Chapter 4

IT HAS BEEN SAIDthat “in the general decline of learning that overtook Western Europe during the first Christian centuries, no science suffered a more complete eclipse than astrology.” To flourish, it had required the books, instruments, astronomical tables, and relevant knowledge that only an environment sympathetic to higher education could supply. The Dark Ages were conspicuously lacking in those cultural coordinates. That was in the West. In the East, in the Empire of the Byzantines, it continued as an object of study; and in the Arab world it was taken up and embraced. Although the Koran forbade the worship of the Sun and Moon, astronomy and astrology prospered, as did the other sciences and arts.

Meanwhile, in the Near and Middle East, Islam had emerged as the dominant faith. InA.D. 610, a forty-year-old merchant of Mecca named Muhammad had a vision in a cave above the city that convinced him that he had been chosen by God to be the unique Arab prophet of sacred truth. He made few converts at first, many foes, and after an attempt on his life he fled to Medina, where he established a theocratic city-state. He attracted an ever-larger group of adherents and began to extend his sway. Over the next few years, Muhammad fought several pitched battles with rivals and opponents, which he unexpectedly won—thereby gaining stature as well as ground—and before long, his missionaries began to fan out across the Arab world. As new disciples flocked to his standard, his religious army grew, and in 630 Mecca itself fell without a fight. That proved a herald of his incontestable power, and, in a remarkably short time, the tribes of Arabia were united under Islam and its creed. Part of that creed was conquest (in a parallel with the Christianity of the later Crusades), and just seven years after the death of Muhammad in 632, the Arab assault on North Africa began. Attacking simultaneously on several fronts, small bodies of mounted zealots ripped into the Byzantine Empire and from that point on the movement gathered tremendous force and speed. Palestine, Syria, Egypt, Cyprus, Tripoli, Carthage, and the whole of Persia fell in succession, and by 711 the entire coast of Africa, from Suez to the straits of Gibraltar, was under Islamic control. The Arabs then advanced into Spain, and pushed irresistibly northward into Provence. It wasn’t until the victory of Charles Martel at Poitiers in 732 that their progress in the West was checked. By then the Byzantine Empire had been drastically reduced, while the once tiny militaristic sect of Islam commanded tens of millions of subjects from Gibraltar to the Aral Sea.

The administration of the whole of this territory was centered at first in Syria, at Damascus. But power struggles soon emerged among rival clans. Not long after the conquest, the ruling dynasty, known as the Umayyads, was overthrown by the Abbasids, and a decision was taken to transfer the seat of government further to the east. In 762, Abu Jafar al-Mansur, the second caliph of the new dynastic house, traveled the length of the Tigris River looking for the ideal site. Eventually he settled on a little village on the west bank of the river where it was connected to the Euphrates by canals. The village was surrounded by palm trees, accessible from both rivers, as well as to caravans from Syria and Egypt; the Persian Gulf was a route to the Byzantine Empire and even China by the sea. Construction of the new capital then proceeded at breakneck speed. The caliph himself laid the first brick, and a huge labor force of 100,000 was drawn together from the cities of Mosul, Kufa, Wasit, and Basra, as well as from Syria, Persia, and other lands. Some of the bricks used were huge and weighed up to two hundred pounds. Within eight years, the round city, as it was called, was completed as a military stronghold, bounded by three concentric walls and surrounded with a moat. In the center stood the Golden Gate palace of the caliph surmounted by a great green dome and connected to the Great Mosque. Four main gates, set on a rectilinear axis, like the four points of a compass, opened out onto highways that connected the palace with the far-flung reaches of Arab rule.

Thus was Baghdad—known as “Dar es-Salaam,” the City of Peace—founded. It developed rapidly into a vast emporium of trade linking Asia and the Mediterranean, and by the reign of al-Mansur’s grandson, Harun ar-Rashid (786–809)—in English, Aaron the Just, the caliph of theArabian Nights —surpassed even Constantinople in prosperity and size. Its administration had managed to harness the Tigris and Euphrates rivers for the cultivation of grain, and a brilliant system of canals, dikes, and reservoirs drained the surrounding swamps. Immigrants of all kinds—Christians, Hindus, Persians, Zoroastrians, and so on—came from all over the Moslem world, and from lands as far away as India and Spain. For the most part, they were welcomed in an ecumenical spirit, and there was much to entice them to stay. There were many rich bazaars and covered shops along the embankments, where all sorts of artisans and craftsmen—marble workers from Antioch, papyrus makers from Cairo, potters from Basra, calligraphers from Peking—plied their trades. Food stalls sold lemon chicken, or “lamb cooked over a spit with cardamom, or small rolls dipped in honey, or flat slabs of pita bread smeared with fat.” There was a large sanitation department, many fountains and public baths, and (unlike the European towns and cities of the day) streets that were regularly washed free of refuse and swept clean. Most households had water supplied by aqueducts, and some had subterranean rooms cooled by screens of wet reeds. Marble steps led down to the water’s edge, where, along the wide-stretching quay, river craft of all kinds lay at anchor—from Chinese junks to Assyrian rafts resting on inflated skins. Thousands of gondolas, decked with little flags, also carried the people to and fro. On the outskirts of the city were numerous suburbs with parks, gardens, and villas, some adorned with varnished frescoes of lapis lazuli and vermilion, or faience panels and ceramic mural tiles. An immense square in front of the central palace was used for tournaments and races, military inspections and reviews.

A bustling city by day, the lamp-lit nights of Baghdad had attractions in abundance, too. There were cabarets and taverns, game rooms for backgammon and chess, shadow-theater productions, concerts in rooms cooled by punkahs, and acrobats to entertain strollers by the quays. On street corners, storytellers regaled occasional crowds with tales such as those that inspired theArabian Nights.

In those glory days of Baghdad’s ordered splendor, London and Paris were still grimy and chaotic little towns made up of a maze of twisting streets and lanes crammed with timbered or wattle-and-daub houses whitewashed with lime. Most of the dwellings were shabby, and a fifth of the populations lived and died in the streets. There was no real paving of any kind, and for drainage only a ditch in the middle of the road. That ditch was usually clogged with refuse—including the welter from slaughterhouses as well as human waste—and in wet weather the streets were almost marshes, awash in a depth of mud. Footpaths along the main streets were marked by posts and chains. There were some shops, of course, but most of the real commerce took place at trading stations (like the famed Six Dials in Southampton, England) where livestock and crafts were purchased or exchanged. In Paris, all that remained from its commercial development under the Romans were the vast catacombs under Montparnasse.

Yet just at this juncture the West began to recover a little of its former light and strength. This happened under Charlemagne, the eldest son of Pepin the Short, and the grandson of Charles Martel, who had checked the Saracen advance into Europe at Poitiers. Charlemagne was a king of the Franks. In 773, his authority had been confirmed in Rome by Pope Adrian I, and he subsequently enlarged his kingdom to include the Pyrenées, northern and central Italy, parts of Bavaria, and territory north of the Rhine. In 778, he crossed into Spain, seizing the area around Pamplona, Barcelona, and Navarre, then, after taking Pavia in Italy, assumed the iron crown of the Lombard kings. Over the next thirty years he also occupied Saxony, advanced west to Pomerania against the Avars and Slavs, and by 800 had consolidated all of the Germanic peoples of western continental Europe under his rule. That same year on Christmas Day he was crowned at Rome by Pope Leo III and the Holy Roman Empire was born.

As emperor of the West, Charlemagne made contact with ar-Rashid in Baghdad, and the two exchanged several embassies over the next ten years. A contemporary account of one of these missions was left to posterity by “Notker, the Stammerer,” a monk of St. Gall, whose somewhat naïve and tendentious narrative sought to exalt Charlemagne at ar-Rashid ’s expense. The Baghdad envoys, he tells us, arrived in the last week of Lent, 807, but Charlemagne delayed receiving them until Easter eve. He then donned himself in full royal attire—a brightly embroidered tunic fringed with silk and adorned with precious stones—which Notker assures us overawed the Arabs, for “he seemed to them so much more than any king or emperor they had ever seen.”

Charlemagne then gave them a tour of his palace complex, during which “the Arabs were not able to refrain from laughing aloud because of the greatness of their joy.” Compared to the imperial splendors of ar-Rashid’s Golden Gate Palace, with its great green dome, Charlemagne’s estate at Aachen or Aix-la-Chapelle—a site chosen for the therapeutic vapors of its warm sulphur springs—was rather modest, despite the marble columns and mosaics he had obtained for its adornment from Ravenna and Rome. (As for his country estate at Asnapium, which the Arab envoys may also have seen, it featured, according to one contemporary acccount, “a royal house built of stone in the very best manner, having three rooms.” No matter what those rooms might have looked like, that was not likely to overawe.)

Following Easter service on the following day, Charlemagne regaled the envoys at a banquet, but, according to Notker, they were so amazed at all they saw “that they rose from the table almost as hungry as when they sat down.” (In fact, they found the food repellent but were trying to be polite.) However, one evening during their stay they got soused on barley beer and indirectly betrayed what they thought of Charlemagne’s might. Notker reports it this way:

The envoys were more merry than usual, and jokingly said to him, who as always was calm and sober: “Emperor, your power is indeed great, yet it is much less than the report of it which is spread throughout the kingdoms of the East.” “Why do you say that, my children?” he replied. “How has that idea come into your head?” “All the peoples of the East fear you,” they replied, “much more than we do our own ruler, Haroun. As for the Macedonians and the Greeks, what can we say of them? They dread your overwhelming greatness more than they fear the waves of the Ionian Sea. The inhabitants of all the islands through which we passed on our journey were as ready and keen to obey you as if they had been brought up in your palace and loaded by you with immense favors. On the other hand, or so it seems to us, the nobles of your own lands have little respect for you, except when they are actually in your presence. For when we entered your domains and began to look for Aachen, and explained to the nobles we met that we were trying to find you, they gave us no help at all but sent us away.”

In other words, people a long way off may be impressed by rumors of your power, but up close it doesn’t seem to amount to much. Notker, however, missed the point and thought Charlemagne was being praised for the awe he inspired in distant lands.

Protocol was maintained, however, and handsome gifts exchanged. The Arabs had brought him various spices and unguents, brass candelabra, ivory chessmen, a colossal tent with many-colored curtains, and a water clock that marked the hours by dropping bronze balls into a bowl. As the balls dropped, mechanical knights or horsemen—one for each hour—emerged from behind little doors which shut neatly after them as they stepped forth. Notker also mentions a white elephant (an earlier gift), which had once belonged to an Indian raja and which was later immortalized in stone in the cathedral porch of Bale. Included, too, was a beautiful astrolabe, along with a number of books on astrology “which Charlemagne, Emperor of France and Germany, commanded to be translated into Latin from Arabic.” Thought Notker: “They seemed to have despoiled the East that they might offer all this to the West.” Charlemagne reciprocated as best he could with some embroidered cloaks from Frisia, a few Spanish horses, and some hunting dogs “specially chosen for their ferocity and skill.”

When the Arab envoys returned to Baghdad, ar-Rashid immediately put the dogs to the test. They were released to chase a wild lion, which they managed to corner, and this (Notker tells us) so impressed the caliph that he took their prowess as emblematic of Charlemagne’s superior might. As evidence, Notker cited a letter in which ar-Rashid (with perfectly ironic generosity) affected to mourn the fact that the Holy Land was too far away for Charlemagne himself to defend, and so offered to defend it in his name.

Had war ever erupted between the two, ar-Rashid would likely have prevailed. Like Charlemagne, he was a formidable warrior, and while still a young man had led an army of 100,000 against the Byzantines, then ruled by the Empress Irene. He had met and defeated the renowned general Nicetas, and marched thence to Chrysopolis (now Üsküdar) opposite Constantinople on the Asiatic coast. Having pitched his tents on the heights, he had threatened to sack the city if a large annual tribute were not agreed to at once. It was paid forthwith, and for several years thereafter received with great fanfare at Baghdad, where the occasion was marked by festive events and a parade. In 802, however, the Byzantine Emperor Nicephorus I had refused to oblige. His envoy brought a defiant message to Baghdad, and, threatening war, threw a bundle of swords at the caliph’s feet. Drawing his own sword, or scimitar, the caliph, according to legend, cut the Roman swords in two with a single stroke without even turning the edge of his blade. Then he had dictated a letter which said: “Harun-al-Rashid, Commander of the Faithful to Nicephorus, the Roman dog: I have read thy letter. Thou shalt not hear, thou shalt see my reply.” He set out at once with a large army, took and sacked the Byzantine city of Heraclea on the Black Sea, and soon forced Nicephorus to submit. After the latter then reneged, ar-Rashid met and defeated his army in Phrygia in Asia Minor, where the Byzantines lost forty thousand men.

BY THE EARLY9TH CENTURY,Baghdad had become the cultural and intellectual center of the Islamic world. Ar-Rashid had done much to bring this about, but it was under his son, Abu al-Abbas al-Ma’mun, that the great flowering of Arabic culture reached its height. He was responsible for the translation of hundreds of Greek works into Arabic, and founded the Academy of Wisdom in Baghdad, with a large library where scholars of all races and religions could mingle in fraternal pursuit.

In time, the complete medical and philosophical works of Galen, thePhysics of Aristotle, the Old Testament (from the Septuagint Greek), Plato, Hippocrates, Ptolemy, Dorotheus, Archimedes, Euclid, and others were all translated, as the liberal arts flourished along with scientific research. Advances were made in spherical astronomy, geometry, algebra, trigonometric functions, integral calculus, and a number of other fields. The Arabs discovered algebraic equations, invented the zero, introduced Arabic (really Hindu) numerals, created the decimal system, perfected the lunar calendar, and from Spain to Samarkand built new observatories that in the end enabled them to double the level of celestial observations that the Greeks had attained. Indeed, many of the names of prominent stars, such as Betelgeuse and Rigel, and astronomical terms like nadir, azimuth, and zenith, were coined by the Arabs at this time.

If the astrological ideas that had inspired Columbus were espoused by a French cardinal, they were Arab in derivation, and the great schools of Islam were their source. Such schools flourished in Cairo and Alexandria in Egypt, in Kairwan (one of the first Islamic centers to open its doors to Coptic Jews) south of Tunis, and in Cordova and Toledo in Spain. But their central home was Baghdad, and anyone who wants to know what astrology has meant to world history must become familiar with that 9th-century intellectual capital of the world, where all the astrological ideas of antiquity—Babylonian, Greek, Roman, Persian, and Egyptian—made their vibrant home. Under the caliphs of Islam’s golden age, innovations flowed: the Arabs invented the solar return as a predictive technique for natal astrology, the Aries Ingress for mundane forecasts (public events), and further developed the conjunction theory of the Persians. From 622 on, Islamic, Jewish, Persian, Greek, and Hindu scholars flourished together. What today is called “Arabic astrology” is really that body of astrological learning—heavily influenced and shaped by the Greeks—that was assembled by Arabs, Jews, and Persians from the 8th to the 12th century in Arab lands. In particular, great Arab astrologers such as Masha’allah, al-Kindi, al-Biruni, and Abu Ma shar progressively joined Greek to Arab learning as Greek works became more available for them to study and assess.

Born in Basra at the mouth of the Persian Gulf, Masha’allah (known also as Messahalla to the West) was an Arab Jew who had taken part in the astrological deliberations that had led to the founding of Baghdad on July 31, 762. One of his notable colleagues in that enterprise was the great engineer Ibrahim Fazari, who also constructed the first astrolabe in the Arab world. In the course of his career, Masha’allah wrote on solar returns, ingress charts, conjunctions, and elections, but was particularly interested in how astrology could be applied to history. According to the 9th-century Christian astrologer Ibn Hibinta, his work in that field included the expert analysis of charts for the rise of Islam, the advent of Christ (which indicated that “violence befalls him from his people”), and for Muhammad (whose tenth-house Moon spared him the fate of Christ). He also wrote a commentary on Ptolemy and an astrological textbook that became a touchstone for all such studies in the Arab world.

This is part of his valuable discourse on “reception,” which has to do with the affections of the planets (according to sign placement) and their inclination to act:

You have to know that reception is formed through the exaltations and the domiciles [signs], but either way, it is the same thing: for example, if any one of the seven planets is found in the exaltation of another or in its domicile, and the same thing if it unites with another by important aspects; or if they are both in one sign, and one of them is in the exaltation of the other in union with it, when it unites itself with it by body (conjunction). For example, Saturn in 20 degrees Aries and Mars in 15 degrees Aries; in this case, Mars unites with Saturn by body, and Mars receives Saturn in its domicile, but the latter is not in reception with Mars…Another example is of connection and reception: when Saturn was in 20 degrees Aries, and Mars in 10 degrees Capricorn, and none of the other planets is closer to Mars in union with Saturn, that is within a few degrees. If Mars is united with Saturn within a degree, in such case they are found to be in mutual reception by domicile, since Mars receives Saturn because it is in its domicile, and Saturn receives Mars because it is also in its domicile.

Also, for the same reason, the exaltation is like the domicile: but the exaltation is of greater importance in the kingdom; i.e. if the question is about the king [because] the lord of the exaltation is stronger than that of the domicile. Hence, when the Sun is in 10 degrees Aries and Mars in 10 degrees Capricorn, the Sun is united to Mars, and Mars receives the Sun because it is in its own domicile; but the Sun does not receive Mars because it is not in its domicile. Likewise, each of the other planets can be united to its companion by domicile or by exaltation, by important aspect, or by being in the same sign…

Meanwhile, the first of Baghdad’s astrological schools had been founded in 777 by the Jewish scholar Jacob ben Tarik. That school was successively headed by al-Kindi and Abu Ma shar. Al-Kindi was an Arab from Kufu and, like Masha’allah, was educated at Basra. Enamored of Aristotle, he was a prolific scholar of prodigious scope. Some two hundred works are attributed to him, on subjects ranging from magic, philosophy, and metaphysics to mathematics, meteorology, and optics. It was al-Kindi who translated the works of Aristotle into Arabic, and his work on great-conjunction theory contains the earliest description of the use of some ninety-seven “lots” or “parts,” which, like the Part of Fortune, are arithmetically derived points on the ecliptic endowed with special force. (Many of these so-called Arabic parts, as they came to be called, were largely Greek in origin; others represent an original Arab contribution to the art.)

Abu Ma shar (known also in the West as Albumasar) in turn became professor of astrology at Baghdad University during the caliphate of al-Ma’mun. He had begun his career as a student of the Hadith, or sayings and traditions of the Prophet Muhammad. However, in 825 he undertook to learn mathematics in all its forms, including astrology. He studied with al-Kindi and eventually acquired immense renown as the leading astrologer of the Islamic world. After moving to Baghdad from Balkh in Khorasan, he devoted himself to the study of Persian, Greek, and Syriac texts, his eclectic mind welding their astrological doctrines into a single system, as set forth in his principal workThe Great Introduction to the Science of Astrology, composed about 850. Some fifty other books are also ascribed to him—including works on great-conjunction theory and solar returns—and altogether (as befits the foremost student of al-Kindi) his work had an encyclopedic range. One of his lost books, called theBook of the Thousands, apparently contained an outline of world history. It was Abu Ma shar, not incidentally, who also arranged for the translation into Arabic of Ptolemy’s great treatise on astronomy, thereafter known by its Arabic title as theAlmagest.

By and large, his stature as “the teacher of the people of Islam concerning the influences of the stars” remained unchallenged during his lifetime, though his willingness to allow students to dabble in “heretical views” angered extremists, and in the caliphate of al-Musta in—a degenerate monarch—he was flogged for not always insisting on their strict adherence to the tenets of the faith.

One of his surviving works is a little treatise entitledThe Abbreviation of the Introduction to Astrology —the earliest such manual translated into Latin—and a good compendium of the principles of his art. That art was fastidious, as exemplified by his third chapter, where he enumerates and explains the twenty-five “conditions of the planets” that determine their health and strength. These are: domain, advance, retreat, conjunction, aspect, application, separation, void of course, wild, translation, collection, reflecting the light, prohibition, pushing nature, pushing power, pushing two natures, pushing counsel, returning, refranation, resistance, evasion, cutting the light, favor, recompense, and reception. Many of these are wholly unfamiliar to modern astrologers. For example, “pushing power” means that if one planet is in its own house or exaltation, or otherwise dignified by term or face, and applies to another planet, it pushes its own power onto it. “Refranation,” on the other hand, refers to a planet that begins to apply to or move toward another but then aborts the aspect it made by reversing course. These distinctions were not insignificant, and in some cases determined the judgment of the chart.

A number of anecdotes from Abu Ma shar’s life survive. For example, “Once with some travelers,” he reportedly told a pupil,

I went to Baghdad and stayed with a friend of mine who knew a little astrology. He asked me how the Moon would be the next day, and I said, “In quartile aspect with Mars.” He said, “Then you mustn’t leave tomorrow”; and I said to him, “I have no intention of departing on such a day. But the other travelers won’t heed my warning.” “Let’s test them,” he said. So I said to them, “Tomorrow is an unfavorable day. Bide your time a while, and I’ll even see to it that your animals are fed.” But they would not listen. The next morning, they prepared to depart. As they did so, I observed that the Ascendant was in Taurus, Mars close to the Ascendant, and the Moon in Leo in quartile aspect to Mars. I said to them, “For God’s sake don’t go at this hour,” but they laughed at me in scornful disbelief and set out. I turned to my friend and said, “I’m heartily sorry for these senseless men.” We passed the morning in a leisurely repast, and were still sipping our drinks when some of the company came staggering back in. It turned out they had fallen among thieves, lost all their goods, and some had been killed. Strangely enough, some of the survivors now blamed me—“These things happened,” they said, “because of your superstition”—and threatened to beat me to death. I escaped by the skin of my teeth. Then and there I swore I would never again discuss the science of astrology with such ignorant folk.

Most ancient astrologers of any standing tended to abide by that rule, mindful that their knowledge had a powerful and sacred cast. Those of note included Muhammad ibn Ahmad al-Biruni, Haly Rodoam, Haly Abenragel (sometimes called Albohazen), Alcabitius, and Abu Ali al-Khayyat. Abenragel was tutor to the crown prince of Tunisia in Kairwan, and wroteThe Distinguished Book on Horoscopes from the Constellations. Alcabitius, also known as al-Qabisi from his birthplace, Qabisa, a village near Mosul in Iraq, was a mid-10th-century court astronomer and astrologer in Aleppo, Syria, who wrote anIntroduction to the Art of Astrology, mostly devoted to natal charts. Al-Khayyat, for his part, had been a student of Masha’allah and among many other works wrote a little book,The Judgments of Nativities, with valuable sections on everything from how to determine from a birth chart whether the native will prosper to how one’s brothers will fare. This is how he begins his guide to “The Native’s Wealth and its Sources, and the Things Signified by the Second House”:

Look at the second house from the Ascendant, because if the fortunes [Jupiter and Venus] are in it or in aspect to it, and the evil [planets] are not, and do not aspect it, and its lord is in a good place in the circle and from the Sun, it signifies good fortune. But if these same dispose themselves in contrary fashion, it portends loss to the native in portions of his wealth. Again, if the lord of the second applies to the lord of the Ascendant, it signifies the acquisition of wealth without much work; but if, conversely, the lord of the Ascendant applies to the lord of the second house, hard work is shown.

More formidable still was al-Biruni, to whom few could compare. Born near Khiva in Khwarizm in 973, by the Aral Sea, he was already an accomplished astronomer and mathematician by his late teens, when he successfully computed the latitude of his hometown by observing the maximum altitude of the Sun. The great scientist Abu Nasr Mansur, who developed trigonometric functions, took him under his wing, and before long considered him his peer. When he was twenty-two, al-Biruni wrote a treatise on the making of maps in which he explained how to accurately project a hemisphere onto a plane, but his scholarly work was soon interrupted by the pervasive unrest that had begun to plague the Islamic world. In 994, he sought refuge in a town in Persia known as Rayy, not far from modern-day Tehran, where he met and assisted the astronomer al-Khujandi, who had established a hilltop observatory, furnished with a giant sextant, from which he calculated the obliquity of the ecliptic and solstitial transits of the Sun. Over the next decade, al-Biruni served as court astronomer and astrologer to a number of caliphs and sultans, determined the longitude of various cities by comparing data on eclipses drawn from several locales, wrote three books on astrology, two on history, and one each on astronomy, the decimal system, and the astrolabe. In 1022, the caliph he was then serving, Mahmud of Ghazni, invaded northern India and invited al-Biruni to come along. The campaign lasted for four years, as the Arab troops advanced to the Indian Ocean. During that period, al-Biruni took advantage of the circumstance to determine the latitudes of a dozen towns around the Punjab and the borders of Kashmir. In his exploration of the region, he also mastered Sanskrit; took copious notes on India’s culture, customs, science, geography, and history; and later incorporated it all into an immense book calledIndia, a work of inestimable value for a knowledge of the subcontinent at that time. In other notable works, he wrote on “shadows” in all their aspects, including “the history of the tangent and secant functions, applicable to the astrolabe”; the idea that acceleration is connected with nonuniform motion; the use of rectangular coordinates to define a point in three-dimensional space; irrational numbers; ratio theory; trisection of the angle; algebraic equations; time keeping; hydrostatics; the velocity of light; Siamese twins; even flower petals and the workings of natural springs and artesian wells. He also carried on a polemical correspondence with the great Arab scientist Ibn Sina (known as Avicenna to the West) about heat and light, philosophy, astronomy, and physics; and many centuries before the telescope would confirm it, described the Milky Way as a nebulous collection of innumerable stars. Avicenna today is better known in the West, because his encyclopedic compilations in science, medicine, and philosophy became primary sourcebooks of the Latin Middle Ages. But al-Biruni had the greater mind.

Not surprisingly, his magisterial textbookThe Book of Instruction in the Elements of the Art of Astrology —is meticulously put together and has a strongly scientific, or mathematical, cast. It includes not only detailed explanations of the fundamentals, but algebraic and geometric demonstrations of their character. Written in 1029, it is a veritable primer of 11th-century science, with sections on geometry, astronomy, geography, arithmetic, and chronology; on the use of the astrolabe for astronomical as well as astrological purposes; on how to determine the width of a river or the depth of a well; and so on. It was al-Biruni’s conviction that no one could call himself an astrologer without a thorough knowledge of such disciplines. His succinct discussion of the received tradition is also admirably clear. “There are certain signs,” he writes,

which are described as places of exaltations of the planets, like the thrones of kings and other high positions. In such signs, the exaltation is regarded as specially related to a certain degree, but there are many differences of opinion in this matter, some saying that it extends to some degree in front of or behind the degree in question, while others hold that it extends from the first point of the sign to that degree, and again others that it is present in the whole sign without any special degree. Below are the signs and degrees according to the Persians and the Greeks: Saturn, 21 degrees of Libra; Jupiter, 15 degrees of Cancer; Mars, 28 degrees of Capricorn; the Sun, 19 degrees of Aries; Venus, 27 degrees of Pisces; Mercury, 15 degrees of Virgo; the Moon, 3 degrees of Taurus; the Dragon’s Head, 3 degrees of Gemini; the Dragon’s Tail, 3 degrees of Sagittarius. The opposite signs and degrees are regarded as places of dejection for the planets, where they are said to be in their fall.

Here is his comment on how one aspect of the houses may be assessed:

Prosperity is associated with the cardines, as these indicate a happy mean; adversity with the cadent houses, which point to destructiveness and excess. Being in those houses which are succedent to the angles is beyond the half-way line to prosperity, for they are the paths leading there from adversity. But this prosperity and adversity are not all alike, just as the cardines are not alike but are higher and lower in glory and dignity. And indeed the cadent houses are not alike in their destructive influences, because although the 3rd and 9th houses are cadent, the 6th and 12th are not only cadent but also inconjunct to the horoscope.

EVERYTHING IS BOUNDto Heaven’s wheel. Baghdad had been founded at a time deemed propitious by the ruling caliph, al-Mansur. His court astrologer, a Persian by the name of Naubakt, cast for the appropriate day and hour, and then consulted with his assistant, Masha’allah, who selected the early afternoon (2:40P.M. local time, to be exact) of July 31, 762, to lay the foundation stone. Jupiter at the time was rising and exactly conjunct the ascendant, which happened to be in Sagittarius, its own sign. The Sun, in trine to Jupiter, was then in its own sign, Leo, in the ninth house, in a sextile to Mars in the seventh, even as it moved away from a square to Saturn in the sixth. This augured well for Baghdad’s early glory as the seat of learning throughout the Arab world. But seldom a chart for good or ill without its obverse side. It so happened, in this instance, that Jupiter, on the ascendant, was directly opposed to Mars in the House of Open Enemies, indicating that it was Baghdad’s fate to flourish ( Jupiter trine Sun) in the field of higher learning, even as it was doomed to be undone by war.

By then, the Abbasid dynasty had gone the way of palace revolutions, the death of the great al-Ma’mun seeming to presage its course. The story is told that during his last campaign against the Byzantines he came to the River Qushairah in Asia Minor, and camped on its banks. Charmed by the clarity and purity of the stream, and by the beauty of the countryside around, he decided to pause a while to recoup his strength. So clear was the water that the inscription on a coin lying at the bottom could be read. But it was also extremely cold. One day, as a fish flashed before him “like an ingot of silver,” he was inadvertently splashed by an attendant trying to catch it and caught a chill. His aides wrapped him in blankets, but he soon became delirious and fell into a deep sleep. When he awoke, he asked the name of the place where he was. He was told, “Qushairah,” meaning in Persian “Stretch out thy feet.” He then asked for its name in Arabic and was told “Rakkah.” He sat up with a start. An astrologer in his youth had predicted that he would die in a place of that name. All along, he had thought it referred to the city of Rakkah in Syria, where he had always declined to go. Now he knew his fate. As night fell, he asked to be carried outside. He surveyed the long lines of his encampment and the light of the torches and campfires that twinkled into the distance as far as the eye could see. “O thou whose reign will never end,” he cried out sadly, “have mercy on him whose reign ends now.”

Of the eight succeeding caliphs, two were assassinated and two others died in exile in disgrace. Eventually, the center of Arab culture shifted from Baghdad to Cairo, under a different dynasty, and to Cordoba and Toledo in Spain.

Baghdad’s horoscope played itself out. In 1258, the city was sacked by the Mongols under Hulagu Khan, the grandson of Genghis Khan, and its great library burned to the ground. Scholars, civic leaders, and a large proportion of its inhabitants were slaughtered and a mountain made of their skulls. The caliph al-Musta sim—the last of the Abbasids—deluded himself into surrendering upon the promise that his life would be spared, but once in Mongol custody was “beaten to death in a sack.” In 1401, the city was sacked again and ravaged by the Mongol Tamerlane. These devastating onslaughts were naturally followed by social disintegration and political disarray. Thereafter, in the 15th, 16th, and 17th centuries Baghdad was repeatedly riven by factional violence, and fought over by the Persians and Ottoman Turks. The Ottomans seized it in 1638, but by then it was not much of a prize. It had lost its commercial importance, while its once-extensive irrigation system had fallen into disrepair. Tribal-based pastoral nomads now drifted in to occupy the ruins. But that was not the end of it, of course. The British occupied Iraq during World War I, were driven out by the Turks, only to return and capture Baghdad in 1917. Under their aegis, modern Iraq was created as an independent state. It, too, has had its once and future trials. But that is another tale.