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

duchies, republics and papal states, united only by their common language, often at war with one another, and cut off from the rest of Europe by the Alps.

      The landscape changed. Spires of cedar and cypress trees soared out of the rolling terrain, while ochre stucco houses sank roots into it. Here Galileo introduced Livia to the earth tones and square, sensible beauty of Tuscany. His older daughter, Virginia, already awaited them in Florence. She had gone the previous autumn at the insistence of Galileo’s mother, who took Virginia home with her after an unhappy visit to Padua. Finding her son too absorbed in his new spyglass to extend the sort of hospitality she demanded, and her not-quite daughter-in-law not worthy of her attention, Madonna Giulia cut short her intended stay and returned to Tuscany.

      ‘The little girl is so happy here’, she crowed in a letter to Alessandro Piersanto, a servant in Galileo’s house, ‘that she will not hear that other place mentioned any more.’

      Neither Virginia nor Livia had any idea when they would ever see their brother Vincenzio again. For the time being at least, Galileo deemed it best for the boy, still a toddler, to remain in Padua with Marina.

      Soon after Galileo’s departure, Marina married Giovanni Bartoluzzi, a respectable citizen closer to her own social station. Galileo not only approved of their union but also helped Bartoluzzi find employment with a wealthy Paduan friend of his. Still, Galileo continued sending money to Marina for Vincenzio’s support, and Bartoluzzi, in turn, kept Galileo supplied with lens blanks for his telescopes, procured from the renowned glassworks on the island of Murano, within the waterways of Venice, until Florence proved a source of even better clear glass.

      Galileo rented a house in Florence ‘with a high terraced roof from which the whole sky is visible’, where he could make his astronomical observations and install his lens-grinding lathes. While waiting for the place to become available, he stayed several months with his mother and the two little girls in rooms he let from his sister Virginia and her husband, Benedetto Landucci. Galileo’s relatives provided an amicable enough atmosphere in their home, despite the recent legal fracas, but ‘the malignant winter air of the city’ made him miserable.

      ‘After the absence of so many years,’ Galileo lamented, ‘I have experienced the very thin air of Florence as a cruel enemy of my head and the rest of my body. Colds, discharges of blood, and constipation have during the last three months reduced me to such a state of weakness, depression and despondency that I have been practically confined to the house, or rather to my bed, but without the blessing of sleep or rest.’

      He devoted what time his health allowed to the problem of Saturn, much further away than Jupiter – at the apparent limit of his best telescope’s resolution – where he thought he could just discern two large, immobile moons. He described what he had seen in a Latin anagram, which, when correctly unscrambled, said, ‘I observed the highest planet to be triple-bodied.’ Thus staking his claim to the new discovery without making a fool of himself before establishing proper confirmation, he dispatched the anagram to several well-known astronomers. None of them correctly decoded it, however. The great Kepler in Prague, who by this point had held the telescope and deemed it ‘more precious than any sceptre’, misinterpreted the message to mean Galileo had discovered two moons at Mars.^*

      All through that same autumn of 1610, with Venus visible in the evening sky, Galileo studied the planet’s changing size and shape. He kept a telescope trained on Jupiter, too, in a protracted struggle to ascertain the precise orbital periods of the four new satellites further to validate their reality. Meanwhile, other astronomers complained of struggling just to catch sight of the Jovian satellites through inferior instruments, and therefore they questioned the bodies’ very existence. Despite Kepler’s endorsement, some sniped that the moons must be optical illusions, suspiciously introduced into the sky by Galileo’s lenses.

      Now that the moons had become matters of the Florentine state, this situation required immediate remedy to protect the honour of the grand duke. Galileo scrambled to build as many telescopes as he could for export to France, Spain, England, Poland, Austria, as well as for princes all around Italy. ‘In order to maintain and increase the renown of these discoveries,’ he reasoned, ‘it appears to me necessary…to have the truth seen and recognised, by means of the effect itself, by as many people as possible.’

      Famous philosophers, including some of Galileo’s former colleagues at Pisa, refused to look through any telescope at the purported new contents of Aristotle’s immutable cosmos. Galileo deflected their slurs with humour: learning of the death of one such opponent in December 1610, he wished aloud that the professor, having ignored the Medicean stars during his time on Earth, might now encounter them en route to Heaven.

      To cement the primacy of his claims, Galileo thought it politic to visit Rome and publicise his discoveries around the Eternal City. He had travelled there once before, in 1587, to discuss geometry with the pre-eminent Jesuit mathematician Christoph Clavius, who had written influential commentaries on astronomy, and who now would surely welcome news of Galileo’s recent work. Grand Duke Cosimo condoned the trip. He thought it might heighten his own stature in Rome, where his brother Carlo currently filled the traditional position of resident Medici cardinal.

      Unfortunately, Galileo’s sickly reaction to the air of Florence prevented him from setting out until 23 March 1611. He spent six days on the road in the grand duke’s litter, and at night he set up his telescope in every stop along the way – San Casciano, Siena, San Quirico, Acquapendente, Viterbo, Alonterosi – to continue tracking the revolutions of Jupiter’s moons.

      Upon Galileo’s arrival at the week’s end, the warmth of his Roman welcome surprised him. ‘I have been received and fêted by many illustrious cardinals, prelates and princes of this city,’ he reported, ‘who wanted to see the things I have observed and were much pleased, as I was too on my part in viewing the marvels of their statuary, paintings, frescoed rooms, palaces, gardens, etc.’

      Galileo garnered the powerful endorsement of the Collegio Romano, the central institution of the Jesuit educational net-work, where Father Clavius, now well into his seventies, was chief mathematician. He and his revered colleagues, regarded by the Church as the top astronomical authorities, had obtained telescopes of their own, and now as a group corroborated all of Galileo’s observations. Bound as these Jesuits were to Aristotelian belief in an unchanging cosmos, they did not deny the evidence of their senses. They even honoured Galileo with a rare invitation to visit.

      ‘On Friday evening of the past week in the Collegio Romano,’ a social bulletin reported in early April, ‘in the presence of cardinals and of the Marquis of Monticelli, its promoter, a Latin oration was recited, with other compositions in praise of Signor Galileo Galilei, mathematician to the grand duke, magnifying and exalting to the heavens his new observation of new planets that were unknown to the ancient philosophers.’

      This marquis of Monticelli who attended Galileo’s fête was an affable, idealistic young Roman named Federico Cesi. His handful of noble titles also pronounced him duke of Acquasparta and prince of San Polo and Sant’ Angelo. In addition to these honours he bore by birth, he had distinguished himself in 1603, at the age of eighteen, by founding the world’s first scientific society, the Lyncean Academy. Cesi pooled his wealth, foresight and curiosity to establish a forum free from university control or prejudice. He made the academy international from the outset – one of its four charter members being Dutch – and multidisciplinary by design: ‘The Lyncean Academy desires as its members philosophers who are eager for real knowledge and will give themselves to the study of nature, especially mathematics; at the same time it will not neglect the ornaments of elegant literature and philology, which, like graceful garments, adorn the whole body of science.’ The choice of the sharp-eyed lynx as totem emphasised the importance Cesi placed on faithful observation of Nature. At official ceremonies, Cesi sometimes wore a lynx pendant on a gold neck chain.

      Cesi entreated Galileo, who embodied the Lynceans’ organising principles, to join the academy during his stay in Rome. He held a banquet in Galileo’s honour on 14 April on the city’s highest hill, where one of the other dinner guests, Greek mathematician Giovanni Demisiani, proposed the name ‘telescope’