An excerpt from

Galileo’s Instruments of Credit

Telescopes, Images, Secrecy

Mario Biagioli

From Brass Instruments to Textual Supplements

In six short years Galileo went from being a somewhat obscure mathematics professor who ran a student boarding house in Padua, to becoming a courtly star in Florence in the wake of his telescopic discoveries, to receiving a dangerous censure from the Inquisition for his support of Copernicanism. Galileo’s tactics shifted as rapidly and dramatically as his circumstances. The fast pace of these changes (often measurable in weeks or months rather than years) required him to respond swiftly to the opportunities and risks posed by unforeseen inventions and discoveries and to his opponents’ interventions.

The changing predicaments of Galileo as an author are the main focus of this book. I look at the various ways in which he disseminated his knowledge claims and instruments, but also at his secretive practices. I trace how the very meaning of credit changed as Galileo traversed different reward systems, ending with the controversy with the Inquisition, where his claims became associated not with credit but with responsibility—criminal responsibility. Galileo’s “instruments of credit” refers not only to instruments like the geometrical compass sold and gave lessons on in Padua or the telescope through which he made so many discoveries, but also to the techniques he used to maximize the credit he could receive from readers, students, employers, and patrons. I mean, for instance, the apparatus to make printable pictures out of telescopic observations, his systematic withholding of instrument-making techniques to establish a monopoly over telescopic astronomy, the bootstrapping techniques for constructing an authoritative persona, the new kinds of pictorial narratives he developed to gain assent for his discoveries, and the astute grafting of his theological arguments onto those of the theologians themselves.

While obviously connected to the claims they helped to establish, these techniques were not reducible to them any more than the telescope could be conflated with the satellites of Jupiter. Galileo’s instruments of credit were as innovative as the discoveries they helped constitute and disseminate. Their deployment did not reflect long-term commitments like, say, the establishment of a community of instrument users or of like-minded natural philosophers. If Galileo had a plan at this time, it was mostly about Galileo. The set of conventions, values, and styles he adopted and rearranged while crafting his instruments of credit did not amount to a “form of life” but to bricolages of bits and pieces of practices he was familiar with and could use at a specific time, in relation to a specific problem or opportunity. He did not have literary technologies, only literary tactics—secrecy being one of them. My analysis of Galileo’s instruments of credit is as local as the circumstances of their deployment: I wish to convey the quick pace of these moves and the pressure under which they were played rather than seek an overarching pattern that may (or may not) comprehend them.

The diversity of the economies (institutional, cultural, and legal) in which Galileo’s work was rewarded or censured easily matches (and probably exceeds) the variety of its topics and genres. These economies framed his work as well as the various modalities of its presentation, diffusion, crediting, or condemnation. He started out as a mathematics teacher (rewarded for what we would now call “work for hire”), moved up into the courtly culture of wonder and alleged disinterestedness (but also into the economy of print and authorship), and ended his life condemned to house arrest by the Inquisition for having trespassed into a restricted discursive regime (and the jurisdiction of the institution in charge of it). But if that was the end of Galileo’s career and life, it was by no means the death of Galileo-the-author. The condemnation ended up canonizing him as an Author, turning a punishment into posthumous credit. Although he could not enjoy it, the cultural capital that accrued around his image fostered what is aptly called the “Galileo Industry”—yet another economy inhabited by his work.

The twists and turns that I trace in Galileo’s career are not instances of what we call professional mobility. He was not a science Ph.D. crossing over from academia into the private sector, or a physician moving back and forth between the worlds of clinical care and medical research. As Galileo was constructing new instruments and claims, he was also constructing the economy in which his claims could be credited. The “Medicean Stars”—what we call the satellites of Jupiter—were not discoveries in the modern sense of the term. Galileo construed them as a kind of object that, while displaying some of the features of our notion of scientific discovery, also participated in the economies of artworks and monuments. And as he was crafting such a new kind of product, he was also fashioning himself into a role—the philosopher and mathematician of the Medici grand duke—that had not quite existed before. Product, producer, and market were shaped simultaneously.

Galileo’s economies were new but grew from grafts. At each phase of his career, he made room for his claims and activities within economies that had been previously set up for something else. At Padua he developed a thriving instrument-making activity by attaching it to his conventional academic post; at the Medici court in Florence he crafted a new persona for himself by borrowing from the roles and profiles of court artists and literati; and during the controversy with the Inquisition he cast himself as a theologian by grafting his defense of astronomy and Copernicanism on the discourse of his censors. In time, the elements of his composite economies became increasingly less material (moving from brass instruments to textual devices), but their logic remained that of the graft.

On the verge of print

Galileo’s entrance into an economy of print was neither precocious nor glamorous. By the time he published his first book—a slim sixty-copy edition of an instruction manual of his “geometrical and military compass”—he was already forty-two. By the same age, Kepler had already published most of the major contributions to astronomy and optics (four key books and several shorter texts) for which he is famous today. What is more surprising is that, left to his own devices, Galileo might have further delayed the pleasure of seeing his name in print. In the preface to the 1606 Operations of the Geometrical and Military Compass he explained his decision to print as a response to hearing that someone was “getting ready to appropriate” his multipurpose calculating instrument. Up to that point he had been perfectly content to use manuscript copies of the compass’ instruction manual for his students, but now he wanted to enlist “the press as a witness” to his priority claims. He printed to control, not to communicate. Galileo’s preoccupation with credit and control over his work is evident in the text itself: while the Operations taught how to use the compass, it did not include any illustration or information about how to build it. Ten months later he entered a bitter dispute with a Paduan student, Baldassare Capra, whom he accused of plagiarizing both his book and his instrument.

Galileo’s life and career changed forever in 1610 with the publication of the Sidereus Nuncius—a description of his telescopic discoveries. But if the philosophical caliber of his claims had grown exponentially in the few years since the Operations, the circumstances of their printing were comparable. Galileo told a friend that the Nuncius was “written for the most part as the earlier sections were being printed,” fearing that “someone else might find the same things and precede me [to print].” Like the 1606 Operations, the 1610 Nuncius did not provide information to build the instrument that was so central to the claims made in the book. Concerns with credit and priority stayed with him for the rest of his life. As late as 1632 he remarked: “Many pride themselves of having many authorities to support their claims, but I would rather have been the first and only one to make those claims.”

If it is easy to make sense of Galileo’s view of print as a means to build or defend priority claims, it is more difficult to understand why he began to use it only, and reluctantly, in 1606. Given how prolific an author Galileo proved to be in the second half of his career, and the fact that he had been doing original work in mathematics since at least 1587, his absence from print until 1606 is all the more surprising. Much of that behavior is probably traceable to the practices and expectations of the professional economy to which he belonged at that time. Given the small size of their audience, mathematicians published relatively little and often communicated their discoveries and theorems to other specialists through letters or personal visits. Galileo’s contacts with Clavius, Guidobaldo, and Sarpi were of this kind. Furthermore, his 1594 patent for a water pump as well as his duties at the Venetian Arsenal point to Galileo’s participation in the community of inventors and engineers who tended to privilege trade secrets over publications. Finally, his position as mathematics professor at the university provided him with a steady, if modest, income without the need to publish. Newton’s minimal list of printed publications prior to the Principia indicates that Galileo was not the only mathematics professor to be unmoved by the charm of print. Kepler’s remarkable publication track reflects, in contrast, the unstable economy of patronage at the imperial court in Prague. Books allowed Kepler to maintain the kind of visibility needed to justify title and stipend of Imperial Mathematician—resources that did not depend on teaching duties—but also to supplement his irregularly paid salary with reliable bonuses from book dedications. For a university mathematician like Galileo, the production of pedagogical texts (like the Operations) would have been seen as a plus, but was not part of his job description.

Still, it is puzzling that Galileo did not publish on topics that were both cosmologically significant and of wide popular appeal like the lodestone (on which he experimented extensively at Padua) or on the nova of 1604. In the case of the nova, he did toy with the idea of publishing a book, but eventually chose to deliver only a few lectures at the university. Did he fear that the natural philosophers among his colleagues would object at seeing a mathematician trespass on their disciplinary turf in print? Or did he think that a few large lectures in front of a quasi-captive audience would reach more people (and enhance his local fame) more effectively than a printed text? But when more astronomical wonders like his own telescopic discoveries emerged six years later, he reversed course and first published a book on the topic, delivering lectures on them only later. In that case he seemed unwilling to publicize his findings before protecting his priority through the printed text.

Galileo’s shift from lectures to books to disseminate his observations may tell us a lot about his evolving perceptions of the nature, location, and size of the markets for his work. It is important, then, to get a sense of Galileo’s everyday activities in Padua during the first half of his career, before he became the star of early seventeenth-century astronomy and began to publish books at a fast clip.

From boardinghouse to court

Galileo’s Operations could be bought only at his house. Together with the small size of the printing, that arrangement confirms his concern with controlling the book’s readership. He knew most of the Operations’ readers personally, as they either frequented his house or rented rooms there. They were the students who studied fortification, mechanics, and other applied mathematics with Galileo outside of the normal university curriculum. Together with the Operations, several students bought another pricier homemade item, the “geometrical and military compass.” It was produced by Marcantonio Mazzoleni, a former employee of the Venetian Arsenal who had joined Galileo’s extended household with his wife and daughter in 1599. His main income came from selling Galileo compasses and other instruments, which Galileo then resold at a modest markup.

According to the figures in Galileo’s accounts from 1600-1, he sold about 1,000 lire’s worth of instruments in a year. While far from trivial, this sum was just a fraction of what he charged for room and board. In 1604, for instance, the “Hotel Galileo” took in about 7,500 lire from twenty paying guests. Private teaching was also very remunerative, earning him 3,312 lire in 1603 and 2,600 in 1604. Even when we set aside the earnings from instruments, Galileo more than tripled his annual university salary (1,600 lire until 1606) with private teaching and boardinghouse alone. Galileo, then, was not an instrument maker who provided instruction on how to use the products he made, but rather one who sold instruments to increase revenues from his other household activities. A sector brought him twice its price from lessons on how to use it, not to mention other classes students might take with him after having mastered the instrument. Tycho’s nephew—Otto Brahe—was quick to learn and paid only 106 lire for instrument and instruction, but slower students paid up to 180 lire for the classes alone. In the end, Galileo’s university salary represented a relatively small portion of his overall income, though it was his university position that made his other, more remunerative activities possible.

Galileo could not prevent the copying of his instruments and written instructions once they left Padua in the hands of his students, but he squeezed much credit out of them before their departure. It is difficult, however, to categorize what kind of credit this was. In science and science studies we find an opposition between credit as money and credit as reputation. The former is usually offered to instrument makers, engineers, or laboratory assistants while the latter is tied to authorship and professional authority, accrues around the scientist’s name, and resists quantification. But the notion of credit instantiated by Galileo’s accusations of plagiarism against Baldassare Capra does not readily fit either of those categories. Galileo pursued Capra—swiftly and relentlessly—for the piracy of an instrument and its instruction manual (the kind of grievance one would expect to see associated with claims of monetary damages). And yet he stated over and over that Capra’s actions had hurt his honor, not his purse. Galileo’s reaction was more than an attempt to cast himself above the monetary interests that allegedly drove artisans and instrument makers. Capra, in fact, did not simply appropriate Galileo’s book, but he also cast into doubt his original authorship of the instrument. By intimating that Galileo was greedy enough to print a book about an instrument he may have not invented without even including information on how to build it, and then to sell his copies of the instrument “at the highest cost,” Capra tried to cast him as a price-gouging artisan, not as a proper academician. These accusations endangered much more than Galileo’s revenues from the sales of a short instruction manual. By tarnishing his image as an academic, they also tarnished the integrity of the entire business he had grafted on it. We could say that “Galileo” was not just the name of an individual, but that it functioned a bit as a “brand name” attached to his whole web of operations. In this case, honor was money.

The audience for Capra’s attack was largely limited to Padua, the only place where his veiled references to Galileo could have been easily deciphered. It is unlikely that Galileo would have pursued Capra had he been a foreign author printing in, say, Amsterdam. Like the economy of credit and authority Galileo later developed around the Medici court, the credibility and profitability of his “operation” in Padua was a local affair that hinged on his university appointment and the networks branching off from that post.

In July 1610, only four months after the publication of the Nuncius, Galileo took up his new position of philosopher and mathematician of the grand duke of Tuscany. Different aspects of Galileo’s move from Padua back to Florence have been singled out as emblematic of that transition: from university to court; from a tolerant republic to a pope-dependent absolutist state; from mathematician to philosopher; and from a modest salary and heavy teaching load to a generous paycheck and much free time. He also went, in a matter of months, from making money selling compasses and other instruments to refusing to sell his much more coveted telescopes. More precisely, he went from selling compasses to anyone who wanted them to giving telescopes as gifts to a few people of his choosing (mostly princes and cardinals). This last shift suggests that the transition from Padua to Florence was not just between two jobs, two cities, or two titles, but between two different systems of exchange that attached credit and credibility to almost opposite practices. Galileo’s strikingly different publication patterns before and after 1610 indicate that printing was one of the key aspects of the economy he entered at about the time he moved to Florence.

There was not much need for print in his Paduan professional context. Most of what Galileo had to offer fell either into the category of artifacts (instruments) or into that of services (instruction and lodging). From Galileo’s teaching to Mazzoleni’s instruments up to the services provided by people who cooked and cleaned at the “Hotel Galileo,” what was provided was labor-intensive and inherently local. This work, however, had nonlocal effects. Most of Galileo’s clients and students returned home, spreading his instruments and name in the process. We could say that in this period Galileo did not print books but imprinted students. In the second half of his career, by contrast, he published books but did not have actual students—only fans and disciples.

In Padua, Galileo’s intellectual and economic interests (as well as his duties at the Venetian arsenal) brought him in close contact with the world of inventors, instrument makers, and military engineers. This is well known, but little attention has been given to the fact that in that period Galileo’s own mode of production and reward was artisanal. Everything he received credit for in Padua was labor-intensive, produced and delivered locally—and in person. Any additional credit or income meant additional labor. Nick Wilding has commented that there was a tangible ceiling to the size of Galileo’s Paduan economy: the more compasses he sold, the more he had to teach how to use them. He quickly ran out of time. Galileo’s desire to move to court may have reflected a dissatisfaction with the kind of economy he was in, not just with his university teaching duties, which, in fact, boiled down to a meager thirty hours of lecturing a year.

Seen in this light, printed texts like the Operations were not meant to expand Galileo’s credit the way a novel might earn royalties for a modern author, but rather to protect his finite, labor-intensive system of production and reward. According to Galileo the Operations was to function only as a memory aid to help recall the viva voce instructions the reader/student was to receive from the master himself. While printed books are associated with mobility and multiple contexts of reading, the Operations was a supplement to the classroom experience. As such, it lost much of its utility (for both the reader and Galileo) outside of that context.

When he arrived in Florence riding the wave of the Nuncius, he also entered the “age of mechanical reproduction” of his work, leaving the craft economy he had practiced in Padua. While he still had to provide highly customized, in-person services (the occasional philosophical entertainment at court, the rare instruction of the princes, or the replies to patrons’ questions), Galileo pursued a kind of credit he had not sought while at Padua. Now it was books that went to their unknown readers, not the students who went to his home to buy his book. The credit he now received from books did not require extra authorial labor, only a larger print run. A comparison between the sixty-copy print run of the 1606 Operations and the two-thousand-copy run of the 1613 Sunspots Letters speaks for itself.

With the expansion of Galileo’s market came a dramatic change in the function of his books. The Nuncius is the first book in which Galileo had to convince anybody of anything. The Operations did not have to convince the reader of the quality of the compass, or that it could perform the operations described. Most likely, by the time the student came to reading the book, he had already bought the instrument and signed up for classes. The Operations was an ordered compilation of ex professo statements about the use of the sector. It was handed to readers who, by assuming the role of the student, accepted the authority of the author-teacher even before the reading or the teaching began. And they accepted his authority not because he was the famous Galileo, but because he was the only professor of mathematics at the university. The Operations, then, treated the student-reader as a nonissue, exactly the way it treated the performance and value of Galileo’s instrument.

The students did not necessarily buy the compass because it was better or more original than other similar devices one could buy in Germany, France, or England. They bought it because they were there, Galileo was there, and he was their teacher. They trusted Galileo the way the residents of a certain neighborhood trust the local baker. They bought his goods because it would have been much less convenient (or in some cases materially impossible) to shop elsewhere.

In contrast, the credit his later books could generate for Galileo was unconnected to the sale of goods or services. The Nuncius could produce credit for Galileo only by convincing the reader of the new, controversial claims it presented. At once, Galileo stepped outside of the traditional boundaries of mathematics and outside the context of his pedagogical authority. In this new scenario credit became inextricably tied to credibility. The reader became an issue too. He was no longer a local customer, but a remote and typically unknown person who could contribute to Galileo’s symbolic capital only if he were made to accept, or at least not oppose, his book’s claims.

If Galileo’s books operated very differently in Padua and Florence, it does not mean that from 1610 he worked in a modern book market where his credit came from book sales. Like his Paduan students who may have paid for Galileo’s instruments and classes because he was the university professor of mathematics, his later readers granted Galileo’s books a certain amount of credibility because of his title of philosopher and mathematician of the grand duke of Tuscany. In both cases, Galileo’s market depended on the identity and location of his employer. “To depend,” however, meant different things in Padua and Florence.

The credit that Galileo earned within his clearly defined Paduan turf hinged on the perceived quality of his services, not on his priority claims over instruments or natural-philosophical discoveries. In Florence he could not count on a similarly well-delineated job description and sphere of credibility because his role at court was very much a work in progress. But if the authority bestowed by the unprecedented title of “philosopher and mathematician of the grand duke” was yet untested, it surely expanded his capacity to play on a larger, nonlocal scale. Galileo’s title traveled with the Medici name through Medici channels. Furthermore, the fact that he could now call himself a philosopher gave him key resources to gain credit for claims of a kind that was essentially external to his Paduan economy. Galileo’s credit in Padua depended primarily on the utility of his instruments, teaching, or patents. In Florence, on the other hand, we see that his credit stemmed mostly from being first at making new claims—claims whose immediate utility was much less of an issue. Novelty, priority, and utility seemed to trade roles in Galileo’s economy as he moved from Padua to Florence, from mathematics to natural philosophy.

Copyright notice: Excerpt from pages 1-13 of Galileo’s Instruments of Credit: Telescopes, Images, Secrecy by Mario Biagioli, published by the University of Chicago Press. ©2006 by the University of Chicago. All rights reserved. This text may be used and shared in accordance with the fair-use provisions of U.S. copyright law, and it may be archived and redistributed in electronic form, provided that this entire notice, including copyright information, is carried and provided that the University of Chicago Press is notified and no fee is charged for access. Archiving, redistribution, or republication of this text on other terms, in any medium, requires the consent of the University of Chicago Press. (Footnotes and other references included in the book may have been removed from this online version of the text.)

Mario Biagioli
Galileo’s Instruments of Credit: Telescopes, Images, Secrecy
©2006, 306 pages, 1 color plate, 15 halftones, 8 line drawings
Cloth $35.00 ISBN: 978-0-226-04561-0
Paper $20.00 ISBN: 978-0-226-04562-7

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