The Cave and the Light

by Arthur Herman

  The inquisitors looked the letter over. They said, This is a copy.

  I’ll produce the original if you want, Galileo said. It’s here in Rome. And eventually he did, signed in Bellarmine’s own hand.44 Far from ordering Galileo silenced, it gave him leeway to talk about Copernicus as much as he wanted as long as he did not assert that the heliocentric theory was absolutely true. Far from disobeying any papal injunction, it looked as though Galileo had been following the letter of the law, if not necessarily its spirit.

  Galileo had won. The inquisitors were beaten.45 The 1616 injunction was not signed, and some were beginning to suspect it might be a forgery. Not a single witness stepped forward to support the charges against Galileo, not even his worst enemies. All the other witnesses, including Bellarmine, were deceased.46

  The Inquisition dithered for weeks. Finally it approached Galileo in private. Their prestige was at stake, said the inquisitors. Couldn’t he admit to some wrongdoing so that they could find him guilty, with the understanding that he would be treated with full and complete leniency?

  Galileo, confident that he had his enemies over a barrel, agreed. He publicly admitted that some portions of the Dialogue had gone too far in its espousal of Copernicus’s theory. He then asked, with perhaps a slight wink to his judges, for leniency on account of his infirmity and advanced age. So it was with a sense of shock that he received, instead of some light penance, a sentence of indefinite imprisonment (although that was commuted within days to house arrest).

  Galileo was devastated. As for the Catholic Church, it had wrought a public relations disaster. Three of the ten Inquisition judges refused to sign the sentence, which they knew to be a travesty of justice.47 The archbishop of Siena immediately offered to take Galileo into his residence on his own recognizance. A year later Galileo was finally allowed to return home, although he would spend the rest of his life living under supervision by agents of the Inquisition.

  However, this did not stop him from finishing his final work on mechanics and physics, Dialogues Concerning Two New Sciences in 1638, four years before his death. Down to the end, Galileo protested that he was a better Aristotelian than his opponents because he believed in avoiding fallacies in reasoning, and because he believed “it is not possible that sensible experience is contrary to truth.” All the same, his last work had to be printed not in Italy, but in Leyden in Calvinist Holland. Galileo himself never got to see a copy.48

  For the Church, it was a bitter irony. It had condemned Galileo in order to prevent the Reformation’s overthrow of Aristotle from spreading to the study of nature. Instead, Galileo’s condemnation cemented the alliance between the new science and Protestantism. With the help of the printing press, Galileo and Copernicus took the intellectual bastions of Protestant Europe by storm. Mathematical mechanics set the new rules for scientific study, from astronomy and physics to chemistry and botany.49

  Galileo had lost his fight; his new science had won the war. In John Milton’s England, Galileo, “the Tuscan artist” with his “optic glass,” passed into literature and legend:

  Like the moon, whose Orb

  Through optic glass the Tuscan artist views

  At evening from the top of Fesolè,

  Or in Valdarno, to descry new lands,

  Rivers, or Mountains, in her spotty Globe.50

  This was perhaps the final irony. Galileo the obedient Roman Catholic became an overnight Protestant hero. He would be remembered as a champion not only of science, but of the principle of free inquiry versus papist tyranny, in Milton’s words “a prisoner to the Inquisition for thinking in astronomy otherwise than the Franciscans and Dominicans licensed.”51

  It was easy to forget that it was the Church’s favor that had enabled Galileo to rise so high in the first place, only to fall so far.

  * * *

  * Vincenzo went further than this. Orthodox music theory stated that the ratio of 2:1 applied to strings that were tuned an octave apart as well. Vincenzo proved this was wrong by a series of experiments with weights tied to lute strings, which showed the ratio was actually 4:1. Scholar Stillman Drake argues that Vincenzo’s son was living at home at the time, tutoring students in mathematics, and may have helped his father run the experiments.

  † See chapter 2.

  ‡ Did he drop them off the Leaning Tower of Pisa, as legend claims? Historians used to scoff at the story. However, it came from a former student of Galileo who claimed to be present, and Galileo certainly was inclined to do spectacular experiments not just to impress his students, but to try to convince his fellow professors. We do know that in 1612, a professor of philosophy did drop balls off the Leaning Tower in order to prove Galileo wrong—with disappointing results.

  § See chapter 7.

  ‖ Bruno’s belief in Egyptian magical religion, which he shared with Ficino, would go on to become a key ingredient in Freemasonry.

  a There was also an ancient commentator on Aristotle named Simplicius, whose study of the Physics and On the Heavens were scholastic staples.

  Title page of Isaac Newton’s Principia Mathematica, 1687

  Twenty

  GOD, KINGS, AND PHILOSOPHERS IN THE AGE OF GENIUS

  In God’s House (which is the universe) are many mansions.

  —Isaac Newton

  Where law ends, tyranny begins.

  —John Locke

  We talk a lot about rights in modern society. Some say too much. We have civil rights, human rights, legal rights, even animal rights. This way of talking, too, comes out of the struggle between Plato and Aristotle, but in a more complicated way than, say, the emergence of medieval logic or the Renaissance. This is because as European civilization advanced, the influence of Plato and Aristotle would reflect more and more in the spirit and less in the letter of people’s thinking. It is also part and parcel of the age of new science Galileo had launched.

  Galileo died in 1642. He was buried in Florence in the Church of Santa Croce, directly opposite the tomb of Michelangelo. This is only right, since together they had remade the Renaissance world in a distinctly Platonist frame.

  Galileo’s new science showed it was possible to think of that higher order not just in religious or artistic terms, as Michelangelo had, but in mathematical terms of the utmost precision. It was a precision that also explained how nature worked far better than Aristotle could. When a nineteen-year-old mathematical prodigy named Isaac Newton arrived at Cambridge University in 1661, Galileo’s insight that mathematics could explain the workings of nature in terms of geometric mechanical motion had carried away the imagination of northern Europe.

  What was true of planets and soccer balls, men realized, might also be true of plants, animals, and the formation of minerals. Mathematical mechanics might even explain the workings of the human body—as the English physician William Harvey discovered when he realized that the circulation of the blood followed the laws of hydraulics and that the human heart was nothing more than a mechanical pump.

  Aristotle’s science of final causes wasn’t just dead. Except among a few diehard stragglers, it was as if it had never existed. What was left in people’s minds was a universe that looked like one of those magnificent cathedral clocks we find in cities in Germany and Switzerland. Great descending weights run the clock hands as they turn on their axles; mechanical men blow horns and ring bells; doors open and saints appear. Mechanical angels circle and turn on grooved tracks, and mechanical cocks lift their wings to crow out the hour and half hour with daily precision.1

  It all looked very impressive. It was also, as Galileo and Kepler had both shown, finely tuned and programmed. However, something was missing, what we might call the human factor. Where did humanity fit into all this? Where does a cosmos governed by impersonal mechanical laws leave us as rational creatures?

  Harvey’s fellow Englishman, Sir Francis Bacon, supplied one answer: It leaves us firmly in charge. As self-declared pundit of the new science, Bacon was delighted to see Aristotelian na
tural philosophy with its “contentiousness” (an odd complaint from a lawyer) and its fetish for words, not deeds (ditto), get swept away.2 Now men could get down to the business of forcing Nature to reveal her secrets for our use, Bacon said. He liked to speak of putting Nature “on the rack” through constant experiment and verification, like a helpless prisoner being questioned in front of a judge and jury. “Nature exhibits herself more clearly,” Bacon wrote, “through the trials and vexation of art than when left to herself.”3

  Across the English Channel, the biggest champion of the new mechanical worldview was René Descartes. Bacon was entirely ignorant of mathematics. Descartes was steeped in it. Reducing the operations of the universe to a series of lines, circles, numbers, and equations suited his reclusive personality. His most famous saying, “I think, therefore I am” (cogito, ergo sum), could be stated less succinctly but more accurately as “Because we are the only beings who do math, we rule.”

  For Descartes, the essence of mind is to think, and the essence of matter is to exist—and the two never meet. The physical world around us is governed by exact and necessary laws imposed by God, which we watch, analyze, and manipulate. Otherwise, nature never touches us at any point. “What is beyond geometry, is beyond us,” as Blaise Pascal once put it—and therefore is of no interest to us. Descartes’s worldview makes us spiders at the center of an enormous web not of our making. Or in his other famous formulation, we are the ghosts in the machine: souls in a world machine that operates inexorably and impersonally according to the laws of geometry and mechanics, while we operate the levers and spin the dials.

  Before his death in 1650, Descartes had spread Galileo’s fame up and down Europe, and with it the mechanical philosophy. In France and Holland, Cartesianism became virtually the official creed of scientists, mathematicians, and everyone else involved in the investigation of nature.4 Descartes’s books found eager readers in England, including the father of modern chemistry, Robert Boyle, and a shy, rather retiring teacher at Cambridge named Henry More.

  More was very impressed by Descartes. Other modern philosophers, he wrote to a friend, “are mere shrimps and fumblers in comparison [with] him.”5 Yet the more he read, the more More had his doubts.

  More couldn’t help comparing Descartes’s view of man and the universe with those of another author he revered, Marsilio Ficino. Descartes’s dualism, his way of seeing the world as shaped by the action of the soul on matter, bore a superficial resemblance to Ficino’s and also Plato’s. However, while Ficino’s message seemed full of life and hopeful possibility, Descartes’s seemed positively gloomy. Matter in Descartes had become an inert oppressive presence, doing its job in a reliable robotlike way but surrounding and confronting us with its essential lifelessness everywhere we look—even in the eyes of our favorite pets.*

  Where do we find love and comfort in this comfortless, mechanical world? And above all, More wanted to know, where is God?

  Descartes’s answer was confident and pat. God was the omnipotent Legislator who has made everything and installed all the necessary rules that govern the universe, including the laws of mathematics, rather the way the manufacturer installs software on a new Android. Then God steps aside and lets His creation “do its thing.” As part of the original installation, God has also put the idea of His existence into our minds.6 But we can go for months or even years without clicking on that particular icon. And if we don’t click on it, More realized, then we may never notice what’s missing.

  Descartes was no atheist. But More worried that his view of the world must inevitably lead to atheism. It was simply not possible that God would set up the cosmos and then walk away—and men should not be allowed to think so. In a universe in which everything has its place, He must still be somewhere.

  But how to prove it? More and his friends, the so-called Cambridge Platonists, were stumped. Then in 1661 there arrived in their midst the young man who would, surprisingly enough, give them with the answer.

  I say surprisingly, because Isaac Newton was hardly the person people would pick to be the cultural guru of his age. Everyone recognized that this son of a clergyman from northwestern England (born the same year Galileo died, in 1642) was an incredible math prodigy. He was twenty-seven when he took the prestigious Lucasian chair of mathematics at Cambridge. His predecessor willingly resigned in recognition of Newton’s genius.7

  The new Lucasian professor lectured to a largely empty classroom. The mathematical theories he expounded were so complicated, no student could follow him. Newton was also deeply secretive. He hid all his most important research from his colleagues and even friends. He invented integral calculus and used it for years in his own work, before finally, reluctantly, he was forced to let the rest of the world in on the secret.8 And every minute Newton didn’t spend working on optics, physics, astronomy (including inventing the reflecting telescope), some harmless alchemy, and other sidebars of his mathematical discipline, he spent furtively studying the Bible and church history.

  After Newton’s death in 1727, when he was the acknowledged scientific genius of his age, the dozens of folio notebooks he had filled with his biblical studies were discovered. People shook their heads. The last stages of a great mind sliding into senility, they concluded. Some even said they were the deluded products of mercury blood poisoning from Newton’s years of chemical experiments.

  The truth was that Newton’s biblical research was central to his entire scientific career. They form the essential backdrop for his most famous work, the Principia Mathematica. For like a true son of Plato, Newton never lost sight of the Big Picture, including the problem that had so perplexed Henry More and the other Cambridge Platonists. Where do we find God in a material and mechanical universe?

  Descartes’s works had helped to push Newton’s mind away from pure mathematics toward the problems of the new science like optics. Then in the late 1660s, Newton turned decisively against him. The “notion of bodies having, as it were, a complete, absolute, and independent reality in themselves,” he decided, was not only misleading but dangerous. By separating body from mind and spirit, Descartes was denying the dependence of the material world on God’s will and His providence. “A God without dominion, providence, and final causes,” Newton later wrote, “is nothing else but Fate.”9

  By denying God, we deny our own spiritual freedom. We surrender ourselves to a world of pure material necessity. The intellectual tyranny that Newton had seen in the darkest chapters in the history of the medieval Church, he saw repeated in the tyranny of a godless, soulless science. He intended to correct that view and free men’s minds for the future.

  It was this goal that finally persuaded him to agree to publish his decades of research in physics, as The Principles of Nature Mathematically Explained, or the Principia Mathematica, in 1687—incidentally, the last major work of Western civilization written entirely in Latin. Most read it as the last word on Galileo’s new science, as it set out the mathematical laws of nature that governed everything from the movement of the planets and comets to fluid mechanics and the lunar tides. From start to finish, however, Newton’s own goal was to demonstrate the dependence of matter on God.10

  He did this through his revolutionary concept of force. Nature as described in the Principia is a complex matrix of forces, from centripetal and centrifugal force, to magnetic force and inertial force (as in, “Bodies at rest tend to remain at rest”), to the most famous of all, the force of gravity. These forces, Newton showed, exert a palpable and mathematically predictable influence on the behavior of all physical bodies. Yet they are entirely invisible and beyond any purely physical or mechanical explanation.

  Descartes’s clockwork universe couldn’t account for them. Newton’s universe could. The Principia is the culmination of Galileo’s insight that if you can describe something mathematically, then it must exist. Newton never tried to give an explanation for gravity. “To us,” he wrote, “it is enough that gravity does really exist, and act[s]
according to the laws we have explained.…” All the same, “gravity must be caused by an agent acting according to certain laws.”11 The identity of that agent was self-evident to Newton. It was God.

  Nature’s laws implies a lawgiver: it’s an idea as old as the Bible or Plato’s Timaeus. However, Newton now carried this further by making the physical nature of the cosmos itself proof of God’s spiritual presence. “He is omnipresent,” Newton wrote. “In Him are all things contained and moved; yet neither affects the other; God suffers nothing from the motion of bodies; bodies find no resistance from the omnipotence of God.” In other words, the rich diversity of nature, combined with its symmetry and regularity, reflects the will of a benevolent God.12

  Newton’s God is a God who constantly watches over His creation. He provides it with universally true general laws, then thoughtfully provides man with the means to decipher them, namely reason. Newton also finally answered Henry More’s question about where God Himself was in this meticulously ordered universe. He is in between. His spirit provides the space through which all objects pass, from birds and trees to comets and stars in the sky; and His infinitude is found in the infinity of the cosmos, stretching out beyond our solar system into eternity. “He is not duration and space, but He endures and is present.… He exists always and everywhere.”13

  The fact that the study of nature proved beyond refutation the existence of a perfect and benevolent Creator was for Newton both exhilarating and liberating. Men could now move forward with a new freedom, confident that such a Supreme Being supervised and guided the complex workings of the universe, including their own actions.