The Chaldeans

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In the marsh country at the bottom of Mesopotamia, where the Tigris and the Euphrates lose themselves in reed beds and standing water before reaching the Persian Gulf, the Assyrians of the early ninth century BCE began to record the names of tribes they could neither tax nor easily subdue. They called them the Kaldu. These were the people the Greeks would later call Chaldaioi and the Romans Chaldaei — and by the time those Greek and Latin words were in common use, they had stopped meaning a people at all. A Chaldaeus was a man who read the stars. The marsh tribes had vanished into the general population of Babylonia centuries before, but their name had become, across the whole Mediterranean and Near Eastern world, the standard term for an astrologer and a master of the heavens. Three things have to be held apart to follow this: the people, the byword they became, and a Greek scripture of the second century CE that borrowed their prestige and has nothing to do with either.

Genealogy: the marsh tribes and the throne of Babylon

The Chaldeans were West Semitic tribes settled in the far south of Babylonia, in the alluvial land between the Arabian desert and the lower Euphrates. They are first attested in Assyrian texts of the early ninth century BCE, organized into several large tribal houses — the Bit-Dakkuri, the Bit-Amukkani, the Bit-Yakin — each named, in the Mesopotamian fashion, after an eponymous ancestor. They were not the original inhabitants of the region; the great old cities of the south — Ur, Uruk, Eridu — were Sumerian foundations of immense antiquity, and the Chaldeans settled among them as latecomers. Within a few generations of their first appearance in the record they had begun to assimilate, adopting Babylonian names, the Babylonian gods, and the long-established culture of Mesopotamia. By the middle of the eighth century BCE, as the Iranica synthesis of the Kaldu records, the Chaldeans had largely lost any distinct ethnic and political identity and had become simply one element among the mixed population of Babylonia.

What they retained was a memory of leadership. Through the eighth and seventh centuries the Chaldean tribal chiefs were the most persistent native rivals of Assyrian domination in the south, repeatedly seizing the throne of Babylon and as repeatedly being driven from it by the Assyrian kings. The most famous of these struggles attached to Marduk-apla-iddina II — the Merodach-baladan of the Hebrew Bible — chief of the Bit-Yakin, who held Babylon against Sargon II and Sennacherib and became, in the Assyrian record, the very type of the troublesome southerner. For most of two centuries the Chaldeans were a problem to be managed, not a power in their own right.

That changed in 626 BCE. In the long collapse that followed the death of the last great Assyrian king, a general named Nabopolassar — identified by many historians as a Chaldean, though the sources leave his exact origin open — took the throne of Babylon and founded the dynasty that the ancient world, and modern scholarship after it, would call Chaldean or Neo-Babylonian. Allied with the Medes, Nabopolassar turned on the Assyrian empire that had ruled the region for three centuries and broke it: Nineveh fell in 612 BCE, and the last Assyrian resistance was extinguished by 609. The wreck of the greatest power the Near East had yet seen passed into the hands of the marsh-country dynasty.

His son was Nebuchadnezzar II, who ruled from his father’s death in 605 to his own in 562 BCE — forty-three years, the longest reign of the dynasty. Under him the Chaldean kingdom reached the height that fixed it forever in memory. He destroyed the kingdom of Judah, took Jerusalem, burned its temple, and carried its people into the Babylonian exile, the event that runs through the Hebrew Bible and made the name of Babylon a permanent symbol of overweening power and captivity. And he rebuilt Babylon itself into the most splendid city of the age — the great processional way, the blue-glazed Ishtar Gate, the ziggurat the Bible remembered as the Tower of Babel, and the terraced gardens that classical tradition would number among the wonders of the world.

A nineteenth-century imagining of the Hanging Gardens, the terraced wonder ancient tradition assigned to Nebuchadnezzar’s Babylon. — Unknown artist, c. 1850, via Wikimedia Commons (public domain).

The dynasty did not long survive its great king. After a sequence of short reigns the throne passed to Nabonidus, a usurper of non-Chaldean origin whose devotion to the moon-god Sin of Harran estranged him from the Marduk priesthood of Babylon. In 539 BCE Cyrus the Great of the Achaemenid empire marched on Babylonia, and the city opened to him with little resistance. The kingdom of the Chaldeans ended after eighty-seven years. The name did not.

Teaching and significance: the writing of heaven

The thing that made “Chaldean” a word for star-reader was older than the dynasty and outlasted it by two thousand years. It was the Babylonian science of the sky.

Mesopotamian celestial divination is the longest continuous observational tradition in the history of the world, running from Old Babylonian roots through the Persian and Greek periods over more than a millennium of records. Its flagship was a canonical compendium called the Enuma Anu Enlil — “When the gods Anu and Enlil” — a series of some seventy tablets containing thousands of conditional omens, each built on the same grammar: if a given thing happens in the sky, then a given thing will follow on earth. If the moon was eclipsed in a certain month and watch, the king of a named land would die; if Venus appeared at a certain time, the harvest would prosper or fail. The phenomena watched were lunar and solar eclipses, the haloes of the moon, the risings and stations of the five visible planets, the heliacal appearances of fixed stars. This was not, in its own terms, prediction of the modern kind. It was reading. The sky was a script.

The Assyriologist Francesca Rochberg has drawn out the Babylonian phrase that captures this most exactly: shitir shame, “the writing of heaven.” Temples built to be beautiful were said to be made fair “like the writing of the firmament”; the stars were a divine inscription, and the celestial scholars were its trained readers. Within the divinatory establishment that surrounded the Enuma Anu Enlil there were recognized specialisms — the scribe of the celestial omen-series, the diviner who read the entrails of sacrificed animals, the exorcist who performed the apotropaic rituals that could turn aside a threatened evil. The famous letters of the Neo-Assyrian court preserve these scholars at work, writing to the king to report an eclipse and to recommend the rite that would answer it.

A tablet of the MUL.APIN series, the Babylonian compendium of stars, constellations, and the risings of the planets. — British Museum, via Wikimedia Commons (CC BY-SA 4.0).

For most of its history this was a science of the state. The omens concerned the king, the dynasty, the land, the harvest, the war — public fate, not private. The decisive turn came late, in the Persian period, and it is the Babylonian contribution that the Western world inherited most directly. Two innovations belong here. The first is the zodiac. In the second half of the fifth century BCE, Babylonian astronomers divided the band of sky through which the sun, moon, and planets move into twelve equal sections of thirty degrees each, named for the constellations that lay along them — the mathematical frame of Aries, Taurus, Gemini, and the rest, the scheme that still organizes a horoscope. The earlier star-lists, like the MUL.APIN compendium, had charted a “path of the moon” through some eighteen constellations; the late zodiac reduced this to a clean arithmetic of twelve equal signs that made planetary positions easy to record and to compute.

The second innovation followed from the first. Once the sky could be measured in degrees of the zodiac, the positions of the planets at any chosen moment could be written down — including the moment of a birth. The oldest known horoscope is a small cuneiform tablet dated to 29 April 410 BCE, on which a scribe recorded where the sun, the moon, and the five planets stood on the day a particular child was born. With it, the science of the sky crossed from the fate of kingdoms to the fate of persons. This is the true root of horoscopic astrology: the casting of a nativity from the heavens of the hour of birth. The full Greek apparatus — the rising sign, the twelve houses, the elaborate doctrine of aspects, the chart as a diagram — would be a later, Hellenistic creation. But the zodiac and the nativity, the indispensable foundations, were Babylonian.

One Chaldean order in particular has outlived everything else. The Babylonian astronomers ranged the seven moving bodies of the sky by their apparent speed, slowest to fastest: Saturn, Jupiter, Mars, the Sun, Venus, Mercury, the Moon. From a vantage at the center of the cosmos this was also the order of their distance, the nested spheres from the most remote planet inward to the nearest. In the Hellenistic period this “Chaldean order” was used to assign a ruling planet to each hour of the day and night in unbroken rotation; and when the planet ruling the first hour of each day was made to name that day, the sequence that fell out — Saturn, Sun, Moon, Mars, Mercury, Jupiter, Venus — became the planetary week. It survives, scrambled through Latin and the Germanic gods, in the names of the days still in use. Saturday, Sunday, and Monday keep the planets undisguised.

Reception: the byword, the book, and the Oracles

The afterlife of the Chaldeans is a study in how a name detaches from a people. By the late Hellenistic and Roman periods, “Chaldean” in Greek and Latin meant an astrologer, with no necessary reference to Babylonia at all. The historian Diodorus Siculus, writing in the first century BCE, described the Chaldeans as the priestly order of the Babylonians, devoted from birth to the study of the heavens, and held to be — by long observation of the stars — the most skilled of all peoples in foretelling the future. He set them deliberately beside the priests of Egypt: a hereditary caste of sky-watchers, the ancient world’s image of patient astral wisdom.

That image had a sharp double edge. Rome consulted the Chaldeans and Rome expelled them. The earliest recorded expulsion of astrologers from the city, in 139 BCE, drove out “the Chaldaeans” — described by the later epitomist as men who profited from the credulity of citizens by claiming to read fate in the stars. Cicero, in his treatise On Divination, noted dryly that the Chaldaeans took their name not from any art but from their nation, and then demolished their predictions: he had watched astrologers assure Pompey, Crassus, and Caesar of long lives and peaceful deaths at home, and marveled that anyone still trusted a craft so regularly contradicted by events. The Chaldean was at once the sage of the deepest antiquity and the street fraud worth banishing — and the ancient world held both of these at the same time, with no apparent strain.

The Ishtar Gate, glazed in lapis-blue brick for Nebuchadnezzar’s Babylon, reconstructed in Berlin. — Photograph by Rictor Norton, 2006, via Wikimedia Commons (CC BY 2.0).

The transmission of genuine Babylonian learning into Greek is associated above all with one figure. Berossus — in Akkadian Bel-reushu, a priest of Bel-Marduk at the Esagila temple — wrote a history of his country in Greek, the Babyloniaka, in three books, around 290 BCE, dedicated to the Seleucid king Antiochus I Soter. Its first book set out Babylonian cosmogony and the Chaldean science of the heavens for a Greek-reading audience; the work survived only in fragments quoted by later compilers, but it stands as the moment a Babylonian priest carried his tradition’s lore across the language barrier. Later tradition placed Berossus on the Greek island of Kos teaching Babylonian astronomy, though the evidence for any “school” there is thin and depends on much later anecdote.

The Hebrew Bible preserves a different reception, and preserves the ambiguity in miniature. In Genesis the patriarch Abraham comes out of “Ur of the Chaldees” — Ur Kasdim — an anachronistic phrase that retrojects the later population name onto the ancient Sumerian city. In the Book of Daniel, set at the court of Nebuchadnezzar, the word Kasdim carries both meanings at once: sometimes the Chaldeans are the people and the kingdom, and sometimes they are precisely a class of court diviners and wise men, the king’s astrologers and dream-readers, ranked among his magicians and enchanters. The same scriptural book that names the Chaldean kingdom uses “Chaldean” as a profession — the two senses already fused in the text.

Then there is the trap. In the second century CE there appeared a body of Greek hexameter verse that tradition ascribed to a theurgist named Julian, and that the later Neoplatonists — Iamblichus, Proclus, and their successors — treated as revealed scripture: the Chaldean Oracles. These are “Chaldean” only in their self-presentation. They are a product of Middle Platonist and theurgic religiosity, framed in the prestige-vocabulary of ancient Eastern wisdom, and they have essentially nothing to do with the cuneiform astral science of Babylonia. The name was a borrowed authority, exactly as “Chaldean” had become a borrowed title for any practitioner of star-wisdom. A responsible account of the Chaldeans keeps the Oracles in their own compartment: a distinct text that traded on the reputation, not a continuation of the tradition.

That reputation proved nearly indestructible. Babylonian astral material — the zodiac, the planetary exaltations, the arithmetic schemes for computing positions — passed into Greek astrology, and from there into the Arabic and Persian and the medieval Latin traditions, carrying the “Chaldean” label the whole way. The astral lore attributed to ancient Babylon would resurface again and again: in the pseudo-Babylonian Nabataean writings cherished by later occultism, in the star-religion of the Sabians of Harran, and in the long Western dream of a primordial wisdom handed down from the first sky-watchers. The decipherment of cuneiform in the nineteenth century at last recovered the actual record beneath the legend — the real omen-tablets, the real horoscopes, the real arithmetic — and showed how much of the legend was, for once, founded on something. The marsh tribes of the deep south were gone past recovery, their blood long dissolved into Babylonia and Babylonia long dissolved into Persia. Their name, attached to the oldest reading of the stars, had outrun the empire, the language, and the people who first bore it.

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