The Metaphysical World of Isaac Newton

by John Chambers

  Scaliger ransacked the great libraries of Europe and the Middle East and managed to come up with fifty ancient calendars. He harmonized them to create a single, global chronology putting the Greeks, the Romans, the Jews, the Persians, the Babylonians, the Assyrians, the Egyptians, the Ethiopians, and forty-two other cultures, all together on the same timescale. (The previous record was a matchup of five cultures.)

  When Scaliger was still a schoolboy, Copernicus’s precise calculations of the movements of the planets and their moons, upon which the astronomer based his paradigm-smashing demonstration that the solar system was heliocentric, were finally published. Astronomers could now calculate with great accuracy the position in the sky of the moons and planets the year before, a century before—millennia before—and in so doing pin down many a date in ancient history.

  Scaliger led this field. Early on, he worked out an accurate date for the Battle of Marathon, a pivotal event in the first Greek-Persian War, changing that date from 776 to 491 BC. Today, historians put it in September 490 BC.

  In his History of the Peloponnesian War, the great Greek historian Thucydides (460–396 BC) links three eclipses of the moon to three specific events in the twenty-seven-year-long conflict pitting Athens and its allies against Sparta and its allies. Scaliger used Copernicus’s tables to determine that the eclipses took place in 431 BC, 424 BC, and 413 BC. Modern-day historians date the Peloponnesian War at 431–404 BC.*45

  Scaliger blazed a trail that more and more European natural philosophers followed. Some of their projects seem whimsical to us today. The Polish astronomer Hevelius (1611–87) calculated just where the sun stood in the sky above the Garden of Eden on the first day of Creation. Edmund Halley (1665–1742) used his consummate mathematical and astronomical skills to determine exactly in what place and on what day Julius Caesar first invaded in Britain.

  Isaac Newton quickly added this brilliant new tool to the repertory of techniques he was using to date the ancient world. He located a second-century AD document quoting an earlier source to the effect that, in the fourth year of the 202nd Greek Olympiad, in Bythnia (now northwest Asian Turkey), an earthquake and a solar eclipse had occurred at exactly the same time. Newton decided these concurrent happenings were the literally earthshaking events accompanying Christ’s crucifixion and death on Golgotha, when “the veil of the temple was rent in the awful darkness that followed; when the rock of Golgotha was split apart by an earthquake; when the artillery of heaven thundered, and in the baleful glare of the lightnings the shrouded dead flitted about the streets of Jerusalem.”6

  Newton determined that this fourth year of the 202nd Olympiad was 34 BC and declared that this was the year of Christ’s death. The mathematician met with some objections from his colleagues, who reminded him that a solar eclipse lasts no more than six minutes while the darkness over Golgotha lasted nearly three hours. Superbly confident as always, Newton, felt no need to defend his conclusions.

  But even while he was coming up with this audacious calculation concerning the birth of Christ, Newton’s mind was already roaming restlessly backward in time to the expedition of the Argonauts. As has been said, he had concluded that Chiron had given Jason a newly minted star globe, and he was beginning to ponder the possibility of using a particular astronomical phenomenon to read the delineations on that star globe and figure out when Jason and his crew of fifty heroes had set sail.

  This particular astronomical phenomenon had been known to the ancient Chaldeans. It had been rediscovered by the greatest of ancient Greek astronomers, Hipparchus, in the second century BC. Newton himself had plotted its final decimal point, giving us the figure that we use today.

  It was called the precession of the equinoxes. Here is Isaac Asimov’s description of that phenomenon:

  About 150 BC, the Greek astronomer Hipparchus noticed an odd thing in connection with the sun’s motion against the stars. Twice a year, it seems, the sun crosses the celestial equator and shines directly above the earth’s equator. These moments are called the equinoxes. Hipparchus compared astronomical records made over hundreds of years, first by Babylonian astronomers, then by Greek astronomers. In doing so he found that the sun slowly changed position against the stars at the time of the equinoxes. Each year the sun crossed the celestial equator at a point a little farther to the east than it had the year before. The east is the direction of morning, so that the time of equinox, as measured by the stars, is a little earlier each time. Each equinox precedes (“goes before”) the one before. . . . For this reason, the shift is called the precession of the equinoxes. . . . Hipparchus decided that this shift could be most easily explained by supposing that the position of the north celestial pole was changing. If that were so, the whole sky would seem to shift in a single piece, carrying the stars (but not the sun, moon or planets) with it.

  As the earth turned, its axis moved in a slow circle. As it moved, it kept pointing to different parts of the sky, so that the north celestial pole moved as well.7

  In other words, the plane of the terrestrial equator is inclined to the Earth’s orbit at approximately 23½ degrees, and it is this inclination that accounts for the existence of the equinoxes and solstices. As the Earth moves in its orbit, and rotates to give what we call day and night, its axis also performs a slow gyrating motion with a period of 25,800 years. This means that over a period of 25,800 years the location of the equinoctial and solstitial lines, or colures, changes in relation to the fixed stars. It is a very slow change. The colures inch their way across the sky, returning to their starting point 25,800 years later.

  This tiny, continuous, observed change of place of the constellations is distinct enough that we can say each night sky has its own fingerprint. Since it takes the equinoxes 25,800 years to process through a full cycle, the sun passes through a different sign of the zodiac every 2,156 years. In the time of Hipparchus (ca. 190–120 BC), the sun rose and set in the sign of the Ram; over the past two thousand years it has been passing through the sign of Pisces; and, as all New Agers know, it has passed into the sign of Aquarius.

  The change in the sky’s fingerprint is virtually imperceptible from one night to the next. But it is visible over the seventy-two-year life span of a man or woman; in this time the constellations move en bloc one degree through the sky. (Imagine yourself standing in a field at night and turning in a full circle until you’ve scanned the entire horizon. You’ve moved through three hundred and sixty degrees.)

  But you had to have an actual star globe, or a star map, delineated not only with the stars of the night sky but also with the colures, or equinoctial and solstitial lines, to identify a particular year using the phenomenon of the precession of the equinoxes. And if Isaac Newton actually had such a star globe, however did he obtain it?

  To get an answer to that question, we first have to go to the palace of King Antigonus Gonatas of Macedonia, in Pella, on a day in the summer of 276 BC.

  Antigonus Gonatas, having summoned the renowned poet Aratus into his royal presence, was finding it difficult to speak to this physician-poet who seemed to hold him in contempt. Though fearless on the battlefield, Antigonus Gonatas was tongue-tied in the face of genius. Suddenly Aratus bowed politely in his direction. Antigonus Gonatas, finding his voice at last, told the poet he wanted him to write a Homeric poem that combined Zeus, the stars, and the weather.

  This would be an epic poem intended to protect the people of Macedonia from disaster. For two years, Antigonus Gonatas’s subjects had been suffering from storms, drought, crop failure, shipwreck, and starvation. The king wasn’t without humane instincts, and certainly not without the desire to remain in power. But how could he retain the support of his people in the face of these calamities?

  Antigonus Gonatas, and Aratus—and indeed most of the people living in Macedonia and Greece in the third century BC—believed that Zeus had created the night sky for one purpose only: to provide mankind with a gigantic clock and weather channel enabling us to tell the time,
predict the weather, and know when to reap and sow.

  The god had supplemented his meteorological night sky with quirks of animal behavior to further signal weather changes, as in, “And it is no sign of good weather when goats are busy about the prickly evergreen oak, or sows go frantic with the blown straw.”8

  In the ninth century BC, the poet Hesiod in his Works and Days had given the ancient world a quasi almanac deciphering the seasonal changes that Zeus set forth in the sky with the rising and setting of stars and the passage of mists that meaningfully riffled our view of the constellations.

  Other poem-almanacs appeared, such as the recent one by the poet Theophrastus. But, as mankind’s needs grew, more celestial devices were needed to successfully interpret those heavens. This was a problem that Gonatas hoped to address, by having the very renowned poet—and his subject to boot—Aratus update with an almanac written with a certain Homeric verve.

  Something happened that must have been coincidence but was surely a gift from the gods. It had emboldened the king to summon Aratus to help address the project. What happened was that, the week before, Antigonus Gonatas’s old and wizened royal astrologer, with whom the king had been discussing his project, had slipped into his hand a yellowed book at least as old and wizened as the royal astrologer himself.

  “This book,” the astrologer had intoned, “is a hundred years old! It was written by the great astronomer Eudoxus,” and the astrologer showed the king some of the pages. “It is a most exact and mathematical description of the fifty-five star families of the night sky. It is appropriate for your new project.”

  Antigonus Gonatas was about to take this under advisement when the old astrologer gripped him by the arm and, leaning forward, whispered urgently: “There is something divine in this book! It is said that Eudoxus copied these star families from a most ancient primitive sphere, a star globe so ancient as to have been furnished by Zeus himself. A star globe that embodies the graciousness of the stars.”

  The king took the book—it was titled Phaenomena (Phenomena, or Visible Signs)—and strode away. Antigonus Gonatas considered himself an expert on astronomy and, more importantly, a pious man. He knew about this Eudoxus. He knew he had been the greatest mathematician of his time after Archimedes. He also knew that Eudoxus had preached that pleasure was the highest good, that he had written a piece of mockery, Dialogue of Dogs, and that he loved to make fun of the philosopher Plato, sometimes even to his face. Could reworking the work of such a man possibly be a good thing? The king was inclined to dismiss this Phaenomena.

  But, over the next week, as Antigonus was daily shown evidence of the mounting plight of his subjects, he decided there was little time to lose and that he must use the book of that impious astronomer. So he summoned Aratus (who was living in his palace) and made the request to him that has been noted above.

  Aratus hesitated—which was, of course, futile, because Antigonus was the king. But just as Aratus was hesitating, the Stoic philosopher Persaeus, who was a permanent resident at Antigonus Gonatus’s court, suddenly appeared at the king’s elbow and admonished Aratus (apparently the philosopher was also in on this project too) to be sure and present Zeus in his new almanac as, not the stingy god of the proto-Stoicism of Hesiod, a god not able to offer mankind a way out of his ceaseless toil, but the full-blown Stoic god of Theophrastus, a kinder, gentler Zeus.

  So Aratus—who would stick mainly with Hesiod’s Works and Days as a structural model but would adopt the Theophrastian spirit—went off and wrote his poem.

  We know very little about Aratus (ca. 315–245 BC). It’s generally agreed that he was born in Soli, Cicilia, and went to Athens to study with the Stoic philosophers, particularly Zeno. He was probably sixty, and a poet of renown, when Antigonus Gonatus summoned him to his palace in Pella.

  It took Aratus two years to write his book, which he called the Phaenomena after Eudoxus’s learned tome. It was published in Athens. We don’t know what success Aratus’s poem had among the farmers, fishermen, and sailors of Macedonia, or even if it helped at all. We do know that it became an instant hit among the upper classes of Athens. If there had been a New York Times bestseller list in that great Greek city-state in 276 BC, this new Visible Signs would have gone straight to the top.

  Aratus’s Phaenomena is a combination Astronomy for Idiots, pint-size Homeric epic, and Farmers’ Almanac (two thousand years before Ben Franklin’s Poor Richard’s Almanac). Perhaps part of its charm came from the fact that it made it easy for the elite aristocracy of Athens to learn about the stars. And it contained a powerful dose of the Stoicism then popular (or feigned thus) among the elite of ancient Greece and Macedonia. Most of all, perhaps, it caught the powerful if subtle cadence of Homer in a manner that was universally appealing. Soon blue and golden paintings of the forty-seven stellar families of Aratus’s Phaenomena (he had left out eight of Eudoxus’s) were emblazoning the concave ceilings of the mansions of the rich and famous in Athens; the domiciles of the upper classes took on the aspect of what we today call planetariums.

  Today we may not appreciate lines like

  A murky manger [Cancer] with both stars

  Shining unaltered is a sign of rain.

  If while the northern Ass [Pegasus] is dimmed

  By vaporous shroud, he of the south gleam radiant,

  Expect a south wind; the vaporous shroud and radiance

  Exchanging stars harbinger Boreas [the Wind].9

  But in ancient Greece and Rome these lines were repeated by many lips over the centuries. Aratus’s Phaenomena was the third most widely read book of the classical era after the Iliad and the Odyssey. In 89 BC, the Roman philosopher-orator Cicero translated it into Latin; a century later, the Roman poet Ovid followed with another translation. In AD 15, the popular and learned Roman general Julius Caesar Germanicus, eventually the adopted son of Tiberius, retranslated and updated the Phaenomena from his armed camp between military engagements. The book caught the fancy of the upper classes of Rome just as it had that of the aristocrats of Athens. It soon became, writes one scholar, “the polite amusement of the Roman ladies to work the celestial forms in gold and silver on[to] the most costly hangings.”10 Late in the first century AD, the apostle Paul, preaching to a crowd from the steps of the Acropolis in Athens, turned Aratus’s Hymn to Zeus that begins the poem into a hymn to the Christian God and paraphrased it thus: “In Him we live, and move, and have our being; as certain also of your own poets have said, for we are also His offspring.” This text appears in Acts 17:28.

  There were more Latin translations. Fifty original manuscripts of Phaenomena are extant in museums around the world today, and there are numerous modern editions.*46

  The treatise on which Aratus’s Phaenomena was based—the Phaenomena of the astronomer Eudoxus of Cnidus, written in 366 BC—did poorly compared to its successsor. The text has long been lost; we know something of its contents because Hipparchus (ca. 190–120 BC) summarized it and Aratus’s poem in a Commentary in which he gave both works a lambasting. The Alexandrian astronomer Ptolemy (ca. AD 90–168 ) swept much of Hipparchus’s Commentary up into his magisterial compendium of astronomical lore called the Almagest. Almagest means “Greatest Book” and is the title the Arab translators of the book bestowed on Ptolemy’s work. This “greatest book,” famous for its elegant and definitive description of the geocentric or “Ptolemaic” universe, was the astronomy textbook of record for the Middle East, Asia, and Europe up until the sixteenth century. In Newton’s day it was still required reading.

  That is how knowledge of the Eudoxean-Aratean constellation catalogue may have made its way into the English village of Grantham where Isaac Newton went to school—if it did make its way into the school. We can’t be sure it did. We do know that the Grantham school was a very well-equipped school by any standard, and if a copy of Ptolemy’s Almagest lay on one of its bookshelves, Newton likely had a look at it. And if the book wasn’t there, Newton would have eagerly perused a copy early on
in his career at Cambridge, which would have led him to Aratus’s Phaenomena.

  Let’s recall the star globe newly delineated with constellations that, Isaac Newton was certain, Chiron the centaur had given Jason at the time of the launching of the expedition of the Argonauts in search of the Golden Fleece.

  Let’s also recall the “primitive sphere” on which, legend has it, Eudoxus based his description of the stars in the Phaenomena.

  Isaac Newton decided they were one and the same sphere, which meant that the constellations as described by Eudoxus and by Aratus were in the same positions in the night sky as those on the star globe fashioned by Chiron the centaur. And, since Chiron had, or so Newton believed, traced out the constellations and marked them on his star globe in the same year that the Argo sailed, then the constellations as Eudoxus and Aratus described them were a picture of the night sky in the same year that the Argo set sail.

  Because this globe indicated, along with the location of the stars, the position of the equinoctial and solstitial lines relative to the rising and setting of the sun, Newton could use those phenomena to determine the actual, historical year when the expedition of the Argonauts sailed.

  Newton believed Chiron the centaur had created the first star globe. And Newton believed that the “primitive sphere” pointed toward a “first” star globe. Moreover, Newton came up with proof—or so he thought—that Chiron, along with his many other accomplishments, was an astronomer.

  Sometimes we get the impression that there were certain brilliant men of high antiquity who got themselves born solely to supply Isaac Newton, a couple of millennia later, with the one, tiny, obscure, but indispensable fact he needed to confirm one or another of his more daring hypotheses.

  Such a man was Saint Clement of Alexandria (AD 150–213), founder of the famous Empathetical School at Alexandria. Clement’s Stromata (“Patchworks”) was the definitive text for those who believed all Greek science and philosophy originated with the Jews. Along with much that was conventional, it was as crowded with esoteric, eccentric, and anonymous facts as an ancient map of the globe is packed with griffins, mermaids, dragons, unicorns, and headless cannibals with mouths in their chests.