"... alas, my lord, your dear friend and servant Galileo has for the past month become irreparably blind. Now imagine, Your Lordship, how afflicted I am as I think about that sky, that world and that universe which I with my marvellous observations and clear demonstrations had opened up hundreds and thousands of times more than had been commonly seen by the sages of all bygone centuries; now for me it is diminished and limited so that it is not any greater than the space I occupy."124
Two New Sciences was a publishing success. The book aroused particular interest in Germany and France, and a French translation was ready within a year. But fifty copies also found their way to Rome, without anyone trying to prevent it - in fact, Cardinal Francesco Barberini bought the book himself. As it had been printed outside the Inquisition's jurisdiction and, as it patently did not contain a trace of Copernicanism, the book was left alone and quickly sold out.
A copy eventually found its way to Arcetri and the Villa Il Gioiello. But by the time Galileo had the book in his hands, he was completely blind.
Galileo worked on with intensity, both while his sight slowly dimmed and after he had become enveloped in total darkness. The prohibitions that circumscribed his freedom of action were never officially lifted, but gradually things became somewhat easier. Two young pupils moved in and did his letter writing and read aloud to him: first, the barely sixteen-year old Vincenzio Viviani, then in Galileo's final months the older and later more renowned Evangelista Torricelli, who took up the torch of the master's ideas concerning atmospheric pressure, and constructed the first barometer.
Before he lost his sight, Galileo managed to make one last important astronomical observation using his beloved telescope. He had studied the Moon for more than 25 years. No other person knew every detail of its surface as he did. Now he realised that occasionally it was possible to see small areas that usually did not form part of the visible area. He was able to determine that this heavenly body displayed a minute "rocking" movement when seen from the Earth. He called the phenomenon the libration of the Moon.
The letter he wrote to Father Micanzio in Venice about this libration contains a couple of noteworthy sentences. Galileo wonders if the phenomenon
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can have an effect on the tides! And as if that were not sufficient, he rounds off with:
"... [the tides] which by the common consent of all, the moon is the referee and superintendent."125
In this little clause lies the undermining of the entire fourth day of the Dialogue. In the quietness of his isolation, Galileo had begun to doubt his great idea, his epoch-making and definitive proof of the Copernican system. He had - quite contrary to his normal instinct - begun to move towards "the common consent of all" [comune consenso di tutti].
It is hard to conceive that this happened for religious reasons, or out of respect for the Inquisition's judgement. Maybe Kepler's argument had finally made an impression on him, or perhaps he had simply gone through his own reasonings once more and seen the weakness of them. If so, this was one of his greatest intellectual achievements: it is one thing to see through the failing arguments of others, quite another to examine a line of reasoning that has formed a central plank in one's own view of the world, carefully and critically.
Another old project close to his heart, still took up a lot of Galileo's time. This was fixing longitude by exploiting the satellites of Jupiter -the characteristic combination of cutting-edge science and sober, practical application.
Galileo's great admirer in Amsterdam, the mathematician Hortensius, was given the task of working out the possibility of securing the rights of this for the Netherlands. He was undaunted by the practical difficulties the observations posed. Hortensius contacted Galileo, and had planned a journey to Italy. But suddenly this talented man died at the age of just 34, in 1639. This put paid to the maritime use of the Medicean stars for good.
The blind old man at Il Gioiello was one of the most famous men in Europe, and despite the embargo on visits, colleagues and admirers came in secret to pay their respects. One of them was John Milton. That great and thoroughly learned English poet was deeply interested in astronomy. In his principal work Paradise Lost the struggle between God, Satan and the angels is set in a carefully constructed universe, although largely built on Ptolemaic principles, mainly out of poetic considerations. Milton (who would also live to be blind and isolated in his old age) used the experiences of his meeting with Galileo in a domestic political context. He was one of Cromwell's supporters and emphasised the relative freedom of thought that existed in England, as opposed to the Catholic intolerance that had affected Galileo so deeply.
However, Galileo also received discreet assistance and support from the Church as well.126
The so-called Piarist movement was a peaceful order of kindly, learned brothers. The order was well represented in Tuscany and enjoyed the especial goodwill of Grand Duke Ferdinando. The Piarists ran what was called scuole pie - "pious schools" but, in contrast to the powerful and intellectually aristocratic Jesuits, they worked quietly at the grass roots, giving elementary education to poor children in reading, writing and arithmetic.
In certain places - including Florence - the Piarists had also begun to give higher education, in a very modest and low key manner so as not to upset the Jesuits. The Grand Duke was so pleased with this that he allowed one prominent Piarist to teach two of his younger brothers. He also looked favourably on the fact that, in practice, Father Clemente Settimi took on the role of Galileo's secretary. It was to Settimi that the indefatigable Galileo at an age of 76 dictated a letter containing his thoughts on the cycloid, the curve described by a fixed point on a circle that rolls along a line.
Father Clemente also functioned as Galileo's nurse. It was against the rules of the order to spend the night outside the cloister, but the monk got special permission from Rome, so that he could stay with Galileo when necessary.
It was not merely pious humanity that drove the Piarists in Florence to help Galileo. Settimi and other brothers with a mathematical education were in reality convinced Copernicans. But the Inquisition had merely relaxed its grip a little in regard to Galileo; it certainly did not slumber. And so Clemente Settimi's efforts for the old man came to an abrupt end when a member of the order reported his mathematical colleagues to the Holy Office:
"All the above maintain that there is no truer or surer science than that which Galileo teaches with the help of mathematics; they term it new philosophy and the true way to philosophise, and they have many times said (...) that it is the true way to learn to get to know God (.. .)"127
Neither the Pope nor the Holy Office could tolerate such ideas spreading within the Church, no matter how devout the Piarist Order was in its day-to-day running. The order was dissolved in 1646.
The person who was closest to Galileo in his last years, apart from his young pupil Viviani, was his son. The clashes that had soured their
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relationship in Vincenzio's younger days were gone. His son had become a responsible family man, and it was to him that Galileo confided his very last project.
It was quite unnecessary to use the satellites of Jupiter to establish longitude. The only advantage they had was that their eclipses were many and predictable - they were simply to be used to fix the time accurately. The whole thing could be done much more simply if one could just construct a temporal timepiece that was absolutely dependable.
Galileo may have had the idea earlier but in 1641, at the age of 77, he tried to breathe life into it. Sixty years earlier he had discovered that small pendulum movements were a sort of measurement of time, but he had used this for nothing except his curious pulsilogium. Now he knew a lot more about the characteristics of the pendulum, and realised that theoretically it could be used as the heart of a machine for measuring time - a perfect clock. But he could not sketch out the principle himself, far less construct a working model.
So he summoned his son and explained the idea, an idea which might secure the family's future prosperity if it could be manufactured. But Vin-cenzio was no enterprising innovator like his father. He let the project lie, and so it was the Dutchman, Christiaan Huygens, who eventually made the first working pendulum clock in 1656, in perfect keeping with the shift of science and technology to northern Europe.
In the autumn of 1641 the 33-year-old Evangelista Torricelli came to Il Gioiello. It was he who was to take down Galileo's last thoughts.
The Grand Duke's old mathematician turned back to Euclid at the last, a companion throughout his long life and the very foundation of his attempts to "read" nature - "this grand book (...) which stands continuously open to our gaze".
In the fifth book of Euclid's Elements the general rules of proportionality are defined, both those of arithmetical quantities (numbers) and geometrical ones (areas, bodies). Sick and bed-ridden, unable to make a note or open a book, Galileo dictated his new interpretation of certain passages that had always given students of Euclid problems. He still remembered his old friends Sagredo and Salviati, who had been dead for more than twenty years, because he dictated in dialogue form.
But his strength was not up to it. On the evening of Wednesday 8 January 1642, barely a month before his 78th birthday, Galileo died in his bed. With him were Vincenzio, Torricelli and Viviani, who was to write the first biography of Galileo.
In it he describes the death scene:
"With philosophical and Christian constancy, he [Galileo] rendered his soul to his Creator, sending it forth, as far as we can believe, to enjoy and admire more closely those eternal and immutable marvels, which that soul, by means of weak devices with such eagerness and impatience, had sought to bring near to the eyes of us mortals."128
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