We’ve never escaped the influence of the Babylonians. That there are 60 seconds in a minute, 60 minutes in an hour, and 360 degrees in a full circle, are all echoes of the Babylonian preference for counting in base 60. An affinity for base 12 (inches in a foot, pence in an old British shilling) is also an offshoot, 12 being a factor of 60.
All this suggests that the Babylonians had a mathematics worth copying, which was why the Greeks did copy it and thereby rooted these number systems in Western tradition. The latest indication of Babylonian mathematical sophistication is the discovery that their astronomers knew that, in effect, the distance traveled by a moving object is equal to the area under the graph of velocity plotted against time. Previously it had been thought that this relationship wasn’t recognized until the fourteenth century in Europe. But since historian Mathieu Ossendrijver of the Humboldt University in Berlin found the calculation described in a series of clay tablets inscribed with cuneiform writing in Babylonia during the fourth to the first centuries B.C.E., where it was used to figure out the distance traveled across the sky by the planet Jupiter.
It’s a startling find. But media accounts of the work have exaggerated its significance for understanding what the Babylonians were up to when they did astronomy. Some have implied that the tablet shows the Babylonians “invented geometry,” or even that they invented calculus. The reports betray an urge to turn the Babylonians into the equivalent of modern-day astronomers in sandals and loin-cloths, diligently mapping the heavens in order to understand the cosmos.
This reception of Ossendrijver’s work shows that we still struggle to make sense of what “science” meant before the word, or even the concept, had been invented. On the one hand we are inclined to hype the past, eager to show how they already “knew” what we took to be more recent discoveries. On the other hand we patronize it, claiming (as physicist Steven Weinberg did in his 2015 book To Explain the World) that they’d have gotten a lot further quicker if they’d been able to abandon silly superstitions like astrology and magic.
Historians call this tendency to scrutinize and judge the past according to the perspective of the present “Whig history,” a term coined in 1931 by the historian Herbert Butterfield, who criticized the practice for ignoring what people in the past were actually interested in doing. According to Butterfield, by engaging in Whig history we filter and warp the thought of others to make it fit our own—as though the aim of the past was to create the present. Weinberg’s book, along with a re-analysis of the “scientific revolution” of the seventeenth century by historian David Wootton (The Invention of Science; 2015), has reignited the arguments about Whiggishness in the history of science. Is it right to seek presentiments of modern science in the works of the ancients, or should we judge their “science” on its own terms?
Babylonian astronomy is a great place to weigh up these arguments—because, perhaps more than in any other time and place in history, it shows us an example of what we must regard as astronomy (observing, mapping, and predicting the movements of the stars, planets, sun and moon) being put to a very different use from the one we’re used to. The “astronomers” of ancient Greece—scholars like Eratosthenes, Hipparcus, Ptolemy and Aristotle—were interested in trying to understand what the heavens looked like. They constructed a theoretical model of the cosmos in which the planets moved in circular orbits around the earth at its center, which was used almost without exception in the West until Copernicus’s heliocentric theory in the sixteenth century. The Greeks “look” to us like scientists, trying to understand the world around them.
The Babylonians were different. They inhabited the region called Mesopotamia between the Tigris and Euphrates rivers (present-day Iraq) in the second and first millennia B.C.E. Babylonian astronomers surveyed the skies carefully, keeping detailed records of the movements of the stars and planets. They recognized five planets (Mercury, Venus, Mars, Jupiter and Saturn), along with the sun and moon, and called them “wild sheep” because of their wandering paths over the fixed backdrop of the stars.
But these studies weren’t concerned with “understanding” the cosmos; they were conducted for astrology. The Babylonians believed that their gods transmitted messages about the future through the appearance of the celestial bodies: when planets rose over the horizon, what color they were, when they stood in certain arrangements or conjunctions, when eclipses happened, and so on. It was the task of scholarly diviners to interpret these messages, so that they could deliver sound advice to the king.
Reading these signs was complicated and subjective. Certain features were omens, considered to presage particular events. One document, for example, suggests that if the moon is still visible on the 30th day of the lunar cycle then destruction of Babylonia is on the cards, but if the moon is seen on the first day of the cycle then good luck will follow. Mars, meanwhile, was a harbinger of evil, whereas Jupiter brought peace and plenty. With all the different possible parameters, it was never easy to read the gods’ code. That was the diviners’ job, and it more closely resembles a legal process of weighing up precedents than a scientist’s aim of finding an objective truth that “explains” the observations.
While divination remained pretty much the sole motivation for astronomy for the duration of Babylonian civilization, the methods changed significantly from around the late seventh century B.C.E. It was then that the concept of a zodiac appeared: The sky was divided into 12 segments, identified with particular constellations (although the stars themselves rotate across the zodiacal divisions), which became one of the organizing principles for making predictions. This zodiac was inherited by the Greeks, along with the Babylonian techniques for using it to cast horoscopes—it’s the system still used for astrology today, when we speak of, say, “Jupiter in Aquarius.”
Even more significantly, the “new” Babylonian astronomy differed from the old in that it made predictions about how the heavens would look. The ancient Babylonians couldn’t fail to notice that many astronomical events recur periodically—for example, that there is a cycle of 223 months in the pattern of eclipses, or that Saturn rises in the same place in the sky every 59 years. Even for these things to become evident required careful observation and record keeping over generations.
These regularities were previously seen as quirks of the gods’ messaging system, but around the 7th century B.C.E. scholars began to appreciate that they could be used to predict how the night skies would look in the future. This might seem obvious now. But with so many variables to think about, some of which (like the color of the moon or brightness of the planets) weren’t really predictable, it wasn’t clear how much significance to give to periodic movements. It seems likely that the move towards predictive astronomy came not from any desire to understand the cosmos better or to explain what was seen in terms of some underlying model, but from royal demands for better forecasts. Faced with such a challenge, scholars vied with each other to develop predictive methods, which stimulated the increasing use of mathematics—like the recently discovered methods used to track Jupiter.
What resulted does look like science in some respects. For one thing, an astronomical prediction, unlike the older forecasts, can be falsified by observation. If you wrongly predicted the king’s health, you could say that you misread the signs (and woe betide you). But if you predict an eclipse that doesn’t happen, it’s your mathematical method that’s at fault. Mathematical astronomy is, like science, objective and value-free, operates with known rules, and depends on careful measurements and records of data.
That might leave Weinberg and like-minded supporters of Whiggish science history breathing a sigh of relief, but it doesn’t mean that the new Babylonian astronomy was a sort of proto-science. For one thing, the Babylonians, unlike the Greeks, seem to have had no concept of, or interest in, any mechanism that explained the celestial dance. They didn’t think in terms of planets making physical orbits, around the earth or sun or anything else. Sure, they would calculate how far Jupiter had “moved” in the sky. But this motion was more like that of the hands of a clock—as opposed to the gears—the new position signified a new meaning, but who cares about how the movement happens? That’s a matter for the gods.
Even eclipses weren’t pictured in terms of a physical conjunction of sun, moon and earth; if they were “explained” at all, it was in mythical terms, for example the god Sin (symbolized by the moon) becoming surrounded by demons. Greek astrology and later Western iterations, in contrast, depended increasingly on ideas about physical mechanisms by which the planets and stars might affect events on earth, for example because of “emanations” that the celestial bodies exerted just as the sun emanated heat and light.
One common responses to all this is to say that the Babylonians began to discover objective, “scientific” knowledge about the world by accident, for the wrong reasons: Their motives may have been misguided, but they got useful knowledge all the same. By the same token, it’s sometimes said, the alchemists discovered a lot of handy chemistry in their fool’s quest to make gold. But trying to sift the past for morsels that can be called precursors of science makes for bad history. Babylonian astronomy was not an “imperfect science” but a self-contained intellectual framework woven into the rest of their culture. Of course, no Babylonian scholar ever really foresaw the death of a king or victory in battle written in the stars. Yet Babylonian astrology wouldn’t have survived for over a millennium if it hadn’t in some sense “worked” in its own terms: if it hadn’t helped to order and stabilize society. And to the extent that it created viable mathematics and astronomy, this didn’t happen because the practitioners, like today’s scientists, were seeking some abstract truth about the world— it came about because of immediate practical and political concerns.
Does this mean that the minds of the Babylonians are a closed book, so different from ours in their worldview that we can’t meaningfully seek any continuity between them? I don’t think so. The one thing predictive Babylonian astronomy surely shares with modern science is a belief that the universe embodies and obeys some order knowable by human minds: Not everything happens through the immediate whims of the gods. And if that’s so, the gods themselves recede just a little further, and we trust a little more that, if we ask the universe questions, it will give us fathomable answers.