throughout antiquity and until the close of the Middle Ages.[104]

The ancient geographers certainly had no clearer understanding of the general circulation of the ocean than of the atmosphere, and for the very same reason: they had not traveled sufficiently. Aristotle thought that there is a flow of water southward from the higher northern part of the earth,[105] and Macrobius explained a series of currents in the oceanic belts which he imagined surrounded the earth.[106] Certain currents of the Mediterranean attracted attention: the constant flow from the Euxine into the Aegean and the fluctuating currents of the Strait of Messina and the Euripus (between Euboea and the mainland). A tradition arose at later times that the death of Aristotle was caused by his disgust at being unable to explain to his satisfaction the currents of the Euripus.[107]

Only with the travels of Pytheas of Marseilles along the North Atlantic coasts, the expedition of Alexander, and Nearchus’ voyage and exploration of the mouths of the Indus and coasts of Beluchistan and Mekran did the Greeks gain any adequate knowledge of tidal phenomena; for the tides of the Mediterranean, except in a few places, are so low as to be almost negligible.[108] Eratosthenes thought that the currents through narrows in the Mediterranean are caused by variations in the relative levels of the sea at either end of the channels and that these variations are a response of the sea to fluctuations of the tides in the ocean beyond the Pillars of Hercules.[109] As early as the third century before the Christian era the Greeks had understood the relation of the moon’s phases to the ebb and flood, but certainly not much earlier, for Aristotle appears to have been ignorant of it.[110] Posidonius was the first to give a full account of the manner in which the moon and sun regulate the tides.[111] He had accurate knowledge of the diurnal, the monthly, and perhaps the annual tidal periods,[112] a knowledge which formed a bulwark of the structure of his astrology. Pliny also believed that the tides were caused by lunar influence and described the three periods with even greater accuracy than Posidonius.[113] He recognized that the tides must correspond to a lunisolar cycle of one hundred lunations, or eight years, an astronomical cycle that had long been familiar to the Greeks.[114] He included in his account an astute observation that the tides, like everything else on the earth’s surface depending on celestial controls, tend to drag behind the time when these controls are exerted.[115] Seneca does not try to explain the tides; he mentions them only incidentally in connection with a graphic description of the terrible deluge that will overwhelm the earth at the end of the Great Winter. Though in some respects like the spring tides at the equinoxes, when the sun and moon are in conjunction, this flood will be bound by no law of nature and will have no curb to its fury.[116] Macrobius’ explanation of the tides,[117] which was copied by many later writers, though ingenious, was not founded on actual knowledge or observation. He said that the ebb and flood are caused by the impact of the opposing currents of the two ocean belts which encircle the earth, and, with Eratosthenes, he thought that the tide of the Mediterranean is a repercussion of the ocean tides. Indeed, after the time of Pliny there was no addition to the scientific understanding of tidal phenomena until the eighth century.

SUBTERRANEAN CHANNELS

Evaporation was given by Aristotle as a reason why the sea does not overflow its bed on account of the constant inflow from the rivers.[118] Another explanation of this puzzling circumstance was found by Pliny[119] in a curious theory that prevailed throughout antiquity and the Middle Ages to the effect that the land is seamed with veins, cavities, and tunnels.[120] Into some of these the air enters; others are the passages for rivers which sink into the ground; through still others the water of the sea finds its way to wells, springs, and fountains, where, made fresh by its passage through the earth, it bursts forth to form rivers which return it to the sea. A continuous circulation of the waters of the earth is thus maintained through passages corresponding to the veins, arteries, and canals of the human body.[121]

The origin of the latter theory is undoubtedly to be sought for partly in the nature of the ground in Greece and the Aegean region and partly in the age-old belief that the interior of the earth is the abode of the dead.

The soluble character of the limestone rocks throughout parts of the Balkan Peninsula has led to the production of what is now known as _karst_ topography, so called from the Karst, a plateau between Trieste and Fiume, where it has attained its most typical development. In such regions many streams disappear into hollows of the ground; caverns and underground galleries are extremely common; and the traveler occasionally comes across a full-grown river bursting out of the depths of the earth. The old and persistent story that the river Alpheus of the Peloponnesus passes beneath the Ionian Sea only to gush forth in the well of Arethusa in Syracuse was destined to have a medieval counterpart in the explanation of the subterranean courses of the rivers of Paradise.

RIVERS OF THE UNDERWORLD

Among the most famous and sinister of the subterranean streams of antiquity were the dark waters of Cocytus, Acheron, Pyriphlegethon, and Styx.[122] These were the streams of the nether world, the world of the dead. Belief in the subterranean position of the after-world, the Hades of the Greeks, the Inferi of the Italian folk, was widespread and lasting among early Mediterranean peoples. Hellenic mythology placed not only Tartarus, the abyss of torment, but also the Elysian Fields in the depths. Plato taught that within the bowels of the earth are immense caverns, some filled with fire, some with water, others the abode of the shades. To be sure, rationalistic arguments against such doctrines were raised by the incredulous. Aristotle had believed that of all four elements the earth is the most dense and solid and that its position is at the center of the universe. Although the earth might be seamed with small water channels, it would be a reversal of the physical laws of the universe to suppose that within it there could exist caverns large enough to “hold Tartarus, the Elysian Fields, and the infinite multitude of the dead” (Cumont).[123] Hence some would identify the Elysian Fields with the Islands of the Blessed, placing them in the antipodes, and would relegate Tartarus to the lowest hollow of the celestial sphere.[124] But even this explanation could not be reconciled with the more mature cosmography of the Alexandrian age. The Epicureans resorted to out-and-out disbelief in a future life and future dwelling place of the spirit.[125] Others looked for the shades in the atmosphere below the moon’s orbit or else treated the whole problem in a lofty vein of allegory. Rationalistic questioning of the subterranean position of the next world, however, did not shake faith in this doctrine as it persisted among the ignorant, and the doctrine was given new life, if in somewhat different forms, by the Neoplatonic movement and the influx of Oriental cults during the waning years of the Western Empire.[126] The Neoplatonists reverted to Plato’s theory that the interior of the earth may well include hollows large enough to contain the future abode of men’s souls. The religion of Mithras tended to spread throughout the Occident the dualistic cosmology of an eternal conflict between the powers of light and goodness on high and the powers of darkness and evil below. In the words of Franz Cumont, whose truly fascinating study of this subject we are here following: Oriental dualism cut “the abode of the souls into two halves, of which it placed one in the luminous sky and the other in subterranean darkness. This was also the conception which, after some hesitation, became generally accepted by the Church and which for long centuries was to remain the common faith of Christendom.”[127] In the period with which it is our special problem to deal, then, we shall find that Hell is almost invariably placed in the heart of the earth.[128]

ORIGIN OF RIVERS

To return from this digression to the vexed question of the origin of super-terrestrial rivers, we find that the circulation of water from the sea either by underground passages or by rain was not regarded by the majority of ancient thinkers as sufficient to account for the huge volumes of water that rivers constantly pour into the sea. Plato had thought that there were enormous reservoirs in the interior of the earth which served to keep the rivers supplied,[129] but Aristotle rejected this hypothesis.[130] A reservoir as large as the entire earth, he said, would be necessary for the purpose. His explanation was worked out of the theory that one element actually may be transformed into another. In a relatively unscientific age what is more natural than to believe, when one sees soluble substances passing into solution in water, that they actually become water? Or when one sees the condensation of invisible vapor into clouds and of clouds into rain, that the air is actually turning to water? Aristotle, followed by Seneca,[131] argued that the air which penetrates into the internal cavities and recesses of the earth is chilled and liquefied by the cold encountered there, just as air seems to be condensed by cold in the outer atmosphere. Aristotle cited as a proof of this the supposed fact that most great rivers have their sources in mountains.[132] Mountains were to be looked upon as enormous elevated sponges exuding water on all sides. Aristotle concluded likewise that the northern part of the earth must be high and mountainous,[133] because many great rivers originate there. But, if the air is transmutable into water, why, then, was it not perfectly logical to suppose that the earth could also undergo a similar change? This as a theory to explain the origin of some of the water of rivers was clearly expressed by Seneca and, among the early Church Fathers, by Gregory of Nyssa.[134] The faulty character of Seneca’s scientific thought is seen in his failure to account satisfactorily for the logical demands of his theory, i. e. for the replacement of the land lost by its liquefaction.

THE NILE FLOOD

One of the natural phenomena most puzzling to the Greeks and Romans was the inundation of the Nile.[135] Herodotus in his famous book on Egypt had given a lengthy account of the Nile and what it meant to Egypt. He had called Egypt the “gift of the Nile,” for he understood the alluvial character of the country. His theory as to the cause of the flood—he held that the normal height of the river was its flood height but that the etesian winds, by driving the sun southward out of its course in winter, caused the sun to dry up the headwaters of the stream—was less successful than his description of the features of the flood itself. Seneca also gives a long and extremely picturesque description of the inundation[136] and sets forth various older explanations of its origin, all of which he tries to refute without presenting an opinion of his own. He tells how, starting in the upper reaches of the river, the flood travels downstream and arrives in Egypt about midsummer; how it adds to the fertility of the country by its deposits of silt; and how—here Seneca repeats the crisp phrase of Herodotus—Egypt is the creation of its stream. Among the various theories which he comments upon and refutes it is rather significant to find one which had been propounded by Anaxagoras and which is now recognized, in part at least, as the right explanation: that the high water is caused by the melting of the snows on the Ethiopian mountains. Seneca said that there were twenty proofs available to refute this hypothesis.[137] Another view which Seneca rejected was that the flood was caused by the etesian winds backing up the water, a theory fated to reappear in many medieval books, among them the _Expositio in hexaemeron_ of Peter Abelard.[138] Pliny discussed the Nile and its peculiarities.[139] Like Herodotus, he believed that it rises in the western part of Africa and reaches the Sudan and Upper Egypt only after a series of long subterranean journeys. He described the flood, giving statistics of the various heights of the water on the nilometer and explaining which heights meant plenty and which meant famine. He shows a lack of critical sense in his remarks on the causes of the high water; for he held that two theories are equally worthy of credence, the theory of the etesian wind, which we have just examined, and the true explanation that the floods are due to summer rains in Ethiopia.

THE LANDS

To turn now from water to land. We have already discussed Aristotle’s idea of the gradual transposition of continents and oceans under the control of the celestial bodies. Pliny describes a large number of local changes of land and sea:[140] the building of new land by alluvial deposits, the sudden appearance of land and islands out of the depths of the waters, the separation of islands from the mainland, the tying of islands to the shore, the total disappearance of entire countries beneath the sea—Plato’s Atlantis is given as an example[141]—the collapse of mountains; but in all this, though he tells where such prodigies took place, he rarely tries to explain how and why they happened.

EARTHQUAKES AND VOLCANOES

The explanation of the causes of earthquakes and volcanoes, however, was attempted by Plato, Aristotle, Pliny, Seneca, and many other writers of antiquity with no small measure of ingenuity. We have seen that ancient philosophers almost universally were of the opinion that the earth is honeycombed with cavities and subterranean passages. Plato said that some of these cavities were filled with water and air but that others contained mighty swamps and streams of fire, including the immense fiery river Pyriphlegethon. The volcanoes of the earth’s surface were outpourings from these internal streams, and their minglings with the atmosphere and strivings to burst forth were the cause of earthquakes.[142] Aristotle, on the other hand, denied the possibility of subterranean fires. According to his scheme of physics the place for fire in the universe was above the sphere of air. He maintained that the dry and smokelike exhalation which causes the winds of the atmosphere not only penetrates into the cavities of the earth from the outside but is generated within the earth’s interior[143] and that when this exhalation tries to escape and is opposed by any obstacle—for example, by the sea—there is a tremendous upheaval and the land is shaken. Seneca[144] and Pliny[145] ascribed the cause of earthquakes to the winds. Pliny believed that after a great storm, in which wind is driven down and compressed in the interior of the earth, it frequently strives to come forth and in so doing shakes the earth’s surface far and wide. Occasionally, if the pressure is too tremendous to be withstood by the crust of the earth, the winds burst through, accompanied by a violent tempest and a rain of sparks and cinders. Aristotle describes such a volcanic eruption in the Eolian (Lipari) Isles.[146] While this was the explanation of violent eruptions, the quiescent volcanic activity of mountains like Etna was usually attributed to a different cause. Pliny[147] speaks of Etna, Chimaera in Lycia, and various other volcanoes as burning, and it would seem that he connected them with such phenomena as burning naphtha wells and pits of bitumen and sulphur.

HEIGHT OF MOUNTAINS

A word must be said about classical estimates of the height of mountains.[148] Aristotle suggested that these altitudes might be determined by observing the duration of sunlight on the peaks. He would have us believe that the Caucasus range is illumined by the sun for a third of the night after sunset and for a corresponding time before sunrise. If this were true, these mountains would be from 60 to 180 miles high![149] Less fantastic were the estimates of Dicaearchus and Eratosthenes. The former, Pliny tells us, measured Pelion and found it to be 1250 paces (10 stades) in height.[150] If we are right in our understanding of the length of the pace here employed, this represents 5167 feet[151]—certainly not far short of the actual altitude (5308 feet). We do not know the method used by Dicaearchus in this survey, but his calculation was probably determined from simple triangulation with the aid of a diopter, an instrument for measuring angles.[152] Triangulation as a means of finding the height of trees and buildings was well understood. Eratosthenes probably did not carry out a triangulation of his own but adopted the results obtained by Dicaearchus, asserting that the highest mountains in the world do not exceed 10 stades in elevation. He demonstrated by an ingenious and graphic mathematical proof that the volume of mountains is so utterly insignificant in comparison with the volume of the earth as a whole that the earth can be regarded as essentially a sphere,[153] a conception which became well established in the astronomical thought of antiquity and one which reappeared in the Middle Ages.[154] When the Greeks learned something of the Alps, they were able to correct Eratosthenes’ underestimate of the maximum height of mountains. Posidonius argued that 15 instead of 10 stades should be taken as the correct figure and that the maximum depth of the sea was no greater than 15 stades.[155]

_MATHEMATICAL GEOGRAPHY AND CARTOGRAPHY_

Mathematical geography deals in part with the accurate determination of the location of places and with the accurate representation of the earth’s surface on maps.

MATHEMATICAL GEOGRAPHY LARGELY BASED ON ITINERARIES

The method almost universally employed by ancient geographers for determining locations was the compilation of itineraries; the position of a place was found, not by accurate surveys, but by reference to other places at so many stades or so many days’ journey in such and such a direction. Whatever maps the Romans may have had (for example the great representation of the Empire set up by Agrippa in the Porticus Octaviae in Rome) were probably compiled entirely from route traverses. The greater part of the information which even the most accurate and scientific of the Greek geographers, Eratosthenes, Marinus of Tyre, and Ptolemy, possessed, was drawn from such itineraries and from estimates of sea voyages. The figures for the latitude and the longitude of the large number of places given in Ptolemy’s _Geography_ are for the most part not the result of astronomical observations, and the tables cannot be regarded as analogous to modern tables of latitudes and longitudes but must be considered rather as guides for the construction of maps.[156]

Other methods besides these simple reckonings of locations were well known, none the less.

ASTRONOMICAL DETERMINATION OF LATITUDE

The determination of latitude has always been a comparatively easy astronomical problem. No complicated instruments are needed to measure either the vertical elevation of the sun on the meridian or of the north celestial pole, and from both of these the latitude of the observer can be calculated with extreme accuracy. The instrument commonly used by the Greeks for measuring the angle of the sun[157] consisted of an hemispherical bowl (_scaphe_) with a vertical rod (_gnomon_) for a radius. The shadow of the rod on the concave interior of the bowl gives the elevation of the sun (with an error of 16′[158]) and thereby the latitude. Eratosthenes, Hipparchus, and Ptolemy were all familiar with the latitudes of several places that had thus been determined.

ASTRONOMICAL DETERMINATION OF LONGITUDE

To find longitude by astronomical means is a more difficult matter for people who have neither chronometers nor telegraphs. Eratosthenes, Hipparchus, Pliny, and Ptolemy all understood that it may be found by observing the time of eclipses in different localities.[159] Hipparchus believed that an extensive series of observations should be carried out in order to ascertain, by mathematical and astronomical means alone, latitudes and longitudes of a large number of places.[160] To facilitate such a survey he prepared tables of lunar eclipses and tables to aid in the determination of latitudes, but the practical difficulties of the undertaking were too great and the work was never completed. In fact, throughout antiquity the total number of places whose position had thus been accurately determined probably does not exceed half a dozen, if it is as many.

Pliny gives[161] an account of two different occasions when observations were made of the same eclipse at two different places. He says that at the time of the battle of Arbela the moon was eclipsed at the second hour of the night, when at the same hour it was rising in Sicily. He also speaks of an eclipse of the sun that was seen in Campania between the seventh and eighth hours and in Armenia between the eleventh and twelfth, indicating a difference in longitude of four hours, or 60°. The actual distance is no more than half of this. Ptolemy also cites[162] the eclipse of 331 B. C. as giving the distance between Carthage and Arbela. We shall see later that much greater accuracy was attained by the Arabs in their calculations of longitude and that some of their figures were passed on to the Western world in astronomical tables during the twelfth and thirteenth centuries.

CARTOGRAPHY

Little need be said of the cartography of antiquity,[163] for although medieval maps undoubtedly owe much to classical predecessors, none of the classical maps which were destined directly to influence the cartography of the Middle Ages have come down to us. Indeed we have good copies of only two. These are the maps of Ptolemy and the so-called Tabula Peutingeriana,[164] or Peutinger Table. Ptolemy’s maps exerted no influence whatever on the cartography of the age of the Crusades.[165]

The Tabula Peutingeriana is preserved in a manuscript of the twelfth century or earlier and probably was originally copied from a large chart showing the main routes and provinces of the Roman Empire. It is an extremely long and narrow affair in which the geography is woefully distorted. Though in itself hardly representative of the best in the Roman cartographer’s art, the original may have been compiled from a contemporary Roman map of the world and adapted through its long and narrow form to the especial purpose of illustrating itineraries. We know that maps of the world were officially drawn in imperial Rome and posted up for the benefit of the public: the one constructed by the order of Agrippa and Augustus in the Porticus Octaviae was the most famous;[166] and others are mentioned in literary sources.[167] Certain medieval maps of the world are possibly related to some of these Roman charts,[168] but unfortunately in the absence of the Roman maps themselves the exact relationships cannot satisfactorily be worked out.

Although the ancient astronomers knew a variety of projections for representing the heavens—stereographic, orthographic, and others[169]—these were not applied to maps of the earth until long after our period. Ptolemy describes several projections, among them the conic, which he may have used; but there is no question of any mathematical projections in the twelfth and thirteenth centuries, and none of the cartographers of that period took account of the fact that they were endeavoring to show a globe on a flat surface.

_THE EXPANSION OF REGIONAL KNOWLEDGE_

We have seen what the geographers of antiquity thought about the general distribution of land and water and about the physical processes of the earth’s surface. We now must study a subject which is less concerned with what they thought than with what they actually knew—however vague and inexact this knowledge was. Though the heritage of knowledge which antiquity left to the Middle Ages of the countries and regions of the _oikoumene_ was vast, much had been lost and much garbled in the process of transmission. Hence it would be beside the point to discuss the details of topographic information contained in the works of Strabo, Pliny, and Ptolemy; our aim is merely to indicate in a broad way the limits of the regional knowledge of the ancient world. This can best be done by sketching the various stages in which the horizon of geography was expanded until it reached the Shetlands and Scandinavia in the north, China in the east, and, perhaps, the Central African mountains in the south.

EXPANSION OF GREEK REGIONAL KNOWLEDGE

Homer’s geographical horizon was limited by the Mediterranean—one might almost say Aegean—shores; Italy, Sicily, and everything to the west was a realm of fable, and his acquaintance with the Black Sea coasts was little better. The colonizing movement of the eighth to the sixth centuries before Christ brought Greek settlers to these coasts; and through them there was gained some acquaintance with the country behind them, which found expression in the writings of Hecataeus at the close of the sixth century. With this writer ancient geography begins to assume its familiar classical form. He shows some slight knowledge of Central Asia beyond the Caspian Sea and is even aware of the existence of India—or at least of the northwestern portions of that peninsula. The great struggle with Persia brought the Greeks into much closer relations with Asia, and a corresponding increase in geographical knowledge ensued. This was summed up by Herodotus. Much of his geography is fabulous and legendary, but much of it is of surprising detail and accuracy. The voyage of Scylax of Caryanda from the Indus to the Persian Gulf had brought the Indian Ocean within Greek ken. Herodotus also describes the rivers of Scythia and of Central Asia and displays detailed familiarity with Egypt and northeastern Africa; he knew less of the West, although at about this same time the voyages of the Carthaginian Hanno in the Atlantic Ocean extended the horizon at least as far as the Canaries, which were destined to remain on the limits of the known world in that direction for many centuries to come. Shortly after Herodotus, Ctesias, who had lived seventeen years at the Persian court, wrote his _Persica_ and _Indica_, in which we find collected together many of the fabulous and marvelous tales of Oriental animals and monsters which were later to figure so strikingly in the _Historia naturalis_ of Pliny, in the medieval encyclopedias, and in the _Physiologus_, a collection of animal lore widely read in the Middle Ages. Further detail regarding the local features of Mesopotamia and Armenia was learned from the expedition of Cyrus and preserved for the future in Xenophon’s _Anabasis_. But the events which did most to expand the regional knowledge of the ancients were those connected with Alexander’s conquests and with the reigns of his successors. Alexander’s march in itself opened to Greek eyes wide territories that had been unknown before; it brought Greek armies and, after them, Greek merchants into the innermost heart of Asia; it established direct connections with India; rumors reached the companions of Alexander of an enormous island of Taprobane in the Southern Ocean, an island which we now recognize to be Ceylon. With the voyage of Nearchus came a better understanding of the Indian seas; and subsequently under Seleucus I (Nicator), Megasthenes, who was sent as ambassador to the court of an Indian potentate on the Ganges, gave a detailed description of the tribes and products of Hindustan, more extensive notes on Taprobane, and—unfortunately—a repetition of the fabulous legends of Ctesias. Patroclus, in command of the easternmost provinces of the kingdom of Antiochus I, provided some valuable statistical and geographical facts about the peoples of the Caspian region, although he was quoted as an authority for the belief that the Caspian communicates with the outer ocean and that it is an easy matter to sail thence to India.

GEOGRAPHY AT ALEXANDRIA

In addition to the reports of travelers and eyewitnesses, the establishment of Greek control over Egypt and the greater part of southwestern Asia led to a scientific awakening that centered in Alexandria. One of the greatest triumphs of Hellenistic science was the geographical and astronomical school that flourished at Alexandria under the Ptolemies. Eratosthenes and Hipparchus were undoubtedly the most famous representatives of this school, and in them we see the culmination of Greek scientific geography; for their work, all things considered, surpassed that of Claudius Ptolemy, and the work of no other man approached it. Though Eratosthenes’ researches were significant mainly in the field of mathematical geography, he made use of much of the regional knowledge which was available in the library at Alexandria and which he could gain from enterprising Greek traders, administrators, and soldiers who had actually visited the countries with which he deals in his treatises.

One striking result of this broadening of regional knowledge was the lesson it taught in regard to the countries south of the Tropic of Cancer. The progress of exploration in Upper Egypt and in India showed that these countries were not only habitable but thickly settled. Adherents of what we have called the Cratesian theory were obliged to acknowledge that the tropic could not be taken as the beginning of the burning zone. Eratosthenes pushed the limit of the _oikoumene_ as far south as latitude 11½° N.[170]

HELLENISTIC REGIONAL KNOWLEDGE

While Greek military enterprise had been opening up the Orient and exploratory enterprise penetrating the tropics, an important advance was made in the direction of the northwestern seas and the British Isles. The voyage of Pytheas of Marseilles, about 330 B. C., had brought within the scope of ancient knowledge Britain, Scandinavia, Thule, and the frozen ocean beyond. Thus, in the Hellenistic period the frontiers of knowledge included the Orkneys, Shetlands, Faroes—or whatever of the northern isles was meant by Thule—the Canaries, tropical Africa, and Ceylon. No further notable extension of these borders seems to have been made until the first century after Christ, except that vague rumors of a people called “Seres” and of the use of silk had crept into the Roman world in Virgil’s time. This may have indicated acquaintance with China, although Horace took the Seres to be a tribe of Central Asia.[171] The Scythian invasions which overwhelmed the Greek kingdom of Bactria and the conquest by the newly risen power of Parthia of the provinces of the Seleucids east of the Euphrates tended to cut all communication with the interior and farther parts of the Asiatic continent; but the Mithridatic wars, as described by Theophanes, familiarized the public with the local geography of Armenia, Pontus, and the Caucasus. Similarly Caesar’s campaigns in Gaul, Germany, and Britain opened Western Europe to the Roman world.

REGIONAL KNOWLEDGE OF MELA AND PLINY

The most complete and accurate summing up of the regional geography of the ancients was the _Geography_ of Strabo, written in Greek probably shortly before 17 A. D. But, as we have seen, this work was unknown to our period of the Middle Ages, when men had to rely on Latin writers like Pomponius Mela and Pliny, whose writings were of distinctly inferior quality and included a great deal of fabulous and worthless material. Devoid of that critical judgment which characterized Eratosthenes and Strabo, Mela and Pliny were content to bring together huge quantities of miscellaneous information, much of which was derived from antiquated Greek sources. Mela, for example, closely follows Herodotus’ description of the marvels of Asia, and Pliny retails many of the fanciful legends of Ctesias and Megasthenes. Pliny’s contributions to geography were somewhat more satisfactory than those of Mela; for he added some details about Asia that had not been mentioned before, especially in his description of Serica and of India and in his account of the monsoons. On the other hand Mela was the first writer to mention the Baltic Sea, or “Sinus Codanus,” which he described as a great gulf full of islands.

THE “PERIPLUS OF THE ERYTHRAEAN SEA”

Nearly contemporaneously with Pliny there came an advance in the knowledge of the Indian Ocean in the anonymous Greek _Periplus of the Erythraean Sea_, a manual for sailors and merchants. This is of interest because it gave indications of the existence of coasts and islands beyond India, the islands of Chryse, the land of the Seres, and, at the end of the earth to the east, a region of “Thin”—the first mention of the word “China” in the West unless we take into account the “Sinim” of Isaiah xlix, 12, which may or may not have referred to the great nation of the Far East.

At about the same time, as we have already seen, the upper reaches of the Nile, possibly as far as the great marshes of the White Nile in about latitude 9° N., were explored by the expedition described by Seneca and Pliny which Nero sent out to solve the age-long mystery’ of the sources of the river of Egypt.[172] Pliny accordingly placed the southern border of the _oikoumene_ some 7½° south of the position to which Eratosthenes had assigned it, or at about latitude 4° N.[173]

LIMITS OF ANCIENT REGIONAL KNOWLEDGE ON THE SOUTH AND EAST

Before the days of Marinus of Tyre and Ptolemy the limits of geographical knowledge were again much extended both southward and eastward. The Ptolemaic map depicts a wealth of detail in the interior of Africa, although we are unable to say with assurance what most of this detail represents in reality.[174] Ptolemy certainly had some knowledge of the great lakes and mountains of east-central Africa. The snow-covered mountains which he placed at the sources of the Nile may be associated with reports derived from the east coast of Africa, of Kenya, Kilimanjaro, or possibly the Ruwenzori range.[175] Farther to the west he describes a river, the Nigir, flowing from a region south of the country of the Garamantes (probably modern Fezzan) to the westward into a lake near the Atlantic. It seems altogether likely that by this river he meant the Niger. Ptolemy mentions two expeditions that had been made at an unknown period to the south from the land of the Garamantes, one under Septimius Flaccus, who arrived at the country of the Ethiopians after three months’ journey, and the other under Julius Maternus and the king of the Garamantes, a four months’ journey to a country called Agisymba, abounding in rhinoceroses. Ptolemy’s regional knowledge certainly extended as far south as the equator, and he was well aware of the fact that the equatorial zone is inhabited.

In the east, also, the Ptolemaic map reveals an advance in knowledge over its predecessors. Chryse appears as a peninsula, and other islands and coasts are shown that certainly indicate familiarity with the Malay Peninsula and China, possibly also with Borneo and Java. We shall find, however, that these valuable extensions of knowledge eastward and southward were universally lost sight of in the West in the Middle Ages and that cosmographers were united in placing India or Paradise as the farthest end of the world in the one direction and either the shores of the Ethiopian Ocean immediately beyond the Garamantes or the edge of the uninhabitable zone at the tropic or not far beyond it, as the extreme limit in the other.[176]