Galileo’s Daughter: A Drama of Science, Faith and Love

Galileo’s Daughter
A drama of science, faith and love
Dava Sobel

To the fathers,

Galileo Galilei

&

Samuel Hillel Sobel, MD,

in loving memory

Table of Contents

Cover Page

Title Page

PART ONE To Florence

[I] She who was so precious to you

[II] This grand book the universe

[III] Bright stars speak of your virtues

[IV] To have the truth seen and recognised

[V] In the very face of the Sun

[VI] Observant executrix of God’s commands

[VII] The malice of my persecutors

[VIII] Conjecture here among shadows

PART TWO On Bellosguardo

[IX] How our father is favoured

[X] To busy my self in your service

[XI] What we require above all else

[XII] Because of our zeal

[XIII] Through my memory of their eloquence

[XIV] A small and trifling body

[XV] On the right path by the grace of God

[XVI] The tempest of our many torments

PART THREE In Rome

[XVII] While seeking to immortalise your fame

[XVIII] Since the Lord chastises us with these whips

[XIX] The hope of having you always near

[XX] That I should be begged to publish such a work

PART FOUR Care of the Tuscan Embassy, Villa Medici, Rome

[XXI] How anxiously I live, awaiting word from you

[XXII] In the comfort of the Holy Office of the Inquisition

[XXIII] Vainglorious ambition, pure ignorance and inadvertence

[XXIV] Faith rested in the miraculous Madonna of Imprueta

[XXV] Judgment passed on your book and your person

PART FIVE At Siena

[XXVI] Not knowing how to refuse him the keys

[XXVII] Terrible destruction on the feast of San Lorenzo

[XXVIII] Recitation of the penitential psalms

[XXIX] The book of life, or, A prophet accepted in his own land

PART SIX From Arcetri

[XXX] My soul and its longing

[XXXI] Until I have this from your lips

[XXXII] As I struggle to understand

[XXXIII] The memory of the sweetnesses

IN GALILEO’S TIME

FLORENTINE WEIGHTS, MEASURES, CURRENCY

BIBLIOGRAPHY

NOTES

APPRECIATION

INDEX

About the Author

Praise

Copyright

About the Publisher

PART ONE To Florence

[I] She who was so precious to you

MOST ILLUSTRIOUS LORD FATHER

WE ARE TERRIBLY SADDENED by the death of your cherished sister, our dear aunt; but our sorrow at losing her is as nothing compared to our concern for your sake, because your suffering will be all the greater, Sire, as truly you have no one else left in your world, now that she, who could not have been more precious to you, has departed, and therefore we can only imagine how you sustain the severity of such a sudden and completely unexpected blow. And while I tell you that we share deeply in your grief, you would do well to draw even greater comfort from contemplating the general state of human misery, since we are all of us here on Earth like strangers and wayfarers, who soon will be bound for our true homeland in Heaven, where there is perfect happiness, and where we must hope that your sister’s blessed soul has already gone. Thus, for the love of God, we pray you, Sire, to be consoled and to put yourself in His hands, for, as you know so well, that is what He wants of you; to do otherwise would be to injure yourself and hurt us, too, because we lament grievously when we hear that you are burdened and troubled, as we have no other source of goodness in this world but you.

I will say no more, except that with all our hearts we fervently pray the Lord to comfort you and be with you always, and we greet you dearly with our ardent love.

FROM SAN MATTEO, THE 10TH DAY OF MAY 1623.

Most affectionate daughter,

S. Maria Celeste

The day after his sister Virginia’s funeral, the already world-renowned scientist Galileo Galilei received this, the first of 124 surviving letters from the once-voluminous correspondence he carried on with his elder daughter. She alone of Galileo’s three children mirrored his own brilliance, industry and sensibility, and by virtue of these qualities became his confidante.

Galileo’s daughter, born of his long illicit liaison with the beautiful Marina Gamba of Venice, entered the world in the summer heat of a new century, on 13 August 1600 – the same year the Dominican friar Giordano Bruno was burned at the stake in Rome for insisting, among his many heresies and blasphemies, that the Earth travelled around the Sun, instead of remaining motionless at the centre of the universe. In a world that did not yet know its place, Galileo would engage this same cosmic conflict with the Church, treading a dangerous path between the Heaven he revered as a good Catholic and the heavens he revealed through his telescope.

Galileo christened his daughter Virginia, in honour of his ‘cherished sister’. But because he never married Virginia’s mother, he deemed the girl herself unmarriageable. Soon after her thirteenth birthday, he placed her at the Convent of San Matteo in Arcetri, where she lived out her life in poverty and seclusion.

Virginia adopted the name Maria Celeste when she became a nun, in a gesture that acknowledged her father’s fascination with the stars. Even after she professed a life of prayer and penance, she remained devoted to Galileo as though to a patron saint. The doting concern evident in her condolence letter was only to intensify over the ensuing decade as her father grew old, fell more frequently ill, pursued his singular research nevertheless, and published a book that brought him to trial by the Holy Office of the Inquisition.

The ‘we’ of Suor Maria Celeste’s letter speaks for herself and her sister, Livia – Galileo’s strange, silent second daughter, who also took the veil and vows at San Matteo to become Suor Arcangela. Meanwhile their brother, Vincenzio, the youngest child of Galileo and Marina’s union, had been legitimised in a fiat by the grand duke of Tuscany and gone off to study law at the University of Pisa.

Thus Suor Maria Celeste consoled Galileo for being left alone in his world, with daughters cloistered in the separate world of nuns, his son not yet a man, his former mistress dead, his family of origin all deceased or dispersed.

Galileo, now fifty-nine, also stood boldly alone in his world-view, as Suor Maria Celeste knew from reading the books he wrote and the letters he shared with her from colleagues and critics all over Italy, as well as from across the continent beyond the Alps. Although her father had started his career as a professor of mathematics, teaching first at Pisa and then at Padua, every philosopher in Europe tied Galileo’s name to the most startling series of astronomical discoveries ever claimed by a single individual.

In 1609, when Suor Maria Celeste was still a child in Padua, Galileo had set a telescope in the garden behind his house and turned it skywards. Never-before-seen stars leaped out of the darkness to enhance familiar constellations; the nebulous Milky Way resolved into a swath of densely packed stars; mountains and valleys pockmarked the storied perfection of the Moon; and a retinue of four attendant bodies travelled regularly around Jupiter like a planetary system in miniature.

‘I render infinite thanks to God’, Galileo intoned after those nights of wonder, ‘for being so kind as to make me alone the first observer of marvels kept hidden in obscurity for all previous centuries.’

The new-found worlds transformed Galileo’s life. He won appointment as chief mathematician and philosopher to the grand duke in 1610, and moved to Florence to assume his position at the court of Cosimo de’ Medici. He took along with him his two daughters, then ten and nine years old, but he left Vincenzio, who was only four when greatness descended on the family, to live a while longer in Padua with Marina.

Galileo found himself lionised as another Columbus for his conquests. Even as he attained the height of his glory, however, he attracted enmity and suspicion. For instead of opening a distant land dominated by heathens, Galileo trespassed on holy ground. Hardly had his first spate of findings stunned the populace of Europe before a new wave followed: he saw dark spots creeping continuously across the face of the Sun, and ‘the mother of loves’, as he called the planet Venus, cycling through phases from full to crescent, just as the Moon did.

All his observations lent credence to the unpopular Sun-centred universe of Nicolaus Copernicus, which had been introduced over half a century previously but foundered on lack of evidence. Galileo’s efforts provided the beginning of a proof. And his flamboyant style of promulgating his ideas – sometimes in bawdy humorous writings, sometimes loudly at dinner parties and staged debates – transported the new astronomy from the Latin Quarters of the universities into the public arena. In 1616, a pope and a cardinal inquisitor reprimanded Galileo, warning him to curtail his forays into the supernal realms. The motions of the heavenly bodies, they said, having been touched upon in the Psalms, the Book of Joshua, and elsewhere in the Bible, were matters best left to the Holy Fathers of the Church.

Galileo obeyed their orders, silencing himself on the subject. For seven cautious years he turned his efforts to less perilous pursuits, such as harnessing his Jovian satellites in the service of navigation, to help sailors discover their longitude at sea. He studied poetry and wrote literary criticism. Modifying his telescope, he developed a compound microscope. ‘I have observed many tiny animals with great admiration,’ he reported, ‘among which the flea is quite horrible, the gnat and the moth very beautiful; and with great satisfaction I have seen how flies and other little animals can walk attached to mirrors, upside down.’

Shortly after his sister’s death in May of 1623, however, Galileo found reason to return to the Sun-centred universe like a moth to a flame. That summer a new pope ascended the throne of Saint Peter in Rome. The Supreme Pontiff Urban VIII brought to the Holy See an intellectualism and an interest in scientific investigation not shared by his immediate predecessors. Galileo knew the man personally – he had demonstrated his telescope to him and the two had taken the same side one night in a debate about floating bodies after a banquet at the Florentine court. Urban, for his part, had admired Galileo so long and well that he had even written a poem for him, mentioning the sights revealed by ‘Galileo’s glass’.

The presence of the poet pope encouraged Galileo to proceed with a long-planned popular dissertation on the two rival theories of cosmology: the Sun-centred and the Earth-centred, or, in his words, the ‘two chief systems of the world’.

It might have been difficult for Suor Maria Celeste to condone this course – to reconcile her role as a bride of Christ with her father’s position as potentially the greatest enemy of the Catholic Church since Martin Luther. But instead she approved of his endeavours because she knew the depth of his faith. She accepted Galileo’s conviction that God had dictated the Holy Scriptures to guide men’s spirits but proffered the unravelling of the universe as a challenge to their intelligence. Understanding her father’s prodigious capacity in this pursuit, she prayed for his health, for his longevity, for the fulfilment of his ‘every just desire’. As the convent’s apothecary, she concocted elixirs and pills to strengthen him for his studies and protect him from epidemic diseases. Her letters, animated by her belief in Galileo’s innocence of any heretical depravity, carried him through the ordeal of his ultimate confrontation with Urban and the Inquisition in 1633.

No detectable strife ever disturbed the affectionate relationship between Galileo and his daughter. Theirs is not a tale of abuse or rejection or intentional stifling of abilities. Rather, it is a love story, a tragedy and a mystery.

Most of Suor Maria Celeste’s letters travelled in the pocket of a messenger, or in a basket laden with laundry, sweetmeats or herbal medicines, across the short distance from the Convent of San Matteo, on a hillside just south of Florence, to Galileo in the city or at his suburban home. Following the angry papal summons to Rome in 1632, however, the letters rode on horseback some two hundred miles and were frequently delayed by quarantines imposed as the Black Plague spread death and dread across Italy. Gaps of months’ duration disrupt the continuity of the reportage in places, but every page is redolent of daily life, down to the pain of toothache and the smell of vinegar.

Galileo held on to his daughter’s missives indiscriminately, collecting her requests for fruits or sewing supplies alongside her outbursts on ecclesiastical politics. Similarly, Suor Maria Celeste saved all of Galileo’s letters, as rereading them, she often reminded him, gave her great pleasure. By the time she received the last rites, the letters she had gathered over her lifetime in the convent constituted the bulk of her earthly possessions. But then the mother abbess, who would have discovered Galileo’s letters while emptying Suor Maria Celeste’s cell, apparently buried or burned them out of fear. After the celebrated trial at Rome, a convent dared not harbour the writings of a ‘vehemently suspected’ heretic. In this fashion, the correspondence between father and daughter was long ago reduced to a monologue.

Standing in now for all the thoughts he once expressed to her are only those he chanced to offer others about her. ‘A woman of exquisite mind,’ Galileo described her to a colleague in another country, ‘singular goodness, and most tenderly attached to me.’

On first learning of Suor Maria Celeste’s letters, people generally assume that Galileo’s replies must lie concealed somewhere in the recesses of the Vatican Library, and that if only an enterprising outsider could gain access, the missing half of the dialogue would be found. But, alas, the archives have been combed, several times, by religious authorities and authorised researchers all desperate to hear the paternal tone of Galileo’s voice. These seekers have come to accept the account of the mother abbess’s destruction of the documents as the most reasonable explanation for their disappearance. The historical importance of any paper signed by Galileo, not to mention the prices such articles have commanded for the past two centuries, leaves few conceivable places where whole packets of his letters could hide.

Although numerous commentaries, plays, poems, early lectures and manuscripts of Galileo’s have also disappeared (known only by specific mentions in more than two thousand preserved letters from his contemporary correspondents), his enormous legacy includes his five most important books, two of his original handmade telescopes, various portraits and busts he sat for during his lifetime, even parts of his body preserved after death. (The middle finger of his right hand can be seen, encased in a gilded glass egg atop an inscribed marble pedestal at the Museum of the History of Science in Florence.)

Of Suor Maria Celeste, however, only her letters remain. Bound into a single volume with cardboard and leather covers, the frayed, deckle-edged pages now reside among the rare manuscripts at Florence’s National Central Library. The handwriting throughout is still legible, though the once-black ink has turned brown. Some letters bear annotations in Galileo’s own hand, for he occasionally jotted notes in the margins about the things she said and at other times made seemingly unrelated calculations or geometric diagrams in the blank spaces around his address on the verso. Several of the sheets are marred by tiny holes, torn, darkened by acid or mildew, smeared with spilled oil. Of those that are water-blurred, some obviously ventured through the rain, while others look more likely tear-stained, either during the writing or the reading of them. After nearly four hundred years, the red sealing wax still sticks to the folded corners of the paper.

These letters, which have never been published in translation, recast Galileo’s story. They recolour the personality and conflict of a mythic figure, whose seventeenth-century clash with Catholic doctrine continues to define the schism between science and religion. For although science has soared beyond his quaint instruments, it is still caught in his struggle, still burdened by an impression of Galileo as a renegade who scoffed at the Bible and drew fire from a Church blind to reason.

This pervasive, divisive power of the name Galileo is what Pope John Paul II tried to tame in 1992 by reinvoking his torment so long after the fact. ‘A tragic mutual incomprehension’, His Holiness observed of the 350-year Galileo affair, ‘has been interpreted as the reflection of a fundamental opposition between science and faith.’

Yet the Galileo of Suor Maria Celeste’s letters recognised no such division during his lifetime. He remained a good Catholic who believed in the power of prayer and endeavoured always to conform his duty as a scientist with the destiny of his soul. ‘Whatever the course of our lives,’ Galileo wrote, ‘we should receive them as the highest gift from the hand of God, in which equally reposed the power to do nothing whatever for us. Indeed, we should accept misfortune not only in thanks, but in infinite gratitude to Providence, which by such means detaches us from an excessive love for Earthly things and elevates our minds to the celestial and divine.’

[II] This grand book the universe

THE RECENTLY DECEASED RELATIVE Suor Maria Celeste mourned in her first extant letter was Virginia Galilei Landucci, the aunt she’d been named after. At the Convent of San Matteo, she shared her grief with her natural sister, Suor Arcangela (originally the namesake of Galileo’s other sister, Livia), and also with her cousin Suor Chiara – the departed Virginia’s own daughter Virginia.

A repetition of recollected identities echoed through the Galilei family like the sound of chanting, with its most melodic expression in the poetic rhythm of the great scientist’s full name. By accepted practice among established Tuscan families in the mid-sixteenth

century, when Galileo was born, the eldest son might well receive a Christian name derived from his parents’ surname. Accordingly, Vincenzio Galilei and his new wife, Giulia Ammannati Galilei, attracted no special attention when they gave the name Galileo to their first child, born at Pisa on the 15th day of February in the year of Our Lord 1564. (The year was actually recorded as 1563 in the chronicles of that period, however, when New Year’s Day fell on 25 March – the feast of the Annunciation.)

The family name Galilei, ironically, had itself been created from the first name of one of its foremost favourite sons. This was the renowned doctor Galileo Buonaiuti, who taught and practised medicine during the early 1400s in Florence, where he also served the government loyally. His descendants redubbed themselves the Galilei family in his honour and wrote ‘Galileo Galilei’ on his tombstone, but retained the coat of arms that had belonged to the ancestral Buonaiutis since the thirteenth century – a red step-ladder on a gold shield, forming a pictograph of the word buonaiuti, which literally means ‘good help’. The meaning of the name Galileo, or Galilei, harks back to the land of Galilee, although, as Galileo explained on this score, he was not at all a Jew.

Galileo Galilei took a few tentative steps along his famous forebear’s path, studying medicine for two years at the University of Pisa, before he gave himself over to the pursuit of mathematics and physics, his true passion. ‘Philosophy is written in this grand book the universe, which stands continually open to our gaze,’ Galileo believed. ‘But the book cannot be understood unless one first learns to comprehend the language and to read the alphabet in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures, without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.’

Galileo’s father had opposed the idea of his becoming a mathematician and tried, arguing from long personal experience with mathematics and patrician poverty, to dissuade his son from choosing such a poorly paid career.

Vincenzio made a minimal living giving music lessons in the rented Pisan house where Galileo was born and partly raised. He also dabbled in the business dealings of his wife’s family, the Ammannati cloth merchants, to supplement his small teaching income, but he was at heart a composer and musical theorist in the days when musical theory was considered a special branch of mathematics. Vincenzio taught Galileo to sing and to play the organ and other instruments, including the recently remodelled lute, which became their favourite. In the course of this instruction he introduced the boy to the Pythagorean rule of musical ratios, which required strict obedience in tuning and composition to numerical properties of notes in a scale. But Vincenzio subjected these prevailing rules to his own studies on the physics of sound. Music, after all, arose from vibrations in the air, not abstract concepts regarding whole numbers. Using this philosophy, Vincenzio established an ideal tuning formula for the lute by fractionally shortening the intervals between successive frets.

After Vincenzio moved to Florence with his wife in 1572, temporarily leaving Galileo behind in the care of relatives, he joined other virtuoso performers, scholars and poets bent on reviving classic Greek tragedy with music.^* Vincenzio later wrote a book defending the new trend in tuning that favoured the sweetness of the instrument’s sound over the ancient adherence to strict numerical relationships between notes. This book openly challenged Vincenzio’s own former music teacher, who prevented its publication in Venice in 1578. Vincenzio persevered, however, until he saw the work printed in Florence three years later. None of these lessons in determination or challenge to authority was lost on the young Galileo.

‘It appears to me’, Vincenzio stated in his Dialogue of Ancient and Modern Music, ‘that they who in proof of any assertion rely simply on the weight of authority, without adducing any argument in support of it, act very absurdly. I, on the contrary, wish to be allowed freely to question and freely to answer you without any sort of adulation, as well becomes those who are in search of truth.’

When Galileo was ten, he journeyed across Tuscany to join his parents and his infant sister, Virginia, in Florence. He attended grammar school near his new home until his thirteenth year, then moved into the Benedictine monastery at Vallombrosa to take instruction in Greek, Latin and logic. Once there, he joined the order as a novice, hoping to become a monk himself, but his father wouldn’t let him. Vincenzio withdrew Galileo and took him home, blaming an inflammation in the youth’s eyes that required medical attention. Money more likely decided the issue, for Vincenzio could ill afford the down payment and regular upkeep required to support his son in a religious vocation that generated no income. A girl was different. Vincenzio would have to pay dowries for his daughters, either to the Church or to a husband, and he could expect no return on either investment. Thus Vincenzio needed Galileo to grow up gainfully employed, preferably as a doctor, so he could help support his younger sisters, now four in number, and two brothers.

Vincenzio planned to send Galileo back to Pisa, to the College of the Sapienza, as one of forty Tuscan boys awarded free tuition and board, but couldn’t obtain the necessary scholarship. A good friend of Vincenzio’s in Pisa offered to take Galileo into his own home, to reduce the cost of the boy’s education. Vincenzio, however, hearing that this friend was romancing one of Galileo’s Ammannati cousins, held off for three years until the love affair ended in marriage and made the house a respectable residence for his son.

In September of 1581, Galileo matriculated at the University of Pisa, where medicine and mathematics both fitted into the Faculty of Arts. Although he applied himself to the medical curriculum to please his father, he much preferred mathematics from the moment he encountered the geometry of Euclid in 1583. After four years of formal study, Galileo left Pisa in 1585, at the age of twenty-one, without completing the course requirements for a degree.

Galileo returned to his father’s house in Florence. There he began behaving like a professional mathematician – writing proofs and papers in geometry, going out to give occasional public lectures, including two to the Florentine Academy on the conic configuration of Dante’s Inferno, and tutoring private students. Between 1588 and 1589, when Vincenzio filled a room with weighted strings of varying lengths, diameters and tensions to test certain harmonic ideas, Galileo joined him as his assistant. It seems safe to say that Galileo, who gets credit for being the father of experimental physics, may have learned the rudiments and value of experimentation from his own father’s efforts.

Having impressed several established mathematicians with his talent, Galileo procured a teaching post at the University of Pisa in 1589 and returned once more to the city of his birth at the mouth of the River Arno. The flooding of the river in fact delayed Galileo’s arrival on campus, so that he missed his first six lectures and found himself fined for these absences. By the end of the year, the university authorities were docking his pay for a different sort of infraction: his refusal to wear the regulation academic regalia at all times.

Galileo deemed official doctoral dress a pretentious nuisance, and he derided the toga in a three-hundred-line verse spoof that enjoyed wide readership in that college town. Any kind of clothing got in the way of men’s and women’s frank appraisals of each other’s attributes, he argued in ribald rhyme, while professional uniforms hid the true merits of character under a cloak of social standing. Worse, the dignity of the professor’s gown barred him from the brothel, denying him the evil pleasures of whoring while resigning him to the equally sinful solace of his own hands. The gown even impeded walking, to say nothing of working.

A long black robe would surely have hindered Galileo’s progress up the Leaning Tower’s eight-storey spiral staircase, laden, as legend has it, with cannonballs to demonstrate a scientific principle. In that infamous episode, the weight of iron on the twenty-five-year-old professor’s shoulders was as nothing compared to the burden of Aristotelian thought on his students’ perceptions of reality. Not only Galileo’s classes at Pisa, but university communities all over Europe, honoured the dictum of Aristotelian physics that objects of different weights fall at different speeds. A cannonball of ten pounds, for example, would be expected to fall ten times faster than a musket ball of only one pound, so that if both were released together from some summit, the cannonball would land before the musket ball had got more than one-tenth of the way to the ground. This made perfect sense to most philosophical minds, though the thought struck Galileo as preposterous. ‘Try, if you can,’ Galileo exhorted one of his many opponents, ‘to picture in your mind the large ball striking the ground while the small one is less than a yard from the top of the tower.’

‘Imagine them joining together while falling,’ he appealed to another debater. ‘Why should they double their speed as Aristotle claimed?’ If the incongruity of these mid-air scenarios didn’t deflate Aristotle’s ideas, it was a simple enough matter to test his assertions with real props in a public setting.

Galileo never recorded the date or details of the actual demonstration himself but recounted the story in his old age to a young disciple, who included it in a posthumous biographical sketch. However dramatically Galileo may have executed the event, he did not succeed in swaying popular opinion down at the base of the Leaning Tower. The larger ball, being less susceptible to the effects of what Galileo recognised as air resistance, fell faster, to the great relief of the Pisan philosophy department. The fact that it fell only fractionally faster gave Galileo scant advantage.

‘Aristotle says that a hundred-pound ball falling from a height of a hundred braccia [arm lengths] hits the ground before a one-pound ball has fallen one braccio. I say they arrive at the same time,’ Galileo resummarised the dispute in its aftermath. ‘You find, on making the test, that the larger ball beats the smaller one by two inches. Now, behind those two inches you want to hide Aristotle’s ninety-nine braccia and, speaking only of my tiny error, remain silent about his enormous mistake.’