Thus Bodies in Water not only challenged Artistotelian physics on the behaviour of submerged or floating objects but also defaced the perfect body of the Sun. Galileo further flouted academic tradition by writing Bodies in Water in Italian, instead of the Latin lingua franca that enabled the European community of scholars to communicate among themselves.
‘I wrote in the colloquial tongue because I must have everyone able to read it,’ Galileo explained – meaning the shipwrights he admired at the Venetian Arsenale, the glassblowers of Murano, the lens grinders, the instrument makers, and all the curious compatriots who attended his public lectures. ‘I am induced to do this by seeing how young men are sent through the universities at random to be made physicians, philosophers, and so on; thus many of them are committed to professions for which they are unsuited, while other men who would be fitted for these are taken up by family cares and other occupations remote from literature…Now I want them to see that just as Nature has given to them, as well as to philosophers, eyes with which to see her works, so she has also given them brains capable of penetrating and understanding them.’
Galileo’s behaviour enraged and insulted his fellow philosophers – especially those, like Ludovico delle Colombe of the Florentine Academy, who had tussled with him in public and lost. Colombe declared himself ‘anti-Galileo’ in response to Galileo’s anti-Aristotelian stance. Supporters of Galileo, in turn, took up the title ‘Galileists’ and further deflated Colombe’s flimsy philosophy by playing derisively on his name. Since colombe means ‘doves’ in Italian, they dubbed Galileo’s critics ‘the pigeon league’.
[V] In the very face of the Sun
IT IS DIFFICULT TODAY – from a vantage point of insignificance on this small planet of an ordinary star set along a spiral arm of one galaxy among billions in an infinite cosmos – to see the Earth as the centre of the universe. Yet that is where Galileo found it.
The cosmology of the sixteenth and seventeenth centuries, founded on the fourth-century-BC teachings of Aristotle and refined by the second-century Greek astronomer Claudius Ptolemy, made Earth the immobile hub. Around it, the Sun, the Moon, the five planets and all the stars spun eternally, carried in perfectly circular paths by the motions of nested crystalline celestial spheres. This heavenly machinery, like the gearwork of a great clock, turned day to night and back to day again.
In 1543, however, the Polish cleric Nicolaus Copernicus flung the Earth from its central position into orbit about the Sun, in his book On the Revolutions of the Heavenly Spheres, or De revolutionibus, as it is usually called. By imagining the Earth to turn on its own axis once a day, and travel around the Sun once a year, Copernicus rationalised the motions of the heavens. He saved the enormous Sun the trouble of traipsing all the way around the smaller Earth from morning till evening. Likewise the vast distant realm of the stars could now lie still, instead of having to wheel overhead even more rapidly than the Sun every single day. Copernicus also called the planets to order, relieving those bodies of the need to coordinate their relatively slow motion towards the east over long periods of time (Jupiter takes twelve years to traverse the twelve constellations of the zodiac, Saturn thirty) with their speedy westwards day trips around the Earth. Copernicus could even explain the way Mars, for example, occasionally reversed its course, drifting backwards (westwards) against the background of the stars for months at a time, as the logical consequence of heliocentrism: the Earth occupied an inside track among the paths of the planets – third from the Sun, as opposed to Mars’s fourth position – and could thus overtake the slower, more distant Mars every couple of years.
Copernicus, who studied astronomy and mathematics at the University of Cracow, medicine for a while in Padua and canon law in Bologna and Ferrara, devoted most of his life to cosmology, thanks to nepotism. When he returned to Poland from his studies in Italy at the age of thirty, his uncle, a bishop, helped secure Copernicus a lifetime appointment as a canon at the cathedral of Frombork. Serving forty years in that ‘most remote corner of the Earth’, with manageable duties and a comfortable pension, Copernicus created an alternative universe.
‘For a long time I reflected on the confusion in the astronomical traditions concerning the derivation of the motion of the spheres of the Universe,’ Copernicus wrote in Frombork. ‘I began to be annoyed that the philosophers had discovered no sure scheme for the movements of the machinery of the world, created for our sake by the best and most systematic Artist of all. Therefore, I began to consider the mobility of the Earth and even though the idea seemed absurd, nevertheless I knew that others before me had been granted the freedom to imagine any circles whatsoever for explaining the heavenly phenomena.’
Although he made numerous naked-eye observations of the positions of the planets, most of Copernicus’s lonely work involved reading, thinking and mathematical calculations. He proffered no supporting evidence of any kind. And nowhere, alas, did he record the train of thought that led him to his revolutionary hypothesis.
An anonymous introductory note to Copernicus’s book dismissed the whole conceit as merely an aid to computation. The complex business of determining the orbital periods of the planets, including the Sun and Moon, figured crucially in establishing the length of the year and the date of Easter. Copernicus himself, writing in the languages of Latin and mathematics for a scholarly audience, never attempted to convince the general public that the universe was actually constructed with the Sun at the centre. And who would have believed him if he had? The fact that the Earth remained motionless was a truism, obvious to any sentient individual. If the Earth rotated and revolved, then a ball tossed into the air would not fall right back into one’s hands but land hundreds of feet away, birds in flight might lose the way to their nests, and all humanity suffer dizzy spells from the daily spinning of the global carousel at one thousand miles per hour.*
‘The scorn which I had to fear’, Copernicus remarked in De revolutionibus, ‘on account of the newness and absurdity of my opinion almost drove me to abandon a work already undertaken.’ Continuous calculation and checking delayed publication of his manuscript for decades, until he lay literally on his deathbed. Expiring at the age of seventy, immediately after the first printing of his book in 1543, Copernicus avoided any brush with derision.
When Galileo ascended the wooden steps of his teaching platform at Padua to lecture on planetary astronomy, beginning in 1592, he taught the Earth-centred view, as it had been preserved from antiquity. Galileo knew of Copernicus’s challenge to both Aristotle and Ptolemy, and he may have casually mentioned this alternative idea to his students, too. Heliocentrism, however, played no part in his formal curriculum, which was primarily concerned with teaching medical students how to cast horoscopes. Nevertheless, Galileo gradually convinced himself that the Copernican system not only looked neater on paper but was likely to hold true in fact. In a 1597 letter he wrote to a former colleague at Pisa, Galileo assessed the system of Copernicus as ‘much more probable than that other view of Aristotle and Ptolemy’. He expressed the same faith in Copernicus in a letter he wrote to Kepler later that year, regretting how ‘our teacher Copernicus, who though he will be of immortal fame to some, is yet by an infinite number (for such is the multitude of fools) laughed at and rejected’. Since the Copernican system remained just as absurd to popular opinion fifty years following its author’s demise, Galileo long maintained his public silence on the subject.
In 1604, five years prior to Galileo’s development of the telescope, the world beheld a never-before-seen star in the heavens. It was called ‘nova’ for its newness.* It flared up near the constellation Sagittarius in October and stayed so prominent through November that Galileo had time to deliver three public lectures about the newcomer before it faded from bright view. The nova challenged the law of immutability in the heavens, a cherished tenet of the Aristotelian world order. Earthly matter, according to ancient