The Copernican System Versus Holy Scripture

chapter 5 The Copernican System versus Holy Scripture

The Spectre of Giordano Bruno

The first signs of Galileo’s concern at the denunciations of the incompatibility of the Copernican system with Holy Scripture emerge from the reply of Cardi- nal Carlo Conti on 7 July 1612 to a (lost) letter of the Tuscan scientist.1 The Car- dinal, who was on friendly terms with Cesi, was answering Galileo’s question as to ‘whether Holy Scripture supports the principles of Aristotle on the consti- tution of the universe’. Before giving his opinion, the Cardinal pointed out the need to focus on the precise significance of the Tuscan scientist’s query: was he referring to ‘the incorruptibility of the heavens, as his letter seemed to suggest in stating that new phenomena are discovered in the sky every day’, or to the ‘two motions of the Earth’?2 Conti’s position on the first point was peremptory:

There can be no doubt that Scripture does not support Aristotle; indeed it tends rather to the opposite, as it was the common opinion of the Fathers that the heavens were corruptible.3

1 Galileo presumably sent his questions to Cardinal Conti from Florence at the end of June. 2 og xi, p. 354. On Galileo’s relations with the Cardinal and on the Cardinal’s letter of 7 July 1612, see Poppi 1996–1997. Poppi’s article contains a careful analysis of the sources used by Galileo to write the Copernican letters and the development of his strategy to confront the accusations of incompatibility between the Copernican conceptions and Holy Scrip- ture. According to Poppi’s analysis, Galileo had adopted a substantially concordist strategy in the Letters on sunspots, but replaced it in the Copernican Letters with the claim of the independence of the Book of Nature from Holy Scripture. Poppi disagrees with Vincenzo Ferrone, according to whom Galileo’s discussions with Cesi in Rome in 1611 and their correspondence in the immediately successive years contributed significantly to defining the way in which he dealt with Holy Scripture in his Copernican Letters (Ferrone 1984, pp. 247–53). Ferrone’s suggestion should be borne in mind in reconstructing the Tuscan scientist’s shift from the instrumentally concordist positions of the Letters on sunspots to claiming the full autonomy of natural philosophy from theology and Holy Scripture in the Copernican Letters, in general, and in the Letter to Benedetto Castelli in particular. 3 og xi, p. 354.

He was, however, more cautious as to whether the novelties discovered in the sky demonstrated its corruptible nature. Referring to the sunspots, Conti stressed that they could not be considered conclusive proof since it was possible to advance interpretations, such as that of Scheiner, that saved the incorrupt- ible nature of the Sun.4 The Cardinal urged Galileo to exercise prudence on this point and above all to consider the uncertainty of human knowledge. The sense of his message was clear: the thesis of the corruptible heavens was plausible and even authoritative, not because it was suggested by telescopic observation of celestial bodies and phenomena, but because it had the backing of Holy Scripture. The second horn of the dilemma, the motions of the Earth, seemed to Conti less in accordance with Scripture. He underlined the opposition to it of all the Church Fathers with the exception of the commentary on the Book of Job by Diego da Stunica, ‘although his interpretation is not generally followed’. The only way to reconcile the Copernican vision with Holy Scripture would be to maintain that the sacred texts speak ‘to be understood by the common people’. He stressed, however, that this kind of interpretation should not be admitted ‘unless under great necessity’.5 Conti was aware of the latest celestial discovery, that of the sunspots, and he had read Scheiner’s Tres epistulae.6 Like Cesi and Bellarmine, he was convinced that the heavens were fluid; but he hesitated, as did Federico, before the Co- pernican hypothesis. His position was similar to that of many other prelates and natural philosophers, not only on the Roman scene, after the shockwave

4 In his successive letter to Galileo of 18 August, Conti mentioned again that he considered plausible Scheiner’s hypothesis according to which, as small planets cross the Sun they produce shadows that to us on Earth look like dark spots: ‘It might be argued […] that those spots – the Cardinal wrote – are produced by stars so minute that no gaps can be seen between them, and that their mass produces the appearance of those spots, and that they are so many in number and have such diverse movements around the Sun that, by conjoining in different shapes, they produce that diversity of spots […]’ (ibid., p. 376). It should be noted that Cesi had told Galileo that Scheiner’s interpretation of the spots was finding favour in Roman circles: ‘The Peripatetics all jump at it, nor are they ashamed to say that those invisible little stars are fixed in some tiny spheres or rather celestial crusts, which conjoin and disjoin in their movements, because they are just as reluctant to lose the diamantine solidity of the heavens as the privilege of incorruptibility’ (cl, p. 284, letter of 3 November 1612). Federico took a dim view of Scheiner’s interpretation and invited Galileo to examine and refute it. Galileo welcomed the Prince’s proposal. He sar- castically demonstrated the weakness of Scheiner’s hypothesis in the third of his Letters on sunspots (Galilei-Scheiner 2010, pp. 291ff.: og v, pp. 231ff.). 5 Ibid., pp. 354–5. 6 Scheiner 1612.