Cambridge Companions Online Cambridge University Press, 2006

WILLIAM A. WALLACE

1 Galileo's Pisan studies inscience and philosophy

The aura surrounding Galileo as founder of modern science disposesmany of those writing about him to start in medias res with anaccount of his discoveries with the telescope, or with his dialogueson the world systems and the two new sciences, or with the trialand the tragic events surrounding it. Frequently implicit in suchbeginnings is the attitude that Galileo had no forebears and standsapart from history, this despite the fact that he was forty-six years ofage when he wrote his Sidereus Nuncius and then in his late sixtiesand early seventies when he composed his two other masterpieces.

Attempts have recently been made by scholars to dispel this mythby giving closer scrutiny to the historical record - closer, that is, thanone gets from perusing the National Edition of Galileo's works.1 Thiswas a masterful collection, but begun as it was in the last decadeof the nineteenth century and completed in the first decade of thetwentieth, it perforce could not benefit from the historiographicaltechniques developed in our century. During the past twenty years,in particular, much research has been done on Galileo's manuscripts,and it sheds unexpected light on what has come to be known asGalileo's "early period" - that covering the first forty-five years ofhis life.2 This period has been singularly neglected by historians, andto their disadvantage, if the adage parvus error in initio magnus infine may be applied to the history of ideas.

PERSONS AND PLACES IN TUSCANY

Galileo's father, Vincenzio Galilei, was born in Florence in 1520and flourished there as a teacher of music and a lutanist of ability(Drake 1970). Having studied music theory for a while with

Cambridge Companions Online Cambridge University Press, 2006

Cambridge Companions Online Cambridge University Press, 2006

28 THE CAMBRIDGE COMPANION TO GALILEO

Gioseffo Zarlini in Venice, he married Guilia Ammannati of Pesciain 1563 and settled in the countryside near Pisa. There their firstchild, Galileo Galilei, was born on February 15, 1564. The familyreturned to Florence in 1572, but the young Galileo was left in Pisawith a relative of Guilia by marriage, Muzio Tedaldi, a businessmanand customs official.

Two years later, Galileo rejoined his family in Florence and wastutored there by Jacopo Borghini until he could be sent to the Camal-dolese Monastery at nearby Vallombrosa to begin his classical edu-cation. While at that monastery, Galileo was attracted to the lifeof the monks and actually joined the order as a novice. Vincenziowas displeased with the development, so he brought his son back toFlorence where he resumed his studies at a school run by the Carnal -dolese monks but no longer as a candidate for their order.

Vincenzio's plan for Galileo was to become a physician, followingin the footsteps of a fifteenth-century member of the family, alsonamed Galileo, who had achieved great distinction as a physicianand also in public affairs. Accordingly, he arranged for his son to liveagain with Tedaldi in Pisa and had him enrolled at the universitythere as a medical student in the fall of 15 81 (Drake 1978).

The next four years of his life Galileo spent at the University of Pisa,studying mainly philosophy, where his professors were FrancescoBuonamici and Girolamo Borro, and mathematics (including astron-omy) under a Camaldolese monk, Filippo Fantoni. He probably wentback to Florence for the summers, however, and this provides a keyto the way Galileo supplemented the instructions he received inmathematics from Father Fantoni.

It was the custom of the Tuscan court to move from Florence toPisa from Christmas to Easter of each year, and the court mathemati-cian at the time was Ostilio Ricci, a competent geometer who is saidto have studied under Niccolo Tartaglia (Settle 1971, Masotti 1975).During the 1582-1583 academic year, Galileo met Ricci while thelatter was at Pisa and sat in on lectures Ricci was giving on Euclidto the court pages.

The following summer, when Galileo was back home, supposedlyreading Galen, he invited Ricci to meet his father. Vincenzio was im-pressed with Ricci and the two became friends. Ricci told Vincenziothat his son was little interested in medicine, that he wanted to

Cambridge Companions Online Cambridge University Press, 2006

Cambridge Companions Online Cambridge University Press, 2006

Galileo's Pisan studies in science and philosophy 29

become a mathematician, and sought permission to instruct him inthat discipline. Despite Vincenzio's unhappiness with this request,Galileo was able to avail himself of Ricci's help and devote himselfmore and more to the study of Euclid and Archimedes, probably withthe aid of Italian translations prepared by Tartaglia.

By 1585, Galileo dropped out of the University of Pisa and be-gan to teach mathematics privately at Florence and at Siena, wherehe had a public appointment in 1585-1586, and then at Vallom-brosa in the summer of 1585. In 1587, Galileo traveled to Rome tovisit Christopher Clavius, the famous Jesuit mathematician at theCollegio Romano. And in 1588, he was invited to the FlorentineAcademy to give lectures on the location and dimensions of hell inDante's Inferno.

In 15 89, Fantoni relinquished the chair in mathematics at Pisa andGalileo was selected to replace him, partly because of the favorableimpression he had made on the Tuscan court with his lectures onDante and partly on the recommendation of Clavius and other math-ematicians who had become acquainted with his work. Galileo beganlecturing at Pisa in November 1589, along with Jacopo Mazzoni, aphilosopher who taught both Plato and Aristotle and was also anexpert on Dante, and the two quickly became friends (Purnell 1972,DePace 1993).

Mazzoni is of special interest because of his knowledge of theworks of another mathematician, Giovan Battista Benedetti, andbecause he is given special mention by Galileo in a letter from Pisaaddressed to his father in Florence and dated November 15, 1590.In it, Galileo requests that his seven-volume Galen and his Sfera besent to him at Pisa and informs his father that he is applying himself"to study and learning from Signor Mazzoni/7 who sends his regards(ENio:44-5).

Galileo then taught at the University of Pisa until 1592, whenfinancial burdens put on him as the eldest son at the death of hisfather in 1591 required him to obtain a better salary than the 60florins he was being paid. He sought and received an appointment atthe University of Padua at a salary of 180 florins, where he deliveredhis inaugural lecture on December 7, 1592.

He spent the next eighteen years in the Republic of Venice, whichhe later avowed were the happiest years of his life. Then he returned

Cambridge Companions Online Cambridge University Press, 2006

Cambridge Companions Online Cambridge University Press, 2006

30 THE CAMBRIDGE COMPANION TO GALILEO

to the Florentine court in 1610 as mathematician and philosopher toCosimo II de' Medici, the Grand Duke of Tuscany.

MANUSCRIPTS AND THE EXPANDED DATA BASE

We have touched on places and persons in Tuscany that played asignificant role in Galileo's intellectual development. The princi-pal locations are Pisa and Florence, with Vallombrosa and Siena ofsecondary importance, along with the outside trip to Rome, whichfortunately gave rise to materials that greatly enlarge the data baseon which we can work. Galileo left a number of manuscripts datingfrom about 1580 to 1592, most in his own hand and in Latin, muchof it on watermarked paper. Antonio Favaro transcribed some ofthe manuscripts for the National Edition and made a few notationsregarding Galileo's peculiar spelling of Latin terms.

He also was able to identify two sources Galileo used for note tak-ing, both translations of Plutarch's Opuscoli Morali, one publishedat Venice in 1559 and the other at Lucca in 1560 (EN9:277-8). Apartfrom this, Favaro could only conjecture about Galileo's sources andthe periods during which he composed the various manuscripts thatmake up his Tuscan heritage, most of which are still conserved inFlorence's Biblioteca Nazionale Centrale.

Serious work on these materials began around 1970, when StillmanDrake worked out a technique for dating Galileo's manuscriptsthrough a study of the watermarks on the paper on which they werewritten and when other scholars, myself included, began to uncoverthe source materials on which the natural philosophy contained inone of the manuscripts was based.3 Over the past twenty-five years,this research has expanded to include full studies of watermarks(Camerota 1993), detailed paleographical studies of Galileo's hand-writing and word choice (Hooper 1993), and analyses of the ink heused when writing the manuscripts (Hooper 1994).4

Research on the sources of Galileo's philosophy proved particu-larly fruitful, since it turned out that a large part of that philosophywas appropriated from notes of lectures given in Rome by Jesuit pro-fessors of the Collegio Romano - the prestigious university estab-lished in that city by the founder of the Jesuits, Ignatius Loyola.Although Galileo did not attend those lectures, he somehow ob-tained copies of them and then appropriated selected materials for

Cambridge Companions Online Cambridge University Press, 2006