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Paolo Sarpi and the first Copernican tidal theory

  • RON NAYLOR (a1)

Despite his demanding religious responsibilities, Paolo Sarpi maintained an active involvement in science between 1578 and 1598 – as his Pensieri reveal. They show that from 1585 onwards he studied the Copernican theory and recorded arguments in its favour. The fact that for 1595 they include an outline of a Copernican tidal theory resembling Galileo's Dialogue theory is well known. But examined closely, Sarpi's theory is found to be different from that of the Dialogue in several important respects. That Sarpi was a Copernican by 1592 is revealed by other of his pensieri, whereas at that time we know that Galileo was not. The examination of Sarpi's tidal theory and of the work of Galileo in this period indicates that the theory Sarpi recorded in 1595 was of his own creation. The appreciation that the theory was Sarpi's and that Galileo subsequently came to change his views on the Copernican theory and adopted the tidal theory has major implications for our understanding of the significance of Sarpi's contribution to the Scientific Revolution. Moreover, it appears that several of the most significant theoretical features of the tidal theory published by Galileo in the Dialogue – and which proved of lasting value – were in reality Sarpi's.

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1 Socio, Libero, ‘I Pensieri di Paolo Sarpi sul moto’, Studi veneziani (1971) 13, pp. 328329, 349–352. That Sarpi studied Copernicus at this time is also the conclusion of Heilbron, John L. in Galileo, Oxford: Oxford University Press, 2010, p. 81; and that he became a convinced Copernican is the view of Wootton, David, Paolo Sarpi, between Renaissance and Enlightenment, Cambridge: Cambridge University Press, 1983, p. 18.

2 Sarpi, Paulo, Pensieri Naturali, Metafisici e Matematici (ed. Cozzi, Luisa and Sosio, Libero), Milan: Riccardi, 1996, pensieri 568–571, pp. 423–426.

3 Sarpi, op. cit. (2), pensieri 499 and 505, pp. 366–367, 370.

4 Cesalpino, Andrea, Quaestionum peripateticarum libri V, Venice: Iuntas, 1571, 70r–71v.

5 Galilei, Galileo, Le Opere de Galileo Galilei (ed. Favaro, A.), 20 vols., Florence: Barbera 1890–1909, vol. 10, p. 68.

6 Sarpi, op. cit. (2), pensiero 568, p. 423.

7 Here Sarpi identified a symmetry but his cryptic style has led to it being overlooked; Drake misunderstood Sarpi's reference to the Moon. See Drake, Stillman, Galileo Studies, Michigan: University of Michigan Press, 1970, p. 201.

8 Sarpi, op. cit. (2), pensiero 571, p. 426.

9 Galileo, op. cit. (5), vol. 5, p. 381; Finocchiaro, Maurice A., The Galileo Affair: A Documentary History, Berkeley: University of California Press, 1989, p. 122. Drake, op. cit. (7), p. 254.

10 Drake, op. cit. (7), pp. 201–204. Drake, , Galileo: Pioneer Scientist, Toronto: University of Toronto Press, 1990, p. 72.

11 Sarpi, op. cit. (2), CLVI–CLVII. Folsing, Albrecht followed Drake in Galileo Galilei, Prozess ohne Ende, Munich: Piper Verlag, 1983, pp. 160161. Others following Drake's view include Sharratt, Michael, Galileo: Decisive Innovator, Cambridge: Cambridge University Press, 1996, p. 71; Fantoli, Annibal, Galileo for Copernicanism and for the Church, Rome: Vatican Observatory Publications, 1996, p. 68; Renn, Jurgen, Damerow, Peter and Reiger, Simone, ‘Hunting the white elephant: when and how did Galileo discover the law of fall?’, Science in Context (2000) 13, pp. 299423, 350; Wootton, op. cit. (1), pp. 62–63. However, Heilbron, op. cit. (1), pp. 115 and 217, takes the view that Socio and Drake's arguments appear to be equally plausible; Palmieri, Paulo, ‘Re-examining Galileo's theory of tides’, Archive for the History of the Exact Sciences (1998) 53, pp. 229230, regards the issue as open. Socio's strong reasons for rejecting Drake's interpretation are at CLCI–CLIX. Bonelli, Federico and Russo, Lucio, ‘The origin of modern astronomical theories of tides: Chrisogono, de Dominis and their sources’, BJHS (1996) 29, pp. 385401, 398, regard Sarpi as the creator of the theory.

12 Drake, op. cit. (7), p. 202; Sarpi, op. cit. (2), p. 182.

13 Sarpi, op. cit. (2), pp. 290, 477–483, 496. For Socio's discussion of pensiero 401 see CXLVIII–CXLIX.

14 Drake, Stillman, Galileo at Work, London: The University of Chicago Press, 1978, p. 37; Drake, op. cit. (7), p. 204.

15 Drake, op. cit. (7), p. 203; Cozzi, in Sarpi, op. cit. (2), CLVII, who identifies references to Benedetti (twice), Vesalius, Bartoleme de Medina and Agostino da Mula, as well as Galileo and a number of lesser figures like il Panizza and il Valier.

16 Drake, op. cit. (7), p. 203.

17 Drake, op. cit. (7), pp. 201–202.

18 Drake, op. cit. (7), pp. 201–202.

19 Galileo, op. cit. (5), vol. 5, p. 381; Finocchiaro, op. cit. (9), p. 122.

20 Drake, op. cit. (7), p. 203.

21 Drake, op. cit. (7), p. 201.

22 Sarpi, op. cit. (2), CLVII–CLVIII.

23 Sarpi, op. cit. (2), pp. 366, 370.

24 Sarpi, op. cit. (2), p. 401, pensiero 540. The evidence of pensiero 540 reveals that in 1592 Sarpi believed in the Earth's rotation. Galileo did not believe in the Earth's rotation at that time and there is no indication of his influence in any case. Socio and Cozzi maintain that the Pensieri indicate that Sarpi influenced and preceeded Galileo at several points. Renn, Damerow and Reiger argued that the claim that Galileo could have taken ideas from Sarpi is unconvincing in view of the shared sources of their ideas. However, Renn, Damerow and Reiger argue that it is possible to reach the opposite conclusion, that Sarpi was influenced by Galileo, but provide no indication of how that could be done. Thus it is argued that the tidal theory was Galileo's. See Renn, Damerow and Reiger, op. cit. (11), p. 350, and that Sarpi's non-extrusion argument is an anticipation of Galileo's later version, at p. 351 n. 54. However, Cozzi and Socio's interpretation appears more convincing. See Sarpi, op. cit. (2), p. 400. In Socio's subsequent article, ‘Paolo Sarpi, un frate nella rivoluzione scientifica’, Rispensando Paulo Sarpi. Atti del convegnointernationale di studi nel 450 anniversario della nascita di Paolo Sarpi. A cura di Corrado Pin. Ateneo Veneto, 2006, the case is again made for the independence of Sarpi's thought from Galileo's influence. It is argued that Sarpi was effectively a mentor for Galileo in a number of respects.

25 Heilbron, op. cit. (1), p. 217; Wootton, op. cit. (1), pp. 62–63, 149–150.

26 Wootton, op. cit. (1), p. 45.

27 Wootton, op. cit. (1), p. 103.

28 Drake, op. cit. (7), pp. 185–186, indicates that the evidence rules out the possibility that Galileo ever observed the sunspot cycle as he claimed; while Heilbron, op. cit. (1), p. 280, observes that Galileo simply stole Scheiner's observations and the solar theory based on them and made both serve his Copernican cosmology.

29 Galileo, op. cit. (5), vol. 2, p. 549. However, the general view of the significance of Sarpi's influence is probably more typically reflected in Sharratt, op. cit. (11), p. 77, who sees Sarpi as no more than a gifted amateur ‘who was good enough for Galileo to bounce important ideas off’. Even if this is a widely held view others rate his influence as considerable, not only Cozzi and Socio but Galileo's recent biographer Heilbron, who comments, op. cit. (1), p. 80, ‘He was to serve Galileo as a guide post, and a sounding board, and, very probably, as a model.’ Somewhat similar estimations of Sarpi's significance may be found in Reeves, E., Painting the Heavens: Art and Science in the Age of Galileo, Princeton: Princeton University Press, 1997.

30 Cozzi, in Sarpi, op. cit. (2), p. xix, quote from Fabricius, pp. xx, xlii–xliv; Porta, Della, Natural Magick, London: Young and Speed (1658), p. 190. The translations of Fabricius from Cozzi are those of Heilbron, op. cit. (1), p. 80.

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