NO ONE REMEMBERS a German spectacle-maker named Hans Lipperhey.

In December 1608, Lipperhey received disappointing news: the Dutch had rejected his application for an exclusive patent for a spyglass. It was rejected not because his instrument failed to meet expectations — indeed, the spyglass had been successfully tested many times since Lipperhey arrived in The Hague three months earlier, seeking a reward for his marvelous invention. Each time, it reliably magnified distant objects: the spire of a distant cathedral, the bell tower in another town, the arrival of ships barely on the horizon, perhaps even the approach of an army. In fact, everyone was talking about the spyglass and eager to acquire one. News traveled even faster than the instrument, making it the most discussed piece of technology in the first decade of a new century. Curiously, seeing just a little bit farther sufficed for most consumers of this newfangled gadget. A growing number of would-be inventors therefore rushed competing versions of this latest Renaissance gizmo to the marketplace. They churned out spyglasses of varying quality, priced to appeal to a wide range of consumers, with little regard to perfecting what this instrument actually did. Therein lay the problem: the spyglass was too easy to make.

As a consolation prize, the Dutch commissioned two more examples from Lipperhey. Had he not died shortly after fulfilling the order, on September 29, 1609, our German spectacle-maker might well have developed a modestly successful business selling his spyglass. Instead, from the grave as it were, he suffered the ignominy of having his invention named after the very people who denied him a patent — it became the “Dutch spyglass.”

At the end of Lipperhey’s life, a similar demonstration of another spyglass took place in Venice, with very different results. In late September 1609, a middle-aged mathematics professor named Galileo Galilei, a native of Tuscany but long employed by the Venetian Republic to teach at the University of Padua, persuaded Venice’s leading citizens to do what tourists have done ever since: huff and puff their way to the top of the campanile in piazza San Marco to gaze across the city, its lagoon, and mainland territories. In this instance, however, the object was not simply to marvel at the magnificence of La Serenissima, but to see what Galileo’s new sighting instrument revealed. This instrument, called an “eyeglass,” “long-sighted cannon,” or the Latin perspecillum rather than a “spyglass,” would not be called a “telescope” until 1611.

Unlike the cautious Dutch stadtholders, the Venetians handsomely rewarded their inventor. Galileo became one of their highest paid professors, with lifetime job security. Venice, a city of enterprise and innovation, was just the right location to produce a powerfully modern instrument. Famed for its Murano glass and the skill of its artisans, and offering favorable conditions to talented immigrants, Venice had long encouraged inventors to register their secrets with the state. The Venetians immediately requested 16 more examples of the new instrument, enjoining Galileo not to divulge to others the details of its production. Galileo became an international celebrity with the publication of his Sidereal Messenger in March 1610 — a slim pamphlet dramatically illustrating the surprisingly earthlike features of the moon, as well as numerous previously unrecorded stars, and his startling discovery of Jupiter’s four satellites. There were novelties in the heavens that only Galileo’s occhiale seemed to reveal. Soon, everyone knew Galileo by name, and associated him with the most transformative invention of his century.

Between Lipperhey’s failure and Galileo’s success lies a rich and complex story of how the Galilean telescope emerged from the Dutch spyglass. In Galileo’s Telescope, Massimo Bucciantini, Michele Camerota, and Franco Giudice — three distinguished historians of science who have written extensively on Galileo — retell this famous story in light of considerable new evidence and their own firm grasp of the twists and turns of [its] history. Fundamentally, they remind us that we need to stop looking only at Galileo. Seeing Galileo from his own perspective is rather like looking just once through his telescope, whose limited field of vision revealed no more than about one-quarter of the moon. In order to understand the constellation of events that shaped this new instrument, we need to view it from multiple perspectives, following its scientific itinerary while also observing how it appeared in painting, poetry, plays, and politics. Surveying the entire European landscape in the years immediately before and after Galileo’s announcement, this book offers a comprehensive vision of how an entire world, rather than a single if singular individual, gave birth to the telescope.


At the beginning of the 16th century, Leonardo da Vinci jotted a note to himself about how wonderful it would be to magnify the moon. This dream became a reality in Galileo’s age. I happened to finish Galileo’s Telescope during a summer trip to the northern Nevada desert, one of the most harshly beautiful corners of the western states. Sleeping outdoors at high elevation with almost no ambient light to cloud our vision, my husband, daughter, and I counted the meteors. Many constellations were visible and one could easily see the Milky Way, Orion’s Belt, perhaps even the Pleiades. We brought astronomical binoculars that magnified about as well as the telescope Galileo presented to the Venetian doge — in fact better, because Galileo’s spyglass showed less, and upside down. It initially dimmed rather than brightened his view and shook if not properly stabilized; any imperfections in the lenses detracted from its clarity. Nowadays, with a fairly ordinary pair of binoculars, you can see a great deal with little training or effort. I found myself thinking about precisely how Galileo’s world realized its technological advantage by cultivating the patience to endure these difficult, often frustrating first encounters with a rough-hewn instrument. The traditional tools of astronomy directed one’s sight and assisted in calculating distance, but the telescope expanded one’s field of vision. This was the first generation whose mind took flight with the aid of an instrument. The German astronomer Johannes Kepler would endlessly rewrite a book called The Dream, which many considered to be the first work of science fiction. More than anyone, he understood how science is fueled by and, in turn, inspires the imagination. Galileo instead realized the value of a really fine instrument.

How did people, including Galileo, hear of the spyglass? What did they do with this news? Galileo’s Telescope peeks inside diplomatic pouches and monitors the flow of private letters, missionary correspondence, and public reports that conveyed news and rumor. We turn over Renaissance envelopes to discover Galileo’s hastily scribbled shopping lists for ingredients to make better lenses, or his quick sketch of an exciting discovery. The result is a lively, informative, and thought-provoking narrative that takes us on an epic journey that begins in Northern Europe, migrates to the Venetian Republic, heads east to Prague, and veers north to England and France. Only then do we return to the most Catholic parts of Italy, not yet conquered by the telescope, culminating in a pilgrimage to Rome. Ultimately the telescope’s journey ends in India and China, with the Jesuit astronomers who separated the instrument from the man whom their church tried and condemned in 1633 for advocating Copernican astronomy.

It has often been said that Galileo never saw the Dutch spyglass. Relying only on its description, he retreated into his workshop and emerged with an optical device capable of transforming astronomy. This is precisely what Galileo wanted us to think. Bucciantini, Camerota, and Giudice dismantle this narrative. They pay close attention to how news of the Dutch spyglass arrived in the Venetian Republic and they ask who most eagerly solicited this information. Galileo’s controversial friend, the Servite friar Paolo Sarpi, did.

Sarpi considered the Dutch spyglass useless. Venice’s state theologian, Sarpi was best known for his trenchant criticisms of the papacy. He was already a larger than life figure when Galileo was still boarding students and teaching overtime to supplement his modest professorial salary. A talented mathematician and natural philosopher passionately interested in optics, Sarpi read about lenses and tested the properties of glass, crystal, and mirrors long before meeting Galileo. He conferred with the Neapolitan magus Giambattista della Porta, whose bestselling Natural Magic suggested that it was possible to make lenses to see beyond imagination. Della Porta was not alone in praising Sarpi as one of the great scientific minds of the age. Far more cosmopolitan and connected than Galileo, Sarpi already enjoyed an international reputation before 1609. His brave political and theological stance against the papal authority earned him the admiration of Protestants and freethinking Catholics alike, and infamously inspired a botched assassination attempt by papal henchmen in October 1607. Why have we largely ignored Sarpi’s role in the making of the telescope?

Sarpi published none of his optical work and most of his papers perished in a 1769 fire. It takes patient detective work to reconstruct his scientific activities. For political and religious reasons, he was accustomed to concealing more than he revealed. By contrast, Galileo openly embraced the publicity that came with spectacular results, throwing caution to the wind when he felt he had gained the upper hand. Sarpi felt that his friend was playing a dangerous game. He wisely anticipated that the Roman Catholic Church would not be ready to overturn traditional cosmology simply because a brash astronomer told them that the world changed when viewed from a different perspective.

Bucciantini, Camerota, and Giudice develop a compelling portrait of the Sarpi circle, which included Galileo’s great friend Gianfrancesco Sagredo (later immortalized as the fictional moderator of Galileo’s Dialogue of 1632) and Agostino Da Mula (even more obscure than Lipperhey, though many said that he, not Galileo, was the first to spy the famous Jovian “moons”). Sarpi used his extensive political network to collect news of the spyglass; he was frequently seen with Galileo, discussing technical problems, identifying the best artisans and materials, and observing the heavens. While Galileo perfected his lens grinding and polishing, Sarpi mobilized the Venetian political machine to carefully orchestrate Galileo’s success. In the end, we will never know how much of the skill required to transform an easily replicable spyglass into a finely engineered and truly unique telescope belonged to Galileo, but his collaboration with the heterodox Sarpi circle was certainly an essential component. Even after Galileo left Venice, members of the Sarpi circle continued to observe the heavens and sought to improve their theoretical understanding of the telescope.

This was Sarpi’s project, but was it Galileo’s? Galileo’s Telescope argues that the Sidereal Messenger makes manifest Galileo’s betrayal of Sarpi. A pamphlet filled with sycophantic praise for Galileo’s Tuscan patrons, after whom he named the four “Medicean stars” orbiting Jupiter, it contained not one word about the role of the Venetians in making these spectacular discoveries possible. When Sarpi told a mutual friend, eager to acquire the book everyone was talking about, that he had not read it, he was expressing his disappointment at Galileo’s ingratitude, and his frustration with Galileo’s calculated decision to move to Florence, home to a more conservative state with close ties to papal Rome. If Galileo was the carefully chosen front man for Project Sarpi, he ultimately turned out to be a kind of double agent, willing to abandon Venice in his eagerness to pursue his own agenda.

After March 1610, the telescope took on a life of its own, precisely because it was so prominently in the news. How Galileo communicated his discoveries, found his advocates, and combatted his critics are all part of the telescope’s history, but Galileo’s Telescope is equally concerned with how other people responded to Galileo’s telescope and to his claims for what it revealed. What did it inspire them to do?

In Prague, Kepler was so eager to support Galileo’s findings that he rushed some hasty comments into print in May 1610, even before he was able to confirm Galileo’s claims empirically. Galileo never sent him a telescope, and Kepler failed to build one that magnified as well. Yet Kepler’s published descriptions of Galileo’s discoveries, including a preview of observations regarding the phases of Venus and the strangely oblong shape of Saturn that Galileo shared with Kepler in playful anagrams to bedazzle emperor Rudolph II, famously known for his love of alchemical secrets and occult mysteries, gave Protestant readers the most detailed account of what one might see with this new instrument. The religious and political fault lines of a world shaped by the Reformation played an important role in determining how information about the telescope traveled.

Galileo was not the only mathematician busy making a new instrument. Just outside of London, Kepler’s correspondent Thomas Harriot, best known for his 1590 description of the new land of Virginia illustrated by John White, made a “perspective cylinder” that magnified 6x after hearing about the Dutch spyglass. In July 1609, Harriot observed and drew the moon, anticipating Galileo by two or three months, though his early drawings appeared more like cartographic maps outlining a surface rather than the shaded perspectival drawings of lunar mountains, valleys, and craters that Galileo’s artistic training enabled. A year later, Harriot read Galileo’s Sidereal Messenger and rushed to the Tower of London to describe its contents to two distinguished prisoners, Sir Walter Raleigh and his patron, the Earl of Northumberland. Harriot and his principal collaborator Sir William Lower began to replicate Galileo’s observations, comparing their drawings to his images. Envisioning the next steps toward a new astronomy, they calculated the periodicity of Jupiter’s satellites, unaware that Galileo was doing similar work for an enlarged edition of the Sidereal Messenger that he promised his public but never produced.

Ultimately, Harriot did not publish his observations. Perhaps he recognized that the English perspective cylinder was not as good as the Venetian long-sighted cannon? He also lacked the necessary support to bring his work to fruition: with the disintegration of their relations with James I, his entire Northumberland circle was in the midst of an unfolding political disaster. Bucciantini, Camerota, and Giudice elegantly read John Donne’s 1611 lament about the unsettling effects of the new astronomy as a strategic effort by the English poet to distance himself from the problematic position of his friend the Earl, in whose library Donne first encountered Galileo’s work. The tantalizingly incomplete nature of Harriot’s astronomy is a reminder that many ingredients need to coalesce for interesting research to earn public acclaim. Even Galileo seems to have been unaware of Harriot.

Neither Kepler nor Harriot successfully replicated Galileo’s instrument, which ultimately magnified about 30x. Instead, the Aix lawyer Nicolas-Claude Fabri de Peiresc boasted that the lunette he developed in September 1611 magnified an unbelievable 400x! He also replicated Galileo’s observations, produced his own tables of the Jovian moons, and felt he was on the verge of solving the mystery of Saturn’s peculiar bulges. Closely connected to the Venetian Republic, Peiresc knew about Galileo’s volte-face, attributing his actions to Tuscan shrewdness. He aspired to outdo Galileo by dedicating his own discoveries to the French queen Marie de’ Medici, long interested in optical devices. Galileo gave her two telescopes, the second designed to curb her disappointment with the first. Like Harriot, Peiresc did not publish, though not for lack of opportunity. He was a savvy broker of knowledge and famously reluctant to subject his work to criticism. In the end, overcoming his distaste for how Galileo, a product of Machiavellian Florence, treated their Venetian friends, he offered him his data.

In his Sidereal Messenger, Galileo made difficult collaborative work look like the effortless result of a lone astronomer. Galileo’s Telescope reminds us of just how difficult it was to see the new heavens. It took time, patience, and skill to use the telescope well, and even Galileo acknowledged that only a handful of his telescopes had lenses capable of revealing everything he reported. This was truly a technology-in-the-making, and it often failed. Some critics concluded that it was a kind of magic lantern, generating its own images. Cautious minds needed firmer proof.

Bucciantini, Camerota, and Giudice rightfully argue that Galileo’s goal, in leaving Venice behind and barely acknowledging his talented Protestant colleagues in Northern Europe, was to conquer Catholic Europe. The most elegant copies of his book and the best versions of his instrument were reserved for Catholic rulers and prelates. In 1610–’11, Galileo made two strategic trips to the two primary cities of the Papal States, first Bologna and then Rome, to gain allies. It was there, as well as in his native Florence, that he began to encounter problems that would eventually lead to his trial and condemnation.

In April 1610, a group of experts in Bologna failed to see much of anything through his telescope. News of this disappointing result traveled widely. Bucciantini, Camerota, and Giudice persuasively recount how Galileo’s failure in Bologna fueled rumblings in Florence among the members of a rump group, suspicious of the astronomer and his instrument. As late as October 1610, the Jesuit astronomer Christopher Clavius and his disciples at the Roman College had yet to confirm his findings. Galileo’s Venetian friends resurfaced, warning him to tread lightly. Instead, Galileo told the venerable Clavius that his latest discoveries negated two millennia of traditional cosmology. One year after his Bolognese humiliation, he was determined to succeed in Rome.

It is all too easy to see Galileo’s trip to Rome in spring 1611 as an unqualified triumph. Clavius confirmed virtually all of Galileo’s observations, though he was unwilling to agree with him about their cosmological implications. The telescope had triumphed, but what about Galileo? He went to every party in town, made new and influential friends, and joined a prestigious scientific academy. Paul V commissioned Galileo’s friend, the painter Ludovico Cigoli, to depict a Galilean moon in the Borghese chapel in Santa Maria Maggiore, though this did not necessarily make the pope a Galilean. Galileo’s admirers proclaimed that the ancient Romans would have erected a statue in his honor on the Capitoline.

Galileo’s most loyal Venetian friends reminded him that he was playing with fire. In May 1611, two weeks before his return to Florence, the Roman inquisitors met privately to determine whether Galileo’s name had surfaced in depositions about another controversial Paduan scientist. They were already beginning to wonder about the orthodoxy of his science. The head of the Roman Inquisition, Cardinal Robert Bellarmine, later told the Tuscan ambassador that if Galileo had stayed longer in Rome, he would have had to talk with the inquisitors in person. The Florentine Dominicans would later recall that Galileo was a friend of Sarpi, whom they branded a heretic, or worse. Bucciantini, Camerota, and Giudice’s judicious narrative spells out how Galileo’s desire to bring his astronomy to Rome galvanized other communities to action.

The telescope inspired many different projects for rethinking the heavens. By 1612, news of this instrument traveled on Portuguese ships bound for India, where Jesuit astronomers wrote excitedly to their confrères in Rome that they had fine crystal with which to make lenses, if only they could get instructions on how to make a telescope. As reports of the telescope traversed the Indian Ocean and entered the South China Sea, they became part of the scientific conversations between European missionaries and Chinese converts. In 1615, the Portuguese Jesuit based in Beijing, Manuel Dias Jr. (known to his Chinese brethren as Yang Manuo), rushed to insert a description of Galileo’s observations, including a woodcut of the bulging shape of Saturn, in the final pages of his Chinese manual of Western astronomy. He promised his Chinese readers he would show them a telescope as soon as one arrived in the Middle Kingdom. The telescope had not yet circled the globe but would complete its voyage in the next decade or two. Young Puritans attending a new North American university called Harvard and Spanish American Criollos in the Jesuit colleges of the New World would study astronomy using a telescope by the mid-17th century. Eusebio Kino brought one with him as he mapped and evangelized Baja California. These episodes lie beyond Galileo’s Telescope, but the approach of its three authors inspires readers to transform the European journey of the telescope into a global history.

The desire to Christianize the heavens was one of the unintended outcomes of Galileo’s telescope. In one of the most fascinating chapters of their book, Bucciantini, Camerota, and Giudice explore the archbishop of Milan Federico Borromeo’s passionate engagement with the new astronomy. He acquired numerous telescopes and replicated Galileo’s observations, with the goal of writing a Christian cosmology that perfectly fused science and faith. Like the Jesuit astronomers, Borromeo divorced Galileo’s discoveries from his theory. The more loudly Galileo proclaimed the Copernican nature of the heavens, the more he encouraged learned men of faith such as Borromeo to seek alternatives. “Take inspiration from Galileo,” he wrote in a note to himself. “Examine his reasons. Refute them.”

The Borromeo circle had its own agenda, which aligned perfectly with the one that Bellarmine articulated in Rome. They wanted to use the telescope to improve their understanding of how Scripture described nature. The Catholic world that Galileo hoped to conquer thus undermined his project by taking possession of its principal instrument. In 1626 the Jesuit astronomer Johann Adam Schall von Bell, the first Westerner to head the Beijing Observatory, published an entire Chinese treatise on the telescope. After 1633, some of the best telescopes in the world were made in Rome and used inside observatories erected in the lofty domed cathedrals where Roman Catholics worshipped. They were used every bit as much in these venues as in secular temples to science such as the Greenwich Observatory. This was a result that Galileo could not have anticipated.

In 1640, Galileo’s name appeared for the first time in another book of astronomy published by Schall in Beijing. By then, “Chia-li-lé-o” was a blind, officially repentant Catholic under house arrest at his villa in Arcetri, having been forced to publicly repudiate his belief that the telescope revealed a heliocentric universe. Unlike Lipperhey, he would never be consigned to the dustbin of history. Galileo’s Telescope justly credits the nature of Galileo’s achievement and willingness to place himself at the center of an unfolding controversy, at great personal cost. At the same time, it reminds us that he was a human actor on a very large stage indeed.


Paula Findlen teaches in the History Department at Stanford University and is the author of many works on science and culture in the age of Galileo, including Possessing Nature: Museums, Collecting and Scientific Culture in Early Modern Italy.