Only the educated are free.
—EPICTETUS, FIRST CENTURY AD
Works, not Words;
Things, not Thinking…
Operation, not merely Speculation.
—CHEMIST GEORGE THOMPSON, 1660s
Prior to the rise of science there were, as Aristotle noted, only two valid ways to evaluate the merit of an idea—by critiquing its internal logic, or by comparing it to other ideas. Science offered a third option, that of testing ideas through controlled experimentation. A telling experiment might put an end to disputation, by obtaining answers directly from nature.
The conducting of scientific experiments takes time, money, and (since most experiments fail) perseverance. To support it requires of society a degree of affluence plus an appetite for innovation and change. These conditions most often arose where states vigorously competed against one another through trade, which created wealth and promoted technological and financial innovation. Scientific experimentation should therefore be expected to have first appeared in a region that combined diversity and competition, even to the point of strife, with a geography favorable to trade—a region of long coastlines, natural seaports, and proximity to foreign lands from which its people acquired a taste for the exotic and the unfamiliar. The European region that best fit those criteria was Italy.
The Italian Renaissance, generally dated from the 1400s, was kick-started by the fall of Greece and the rest of Byzantium to the Turks in 1453, an upheaval which sent thousands of Byzantine art treasures and books—notably ancient Greek and Latin manuscripts—westward by ship to the markets of the Italian peninsula. Italy was not yet a nation but a set of city-states, renowned for their vitality and their enthusiasm for liberty and independence. In Ferrara it was being said as early as 1177 that “our liberty, which we have inherited from our forefathers, we can under no circumstances relinquish, except with life itself.” The watchwords of Florence—whose celebrated poet Dante Alighieri called freedom “God’s most precious gift to human nature”—were libertas and libertà. These stirring slogans meant that citizens (a small minority of the population) had certain legal rights, and that each city-state asserted a right to govern itself rather than to be dominated by the Spanish, the French, or any other distant power. Although no Italian city-state would be called a democracy by modern standards, the circumstances within and among them produced a profusion of social experimentation, with one city-state after another oscillating between republicanism, limited democracy, and reversions to various authoritarian forms of government. Pisa, Milan, Arezzo, Lucca, Bologna, and Siena were all at some point governed by elected officials, while Florence flirted with republicanism and Venice tried various parliaments and councils to sufficient effect that William Wordsworth, ruefully surveying the fall of the Venetian Republic to Napoleon in 1797, called her “the eldest child of liberty.” Innovation and trade created new wealth and propelled merchants and artisans into the ranks of the aristocracy. This economic mobility lent a meritocratic cast to even the Kingdom of Naples—of which the prominent seventeenth-century attorney and amateur scientist Francesco D’Andrea declared, “There is no city in the world where merit is more recognized and where a man who has no other asset than his own worth can rise to high office and great wealth…without having to depend on either birth or money to get there.” Amid such social tumult, the scions of old wealth took care to at least outwardly observe an “equality of aristocrats” that embraced the newly wealthy on equal terms; even the Doge of Venice found it advisable to dress like a merchant and be bowed to only in private. The author and libertine Giacomo Casanova, whose personal preferences ran to luxury, was amused by the egalitarian appearance affected by the Venetian nobles but understood its utility:
It is impossible to judge of equality, whether physical or moral, except by appearances; from which it follows that the citizen who wants to avoid persecution must, if he is not like everyone else or worse, bend his every effort to appearing to be so. If he has much talent, he must hide it; if he is ambitious, he must pretend to scorn honors; if he wants to obtain anything, he must ask for nothing; if his person is handsome, he must neglect it; he must look slovenly and dress badly, his accessories must be of the plainest, he must ridicule everything foreign; he must bow awkwardly, not pride himself on being well-mannered, care little for the fine arts, conceal his good taste if he has it; not have a foreign cook; he must wear an ill-combed wig and be a little dirty.
The city-states’ vigorous competition with one another often escalated into war and rebellion. Their hardball politics was exemplified in the works of Niccolò Machiavelli, a career diplomat who negotiated the surrender of Pisa to Florence but wound up being tortured on the rack by the Medici. In his book The Prince, which he wrote upon retiring to the country after having lost one political battle too many, Machiavelli advises that “it is far safer to be feared than loved,” adding that “being unarmed…causes you to be despised” and that “a prince ought to have no other aim or thought…than war.” Small wonder that Baldassare Castiglione, in his internationally popular A Manual for Gentlemen of 1528—a book praised for its “civilizing” influence—observed that “the principal and true profession of a courtier ought to be in feats of arms.”
But Castiglione added that “the principal matter…is for a courtier to speak and write well.” To minimize crippling losses of blood and treasure, the Italian city-states did two things. First, they trained some of the world’s first professional ambassadors, nurturing staffs of political advisors to guide their leaders and advertise their civic virtues—especially “civic humanism,” the idea, prominent in liberal democracies today, that citizens should devote time to government service. Second, they promoted their ongoing competition in technology and the arts as a peaceful and profitable alternative to war.
The artists of the Italian Renaissance were often involved in such political competitions. Michelangelo’s larger-than-life sculpture David was commissioned, in 1501, to celebrate the establishment of a republican government in Florence, which had just freed itself from rule by the anti-Renaissance book burner Fra Girolamo Savonarola. Leonardo da Vinci, the original Renaissance man, secured a position in Milan by writing a long letter to the mechanically inclined Duke Lodovico Sforza that stressed his abilities as an inventor and military engineer, mentioning only in passing that he was also an artist. Leonardo was being candid: The painter of the Mona Lisa (which he never finished) did not in fact much like to paint, and was impatient with the fine arts generally. He preferred to work on plans for his many mechanical inventions—a pile driver, an automobile, a helicopter, a parachute, a diving bell, a robot, and various military defense systems. Leonardo’s penchant for experimentation extended to his artwork, sometimes with unfortunate results. His fresco Battle of Anghiari, done with a high-gloss oil technique of his own invention, reportedly failed to dry and ultimately slithered off the wall, vanishing entirely within fourteen years. His inventions ran so far ahead of existing technology that few could be built, much less tested, while he was alive. As the historian John Herman Randall Jr. remarked, Leonardo’s “thought seems always to be moving from the particularity of the painter’s experience to the universality of intellect and science, without ever quite getting there.”
In short, the Italy that created the Renaissance was a fragmented and disputatious gaggle of city-states that contended using every weapon they could lay their hands on, from daggers and cannons to frescoes and carved marble, their experimentation producing a torrent of political, artistic, and ultimately scientific creations. The Republic of Venice in the fifteenth century built the world’s best ships and was known for its fabrics, leather goods, and glass—its glassmakers tellingly if falsely advertising that their elegant goblets would shatter on contact with poison. Florence, hampered by a landlocked geography except when it controlled Pisa, created limited-liability partnerships for investment in the manufacture and trade of leather goods and wine and became an international center of banking and finance. Bologna invented hydraulically powered silk mills and operated more than a hundred of them, producing a million pounds of raw silk annually before the trade secret got out and was adopted by competitors. Milan, a major exporter of silk, velvet, wool, brocade, and military armor, impressed visiting Londoners who noted with astonishment that the Milanese sported over a thousand horse-drawn coaches elegant enough to turn heads back home. The papermakers of Genoa, expanding production to meet the growing appetites of an increasingly literate public, were operating a hundred paper mills by the end of the sixteenth century. By 1680, when Antonio Stradivari set up his violin-making shop in Cremona, the trade boom was slackening. Portuguese and Spanish navigators had opened up water routes to Asia around Africa, blunting the Italian advantage and putting Venice into decline, while in the Mediterranean the trading companies of Holland and England were offering fast maritime transport at competitive prices. Nevertheless, the skills acquired by Italian craftsmen kept them in the high-end luxury market, where their descendants continue to thrive today.
Many of the great Renaissance artists were men of common origins who resented being condescended to by aristocrats and by the scholars who aped aristocratic manners. Complained Leonardo, the illegitimate son of a liaison between a lawyer and a young lady said to have been a household servant:
I am fully aware that the fact of my not being a man of letters may cause certain presumptuous persons to think that they may with reason censure me, alleging that I am a man without learning. Foolish folk! Do they not know…that my subjects require for their exposition experience rather than the words of others?…Though I have no power to quote from authors as they have, I shall rely on a far bigger and more worthy thing—on experience, the instructress of their masters…. And if they despise me who am an inventor, how much more should they be blamed who are not inventors but trumpeters and reciters of the works of others.
Michelangelo—a brusque, muscular workman who went for months without bathing or taking off his dogskin boots, and whose conspicuously broken nose resulted from a fistfight—was similarly quick to take offense. When Leonardo made fun of him, joking with friends who were disputing some lines of Dante in front of the Palazzo di Gavina that “Michelangelo will explain it to you,” Michelangelo’s response was to question not Leonardo’s art but his technological ability: “You designed a horse to be cast in bronze and, as you could not cast it, you abandoned it from shame—and those stupid Milanese believed in you.” The peerless goldsmith Benvenuto Cellini was a hooligan who boasted in his autobiography of killing four men and of reducing wealthy noblemen to near-groveling as they vied to get him to accept their commissions. Although Cellini’s tales smack of exaggeration, they capture the frustration felt by many artists and artisans whose dexterity brought them money and recognition but inadequate social status.
The making and accounting of money helped advance quantitative modes of analysis without which science might otherwise have stalled at a merely descriptive level. Florentine bankers, Milanese merchants, and Venetian traders created important innovations such as double-entry bookkeeping—which their successors learned from Luca Pacioli’s authoritative Summa de Arithmetica, first published in Venice in 1494—while technological improvements pioneered by the Genoese, Florentine, and Venetian mints gained their coins an international reputation for reliable weight and purity. The minting of money became a subject of scientific interest, with Nicolaus Copernicus publishing a treatise on coinage in Poland in 1526 and Isaac Newton taking control of the London mint from 1699.
Once the printing press had radically reduced the cost of books, scientific and technological innovators found that there was money to be made by writing for the public, in the vernacular rather than Greek or Latin. Their popular books made an end run around the authorities, setting the stage for a dramatic confrontation between tradition and the emerging forces of innovation and creativity. It came in Italy. Its martyr was Galileo.
A born scientist, lifelong experimenter, and compelling writer, Galileo Galilei presented a triple threat to the professors and priests whose careers were invested in the proposition that everything worth knowing could be found in ancient books. (Galileo said that they studied “a world on paper,” whereas his experiments revealed “the real world.”) His iconoclasm appears to have been inherited from his father, the merchant, musician, and mathematician Vincenzio Galilei, who wrote papers disputing scholarly opinions about music that conflicted with experience. When his former teacher Gioseffo Zarlino asserted that the semitone cannot be divided into two equal parts—because to do so meant invoking an irrational number, which is to say a number that cannot be expressed as the ratio of two integers, a Christian taboo—Vincenzio countered that since any capable musician could hear such tones, a mathematical theory that denied their existence must be flawed. To test the prevailing claim that two strings of equal lengths which sound an octave apart must differ in tension by the ratio 2:1, Vincenzio suspended various weights from lyre strings and found that the ratio actually is 4:1. So the young Galileo had plenty of opportunity to see how experimentation could overturn the opinions of scholars.
Sent to study medicine at the University of Pisa, Galileo soon lost interest and resorted to tinkering on his own. When a concerned Vincenzio came down from Florence and found his son immersed in experiments that had little to do with his schoolwork, he bowed to the inevitable and let the boy come home. A period of free investigation followed, during which Galileo paid particular attention to pendulums—a natural step, given his father’s penchant for investigating music by hanging weights from strings. These experimentations eventually led to several important discoveries. One was “isochronism”—that a pendulum takes the same time to complete each swing, whether moving rapidly in a long arc or slowly in shorter arcs. (Isochronism suggested to Galileo that pendulums could be employed to make more accurate clocks, as they were from 1656, when Christiaan Huygens patented one.) Another finding opened the door onto gravitational physics. Galileo suspended pendulum bobs of differing weights from equal lengths of wire, and discovered that the light ones (made of cork) swung at almost the same rate as heavy ones (made of lead). Even when one ball was “a hundred times heavier” than the other, he reported, they swung in step. To test the matter further, he rolled balls down parallel inclined planes and got the same result: Regardless of their weight, they all rolled to the bottom at the same rate.
This seemingly minor observation had epochal implications. The Aristotelian professors taught that heavy objects fall faster than light objects, as everyday experience indicates. Owing to air resistance, coins dropped here on earth fall faster than feathers do. Galileo’s experiments minimized the effect of air resistance, allowing him to glimpse the truth—that gravity accelerates all objects at the same rate, regardless of their mass. With that, Galileo the college dropout opened a door for future scientists from Newton to Einstein and beyond.
Galileo’s lack of a degree frustrated his initial efforts to secure a teaching position—he was turned down by the universities of Siena, Bologna, and Florence—but he eventually landed a mathematics lectureship at Pisa, and then a higher-paying post at Padua. Padua was part of the free republic of Venice, and Galileo’s indifference to authority and vivid rhetorical style made him a favorite among the students there. The advancement of military technology was a priority in the Venetian republic, and Galileo soon supplemented his income by making inventions. He frequented the Venice arsenal, one of the world’s most advanced centers for the construction and outfitting of ships, and garnered a commission to study the physics of oars. He invented a compass for aiming cannons, a horse-driven water pump (patented in 1594), and a thermometer, eventually setting up a small business for the manufacture of scientific and military instruments.
In May 1609, having learned that telescopes were being fashioned in the Netherlands, Galileo began making telescopes of his own, turned them on the sky, and embarked on observations that demolished the Aristotelian universe. That model, fashioned in the fourth century BC by Aristotle and the Greek astronomer Eudoxus and refined by Claudius Ptolemy of Alexandria in the second century AD, placed the earth at the center of the universe and depicted the sun, moon, planets, and stars as waferlike discs attached to revolving crystalline spheres. The terrestrial realm had four elements—earth and water, whose gravity made them go downward, and air and fire, whose levity inclined them to rise. Everything above was made of a fifth element, ether, which obeyed a physics all its own. The first four elements could change, but ether could not: Hence the earth was dynamic and the heavens immutable. Flaws in this official cosmology had been observed in the behavior of comets, whose elliptical orbits required that they fly right through the crystalline spheres, and novae—“new” stars, which are actually old stars that explode and become bright enough to be seen for the first time with the unaided eye. When a nova appeared in 1604, Galileo gave three public lectures about it, pointing out that any new apparition in the heavens violated the Aristotelian proscription against change among the heavenly spheres. Such occasional anomalies could be explained away by learned Aristotelians in the Vatican and at the colleges, but Galileo’s telescopic observations ended the argument—or should have. The moon displayed rugged mountains, like the earth’s, only craggier, and in no way resembled an ethereal wafer. Venus displayed phases like the moon’s, indicating that it pursues an orbit around the sun, inside Earth’s orbit, just as depicted in the Copernican cosmology.
Galileo’s book presenting these observations, Sidereus Nuncius (“Messages from the Stars”), created a sensation. With the Italian city-states competing for geniuses in something like the way that its cities today vie for football stars, a newly famous Galileo could take his pick of academic appointments. But he assumed, as scientists sometimes do, that politics was simpler than science, and so made a series of political miscalculations.
His first mistake was to underestimate the value that liberalism afforded him as a citizen of the Venetian Republic. The University of Padua offered him tenure at double his previous salary, but he instead negotiated an appointment with Cosimo II, the Grand Duke of Tuscany, whom he had once tutored in mathematics—in effect bartering away his liberty for the glamour of a court position and the luxury of no longer having to teach undergraduates. “It is impossible to obtain wages from a republic, however splendid and generous it may be, without having duties attached,” he mused. “I can hope to enjoy these benefits only from an absolute ruler.” His friend Giovanni Sagredo, a career diplomat, warned Galileo about leaving a free republic for “a place where the authority of the friends of the Jesuits counts heavily”—the Jesuits having been banished from the Venetian Republic. “I have seen many cities,” Sagredo added, “and truly it seems to me that God has much favored me by letting me be born in [Venice]….
Here the freedom and the way of life of every class of persons seem to me an admirable thing, perhaps unique in the world…. Where will you find the freedom and sovereignty you enjoy in Venice? In the tempestuous sea of a court, who can avoid being…upset by the furious winds of envy?
But Galileo was already sailing into political seas about which he remained blithely ignorant. “I deem it my greatest glory to be able to reach princes,” he wrote fawningly to Cosimo’s secretary of state, Belisario Vinta. “I prefer not to teach others.”
In the end it was the Dominicans rather than the Jesuits who persecuted Galileo, but by that time he had managed to provoke them both, and many other clerics besides. Having railed against the professorial “fools” and “blockheads” who refused to look through his telescopes, Galileo now trained his withering scorn on Vatican officials who clung to the old cosmology—an amateur mistake that left them no honorable path of retreat. He put too much faith in personal contacts: Cosimo was his former pupil and the Pope a personal friend, but rulers, like the states they govern, act on their interests rather than their friendships. Part of it was pride. Unlike Einstein—who could joke that “to punish me for my contempt for authority, Fate made me an authority myself”—Galileo hardened into the position that all his opinions, even flawed ones like his mistaken theories of tides, ought to be accepted on the strength of his personal authority alone. Believing in the ultimate rationality and goodwill of the Church, he thought that earnest churchmen, once acquainted with the facts, would cease to mislead their parishioners. When the Vatican banned his books and summoned him to the Inquisition, Galileo wrote to the Pope’s nephew Cardinal Barberini that
the prohibition of the printing and sale of my Dialogues has been a cruel blow to me [and] depresses me to such an extent as to make me curse the time I have devoted to these labors—yes, I regret having given to the world so much of my results. I feel even the desire to suppress, to destroy forever, to commit to the flames, what remains in my hands. Thus I should satisfy the burning hate of my enemies.
This bluff the hardened veterans of Vatican politics were prepared to call.
All the world knows the rest of the tale: Threatened with torture, a seventy-year-old Galileo knelt before the Inquisition, recanted such “errors and heresies” as having maintained the “false opinion that the sun is the center of the world and does not move and the earth is not the center of the world and moves,” and spent the rest of his life under house arrest—where, nevertheless, he continued to experiment with pendulums. But the reason the world knows the story is, of course, that Galileo’s side—the side of free speech and unencumbered investigation—won. His research demonstrated that nature is more intriguing, and its study more rewarding, than had been thought—a lesson that would not be lost on Isaac Newton, born the year Galileo died. By publishing in the vernacular, so that ordinary people could “see that just as nature has given to them…eyes with which to see her works, so she has also given them brains capable of penetrating and understanding them,” Galileo helped establish the liberal, antiauthoritarian ethos of modern science. “The modern observations deprive all former writers of any authority,” he declared, “since if they had seen what we see, they would have judged as we judge.” In this he resembled the English physicist and physician William Gilbert, whose work he admired. Gilbert’s treatise on magnetism, published in 1600, stressed the efficacy of experimentation:
In the discovery of secret things and in the investigation of hidden causes, stronger reasons are obtained from sure experiments and demonstrated arguments than from probable conjectures and the opinions of philosophical speculators…. Men are deplorably ignorant with respect to natural things, and modern philosophers, as though dreaming in the darkness, must be aroused and taught the uses of things, the dealing with things; they must be made to quit the sort of learning that comes only from books, and that rests only on vain arguments from probability and upon conjectures.
Following Galileo’s persecution by the Church, the scientific epicenter shifted from the Catholic south to the Protestant north. The poet John Milton, who visited Galileo at the villa outside Florence where he was being confined, wrote that the “tyranny” of the Inquisition had “dampened the glory of Italian wits.” By the close of the seventeenth century, when important scientific works were being published in the north and Anglican ministers were preaching that science could be reconciled with religion, scientists in Naples were being arrested and tried for maintaining “that there had been men before Adam composed of atoms equal to those of other animals.”
Every age since has produced its own martyrs to science. The chemist Joseph Priestley, skeptical about certain religious dogmas, was driven out of Birmingham in 1791 by rioters who sacked his house and destroyed his laboratory. Charles Darwin long suppressed his theory of evolution rather than face the religious indignation that indeed greeted its eventual publication. More than a hundred members of the Soviet Academy of Sciences were imprisoned, and some of them executed, for failing to toe the party line. The American mathematician Chandler Davis, a member of the Institute for Advanced Study at Princeton, spent six months in jail for refusing to divulge names of so-called subversives to the House Committee on Un-American Activities. Scientists are being persecuted today, in China and Iran and elsewhere, but science lives on wherever people are willing to tolerate uncertainty, to admit how little they know, and to learn.
Science has evolved along two consilient paths, the Baconian and the Cartesian, named after Francis Bacon and René Descartes. Bacon stressed induction, an approach that starts with observation and adduces hypotheses from them: “All depends on keeping the eye steadily fixed on the facts of nature, and so receiving their images as they are,” he wrote, “for God forbid that we should give out a dream of our own imagination for a pattern of the world.” Descartes stressed deduction, reasoning from first principles and rejecting any precept about which he could conjure any doubt. “I showed what the laws of nature were,” he claimed, “and without basing my arguments on any principle other than the infinite perfections of God, I tried to demonstrate all those laws about which we could have any doubt, and to show that they are such that, even if God created many worlds, there could not be any in which they failed to be observed.”
It is tempting to associate induction and deduction with experimental and theoretical science respectively, although either without the other would be the sound of one hand clapping. Politically, it is said that the legacy of (mostly British) induction fostered liberalism, while (mostly French) deduction promoted socialism. Be that as it may, Bacon is a good place to start.
Bacon is often called the prophet of the scientific revolution, an apt title in that prophets make predictions by methods unknown even to themselves. His biography is a shattered mirror in which can be read everything from the criminality of a wrecked lawyer to the integrity of a poet sufficiently talented to be credited with writing Shakespeare’s plays. Bacon moved in aristocratic circles—he was made lord chancellor in 1618, and was titled Baron Verulam—yet saw the future as meritocratic. He suffered from ill health but accomplished staggering amounts of work in law, government, literature, and philosophy. He was repelled by the Aristotelian doctrines taught at university (comparing his Cambridge professors to “becalmed ships; they never move but by the wind of other men’s breath”) but disliked disputation, saying that he came as a guest and not as an enemy. Prescient about the future rise of science, he cared little about the actual scientific research going on around him: He dismissed Copernicus’ cosmology, discounted Galileo’s telescopic discoveries, remained indifferent to William Harvey’s discovery of how blood circulates in the human body, and ranked Gilbert’s experiments with magnets little higher than the alchemists’ vain attempts to turn base metals into gold. The Marquis de Condorcet observed:
Bacon, though he possessed in a most eminent degree the genius of philosophy, did not unite with it the genius of the sciences. The methods proposed by him for the investigation of truth, consisting entirely of precepts he was unable to verify, had little or no effect in accelerating the rate of discovery…. Yet the very temerity of his errors was instrumental to the progress of human thought. He gave activity to minds which the circumspection of his rivals could not awaken from their lethargy. He called upon men to throw off the yoke of authority, and to acknowledge no dogma but what reason sanctioned; and his call was obeyed by a multitude of followers, encouraged by the boldness and fascinated by the enthusiasm of their leader.
For all his limitations, Bacon foresaw that science would transform not only knowledge but politics, economics, and society. “I have held up a light in the obscurity of philosophy which will be seen centuries after I am dead,” he wrote.
It will be seen amidst the erection of temples, tombs, palaces, theaters, bridges, making noble roads, cutting canals, granting multitudes of charters and liberties…in the foundation of colleges and lectures for learning and the education of youth; foundations and institutions of orders and fraternities for nobility, enterprise, and obedience; but above all, the establishing [of] good laws…and as an example to the world.
And so it did.
When Bacon studied philosophy at Trinity College, Cambridge, he found the teachers underpaid, excessively devoted to sterile exercises in logic and rhetoric, ill equipped to conduct scientific experiments and demonstrations, “shut up in the cells of a few authors, chiefly Aristotle their dictator,” insufficiently rewarded “for inquiries in new and unlabored parts of learning,” and therefore apt to “spin cobwebs of learning, admirable for the fineness of thread and work, but of no substance or profit.” “In the universities, all things are found opposite to the advancement of the sciences,” he wrote. He came away impressed by the sheer enormity of human ignorance. To assuage it, a process that he compared to diverting fresh spring water into a stagnant swamp, Bacon argued for a new method of learning based on observation, experiment, and inductive reasoning.
Formal scholarship in Bacon’s day consisted mainly of theology and philosophy. Both looked backward—theology to the sacred texts of old, philosophy to the Greeks and Romans—and saw the present as a pale shadow of past glories. It was evident that Europe had no philosophers comparable to Plato and Aristotle, while for theologians humankind had abided in sin since Adam and Eve were expelled from the Garden of Eden. Neither camp saw much reason to study nature. Bacon accused his philosophy professors of teaching that the ancients knew things they never actually knew, thus producing students who in turn thought that they knew things they did not know. The theologians, especially those rooted in Pauline and Augustinian thought, regarded nature as depraved. In their view the purpose of life, as a modern scholar puts it, was “to escape upwards from this Satan-ridden earth…beyond the planetary spheres with their disastrous influences, into the divine empyrean.”
Bacon stood this hierarchy on its head. He judged the ancient Greeks to be worthy within their limits, but far too preoccupied with logical formalities—what he called “the ostentation of dispute”—to be of much use in comprehending how nature works. “The sciences we possess have been principally derived from the Greeks,” he writes, “but the wisdom of the Greeks was professional and disputatious, and thus most adverse to the investigation of truth.” A legendary Egyptian priest had described the Greeks as childlike. Bacon: “They certainly have this in common with children, that they are prone to talking, and incapable of generation, their wisdom being loquacious and unproductive of effects. Hence the external signs derived from the origin and birthplace of our present philosophy are not favorable.” Far from being eternally indebted to the Greeks, we are hobbled by our devotion to them: “The reverence for antiquity, and the authority of men who have been esteemed great in philosophy, and general unanimity, have retarded men from advancing in science, and almost enchanted them.” Books should follow science, not science books, if “the discovery of things is to be taken from the light of nature, not recovered from the shadows of antiquity.”
“Our only hope,” Bacon asserted, “is in genuine induction”—the building up, from observations and experiments, through “progressive stages of certainty” to larger conclusions. Induction is quite distinct from the deductive logic of syllogisms:
The difference between it and the ordinary logic is great, indeed immense…. Hitherto the proceeding has been to fly at once from the sense and particulars [that is, sense perceptions] up to the most general propositions, as certain fixed poles for the argument to turn upon, and from these to derive the rest by middle terms: a short way, no doubt, but precipitate, and one which will never lead to nature, though it offers an easy and ready way to disputation.
If instead you work patiently upward from observations, the most general propositions “are not reached till the last, but then when you do come to them, you find them to be not empty notions but well defined, and such as nature would really recognize as her first principles, and such as lie at the heart and marrow of things.” Bacon’s induction might look grubbily workmanlike when compared to the “pure reasoning” of the scholastics, but it promised to bring human ideas about the material world into closer concordance with that world, to aid in “cultivating a just and legitimate familiarity between the mind and things.”
Those of us who live in today’s liberal-scientific societies may find it difficult to appreciate just how odd Bacon’s arguments must have seemed to his contemporaries. The material world was with them all right—they heard it and smelled it and scraped it off their boots at the door upon arriving home—but was hardly a fit subject for study. The material world was where your workday lasted twelve hours in winter and fourteen hours in the summer, where half of your children died before reaching age thirty, where a grinning highwayman would murder you for your clothes on a road adorned with the rotting corpses of his hanged colleagues, and where the plague could kill a fifth of all Londoners in a single year. A Venetian visitor reported that England’s greatest city was covered by “a sort of soft and stinking mud which abounds here at all seasons, so that the place more deserves to be called Lorda [filthy] than Londra [London].” Drunken lorry drivers fought openly in streets with such frankly descriptive names as Stinking Lane, one Thomas Dekker observing in 1606 that
in every street, carts and coaches make such a thundering as if the world ran upon wheels: at every corner, men, women, and children meet in such shoals, that posts are set up of purpose to strengthen the houses, lest with jostling one another they should shoulder them down.
Criminals were so abundant that new words were coined to describe their enterprises: Priggers stole horses, nips sliced open purses on the streets, curbers hooked clothes they found hanging out to dry. Public executions, conducted by axe-wielding killers wearing white butcher’s aprons to show off the blood, were reliably popular amusements. The common people were so xenophobic that foreigners risked being spit on or beaten if they dared venture forth wearing their native attire; Jews were banished from England altogether for 365 years before being admitted by Cromwell in 1655. The majority of English subjects were illiterate and poor and so had no voice in history, but when the journalist Henry Mayhew began interviewing them in the 1800s he recorded testimonies like this one, from a middle-aged woman:
I don’t think much of my way of life. You folks as has honor, and character, and feelings, and such, can’t understand how all that’s been beaten out of people like me. I don’t feel. I’m used to it…. Idon’t want to live, and yet I don’t care enough about dying to make away with myself. I aren’t got that amount of feeling that some has, and that’s where it is.
One did not willingly embrace this world. If possible one escaped from it, into the university and the Church. (The two were closely linked, since, as Joseph Priestley noted, “None but the clergy were thought to have any occasion for learning.”) It was the genius of Francis Bacon to foresee that this would not always be the case.
Bacon’s vision of the future, although necessarily imprecise, arose from a realization that scientific knowledge—combined with better tools and techniques that he called “instruments and helps”—could elevate the human condition to unimaginable heights. “Neither the naked hand nor the understanding left to itself can effect much,” he wrote. “It is by instruments and helps that the work is done, which are as much wanted for the understanding as for the hand. And as the instruments of the hand either give motion or guide it, so the instruments of the mind supply either suggestions for the understanding or cautions.” In Bacon’s day it was assumed that anyone out to control nature must subdue it, much as a militia might subdue a riot, by pitting power against power. Bacon saw that the key was not force but comprehension (“Nature to be commanded must be obeyed”), and that knowledge would bring dominion over nature: “Knowledge itself is power.”
Bacon’s unfinished novel New Atlantis hinted at a forthcoming age of ingenuity. The Atlantans boast of having refrigerators, “new artificial metals,” desalinization plants, air purifiers, agriculturally engineered fruit “greater and sweeter, and of differing taste” than those found in nature, experimental zoological parks where they “make a number of kinds of serpents, worms, flies, [and] fishes,” beverages that last unspoiled for decades, sophisticated pharmaceuticals, “perspective houses, where we make demonstrations of all lights and radiations and of all colors,” advanced telescopes and microscopes, synthetic magnets and crystals, “sound houses” where “the voices and notes of beasts and birds” are mechanically produced, “trunks and pipes” that act as telephones, “engine houses, where…we imitate and practice to make swifter motions than any of you have,” flying machines and submarines, and a kind of cinema “where we represent all manner of feats of juggling, false apparitions, impostures and illusions.”
Bacon was fond of material things (“He wrote like a philosopher and lived like a prince”), a predilection that may have contributed to his dismissal as lord chancellor on charges of accepting bribes. Such reversals did little to blunt his influence in the centuries that followed. Black magic, based on the erroneous assumption that nature could be commanded by casting spells without understanding how or why they worked, devolved from a fearsome instrument of satanic power to a set of magician’s props. The Royal Society was founded “to provide instruction to sailors and merchants in useful arts, especially practical mathematical techniques.” Machinists, metallurgists, navigators, and chemists inched upward in social status, and the old world of lifelong class distinctions began to slip its moorings.
Bacon was the prophet of the liberal-scientific world, not its practitioner. He condemned superstition but credited reports of miracles, thinking it self-evident that “all knowledge is to be limited by religion.” He envisioned future societies dedicated to peace and progress, yet displayed little enthusiasm for political reform. Voltaire said that Bacon “did not yet understand nature, but he knew and pointed out the roads leading to it,” building “the scaffold with which the new philosophy was raised; and when the edifice was built, part of it at least, the scaffold was no longer of service.” The poet Abraham Cowley wrote that
Bacon, like Moses, led us forth at last
The barren Wilderness he past,
Did on the very Border stand
Of the blest promis’d Land,
And from the Mountains Top of his Exalted Wit,
Saw it himself, and shewed us it.
Bacon said as much himself: “I have only taken upon me to ring a bell to call other wits together.”
Meanwhile René Descartes, a generation younger than Bacon, was working the other side of the street, attempting to rebuild philosophy through pure deduction. Born near Tours into a reputable family—his father was a member of Parliament—Descartes was a hothouse flower who suffered from debilitating respiratory ailments. As a boy he was permitted to linger in bed for as long as he liked in the mornings, a habit that his fellow mathematician Blaise Pascal thought ideal for mathematical reasoning. He had an aversion to cold, overheating his living quarters so much that he called them “stoves.” (Many modern readers are confused by this reference, but the residents of dank seventeenth-century homes often slept close to their stoves or even on top of them.) Educated in the Jesuit college of La Fleche, an experience that he always recalled with respect and delight, Descartes enlisted in the Dutch army of Maurice of Nassau—an odd choice for a sickly young man, but one that befit his family’s tradition of military valor and afforded him ample time to think. While dreaming one night in his “stove,” Descartes had a vision of a unified system of knowledge based solely on reason. Recognizing that such ideas would be viewed with hostility by the clergy, he moved in 1628 to the Dutch Republic, Europe’s freest and most tolerant state, where he remained for twenty years. Even there he found it imprudent to publish his first book, Le Monde, which advocated the Copernican cosmology. (It was completed in 1633, just as Galileo was being punished by the Inquisition for taking the same position.) In September 1649, under attack for his alleged blasphemies, Descartes boarded a Swedish warship and departed for Stockholm.
He was responding to an invitation to tutor Queen Christina of Sweden, a young scholar of insatiable intellectual appetites. (Still in her twenties, she had already written two treatises on ethics and established Sweden’s first newspaper. In later years she would abdicate the throne and move to Rome, where she built an astronomical observatory and underwrote the construction of Rome’s first opera house.) Kristina took her learning seriously, requiring that the two meet at 5 a.m. for classes lasting four to five hours. The deepening Swedish winter afflicted Descartes, who by January was complaining of being “out of his element” in cold so severe that “men’s thoughts are frozen here, like the water.” He contracted pneumonia, and died on February 11, 1650, aged fifty-four.
As John Stuart Mill remarked, Descartes had a “purely mathematical type of mind.” This was the strength of his many contributions—such as the Cartesian coordinate system, which scientists have used ever since—but also their liability, in that Descartes thought of science as completely deducible from mathematics. “The only principles which I accept, or require, in physics are those of geometry and pure mathematics,” he wrote. “Those principles explain all natural phenomena.”
Well, yes and no. Science has since demonstrated that all phenomena can be described mathematically, but while some mathematics is scientifically applicable to the observed world, much of it is not. We do not, for instance, live in a world of ten, rather than three, spatial dimensions—unless, as string theory posits, the higher dimensions exist but are for some reason imperceptible. The trick is to find which mathematical tools apply to which aspects of the observable universe, a matter more often determined by observation and experiment than by deductive reasoning. Some theories survive experimental testing, but all are colored by a tincture of doubt. Even when a theory makes exquisitely accurate predictions (as does, say, quantum electrodynamics), a better one may come along that takes in a wider range of phenomena—which is why scientists today are trying to find a unified account of electrodynamics and gravitation. Because Descartes did not see this, his conception of science was in some ways sterile; it could explain things but predict next to nothing.
A man of considerable charm, Descartes in his Discourse on Method makes the egalitarian claim that “good sense is of all things in the world the most equally distributed,” adding, “I have never ventured to presume that my mind was in any way more perfect than that of the ordinary man.” He modestly recounts “the increasing discovery of my own ignorance,” going on to note, with robust skepticism, that “there is nothing imaginable so strange or so little credible that it has not been maintained by one philosopher or other.” All quite modern, that, but the book remains almost entirely confined within Descartes’ ample but solitary skull. Exhibiting little of the collegiality that would come to characterize the scientific community, it resembles the lone lamp of a solitary ship, searching dark oceans for an unassailable truth. In this sense Descartes belongs among the ancients, confined by what Bernard Williams of Oxford calls his “preoccupation with the indubitable.”
Beneath the beacons of brilliant philosophers like Bacon and Descartes toiled budding scientists like the decidedly unphilosophical Irish chemist Robert Boyle. Born into a titled family (his tombstone bears the epitaph, “Father of Chemistry and Uncle of the Earl of Cork”), Boyle put Bacon’s dicta into action although he acknowledged neither Bacon nor anyone else as a teacher, preferring to stress that his learning was adduced directly from nature. Boyle was well rounded (he fenced and played tennis at Eton), and well traveled (he visited Switzerland, Holland, and France, and was in Florence when Galileo died there), but was happiest in his laboratory. Working at Oxford with Robert Hooke (who did pioneering work in microscopy and coined the biological term cell), Boyle invented an air pump and demonstrated that charcoal and sulfur would burn only in the presence of air. (Nor, he learned, can mice or kittens survive in an airless environment, although he was too tenderhearted to persist with such experiments.) This was an important step toward the discovery by Joseph Priestley in 1774 of the component of air that supports combustion, which Antoine Lavoisier named oxygen. Boyle also established what has been known ever since as Boyle’s law—that at a constant temperature, the volume of a given mass of air or any other gas varies inversely with its pressure—and he measured the density of air, using an instrument he named the barometer. Ceaselessly inventive, Boyle built a portable camera obscura that focused images on a piece of translucent paper, developed a hydrometer to measure the densities of liquids, and fashioned the first match, from heavy paper and phosphorus.
Boyle gave short shrift to any notion that did not emerge from experimental evidence or at least answer to it. Descartes had denied the possibility of a vacuum, preferring to view space as pervaded by an ether. Boyle found that the sound of a rung bell would not propagate through an evacuated chamber, indicating that there was nothing left in the chamber to carry the sound, so he dismissed ether as superfluous. Like Descartes, he saw the world as composed of matter and motion; unlike Descartes, he never let such conceptions take him very far from the laboratory. His contemporaries regarded him as perhaps the first true scientist among them, so much so that the empirical, mechanistic, and decidedly nonmystical world view that ascended with the Enlightenment was often referred to, in England at least, as the work “of Newton and Boyle.”
Newton’s Principia drew the disparate threads of Renaissance science together into a quantitative theory of gravitation that made accurate predictions of the motions of planets and comets in the sky. Copernicus had suggested that the earth orbits the sun; Newton calculated that the sun’s gravitational force holds the earth in its orbit by counteracting the inertia that would otherwise send us careening off into space. Kepler’s study of Tycho Brahe’s astronomical observations had revealed that the orbits of the planets are ellipses rather than circles; Newton demonstrated mathematically why this must be so. The planets have gravity, too; hence their orbits cannot be perfect circles, which have but a single “focus” at their centers, but must be ellipses, the two foci representing the fact that two gravitating objects are involved. Galileo had inferred from pendulums and rolling-ball experiments that were it not for air resistance, all bodies would fall at the same rate; Newton proved that the planets’ orbital velocities are determined by their distance from the sun, not by their mass: A pebble in the orbit of Saturn moves at the same velocity as does mighty Saturn itself. Bacon and Boyle had championed experimentation; Newton experimented constantly with chemistry, metallurgy, and optics, inventing and building a new sort of telescope that remains the world’s most popular today. Descartes (whom the young Newton studied closely) had stressed mathematical analysis; Newton invented the calculus in order to do the analysis required to complete his Principia, the full title of which was Mathematical Principles of Natural Philosophy. That one book buried the Ptolemaic cosmology, demonstrated that the solar system works according to mathematically precise rules, showed that these same rules apply on earth as in the heavens, and provided the world with a handbook useful in calculating a million practical matters, from the strength of bridge girders to the amount of rocket fuel required to dispatch astronauts to the moon.
Newton also set an example by acknowledging what he did not know. He volunteered that he did not know, for instance, what gravity was, or how it could propagate through empty space. “I have explained the phenomena of the heavens and of [the tides] by the force of gravity,” he wrote, “but I have not yet assigned a cause to gravity…[as] I have not yet been able to deduce from phenomena the reason for [its] properties.” (That would remain for Einstein to solve.) Echoing Boyle’s sentiment that it is better to establish part of the truth than to pretend to know it all, Newton wrote that “although the whole of philosophy is not immediately evident, still it is better to add something to our knowledge day by day than to fill up men’s minds in advance with the preconceptions of hypotheses.” By “hypotheses” Newton meant different things at different times (one scholar has counted nine Newtonian definitions of the word), but his point here was to distinguish the scientific method from that of philosophers like Descartes, who thought he could build an entire universe from a single, allegedly indubitable, hypothesis. In that sense, Newton’s famous hypotheses non fingo—“I do not fabricate hypotheses”—is very nearly the opposite of Descartes’ cogito ergo sum.
Stylistically severe, crammed with mathematics, and written in Latin rather than the vernacular, the Principia is a forbidding work. How is it, asks the historian of science I. Bernard Cohen, “that a largely unintelligible book—its pages closed to all but the most skilled and dedicated mathematicians—would dominate the intellectual character of the Enlightenment and become the most generally influential work of its age”? One answer is that it gave traction to the scientific enterprise, by combining many experiments and observations into a unified mathematical account of gravitation, which along with light constituted the only two forces known at that time. (Discovery of the strong and weak nuclear forces was the work of twentieth-century physicists.) Newton dropped the other shoe with his Optics, published in 1704, a work brimming with experiments so edifying that students still perform them today. These two books reinforced both avenues of scientific research—one primarily mathematical, like the Principia, and the other, arising from the Optics, stressing experiment. The historian Hunter Crowther-Heyck describes Newton “as a conqueror rather than a rebel; if Galileo is the Scientific Revolution’s Tom Paine, Newton is Jefferson and Washington rolled into one.” The result was the Enlightenment, and the democratic revolution.