1 Italians counted days from sunset before the calendar reform of 1582, and Galileo recorded his date of birth as follows: 15 February at 22.30 hours. The Sun set at 5.30 p.m. on that day according to our modern way of reckoning, which means that he was born on 16 February at 4.00 p.m.
2 Viviani wrote a Historical Account of the Life of Galileo in the form of a letter to Prince Leopold de’ Medici in 1654, twelve years after Galileo’s death (Galileo, Opere, 19, p. 606).
3 See William R. Shea, Galileo’s Intellectual Revolution (New York: Science History Publications, 1977), 173.
4 Copernicus’ On the Revolutions of the Heavenly Spheres had appeared in 1543, but heliocentrism was generally considered a mere conjecture rather than a probable fact until Kepler published his Cosmographic Mystery in 1597.
6 Opere, 7, p. 486; p. 356 in this volume.
7 Letter to Paolo Sarpi, 16 October 1604 (Opere, 10, p. 115).
8 Actually the telescope had been invented in Italy around 1590. On the technology and the problems involved, see Galileo’s Sidereus Nuncius or A Sidereal Message, translated from the Latin by William R. Shea. Introduction and Notes by William R. Shea and Tiziana Bascelli (Sagamore Beach, Mass.: Science History Publications, 2009).
11 Opere, 10, p. 353.
12 Letter to Galileo of 13 August 1611 (Opere, 11, p. 171).
13 Letter of Galileo to a correspondent in Florence in February 1619 (Opere, 10, p. 233).
pp. 237–8; p. 53 in this volume).
16 Letter of 31 May 1611 (Opere, 11, p. 119).
17 This is a reference to the famous Greek painter Apelles (fourth century BC) who is said to have hidden behind his paintings to hear the comments of passers-by. When a cobbler found fault with sandals he had drawn Apelles made the corrections that very night. Next morning the cobbler was so proud that he began to criticize how Apelles portrayed the leg, whereupon the painter emerged from his hiding-place and said: ‘Shoemaker, don’t judge above the sandal!’ The source is Pliny’s Natural History, 35.85.
19 Letter of Niccolò Lorini, 5 November 1612 (Opere, 11, p. 427).
21 Letter of Giovanni Ciampoli to Galileo, 28 February 1615 (Opere, 12, p. 146).
23 See p. 70 in this volume.
24 On Foscarini’s book see the note to p. 94 below.
pp. 94–6 in this volume. ‘Saving the appearances’ was frequently used in Galileo’s day to indicate the common view that astronomical theories were mere geometrical devices put forward for the sake of calculation and not as a representation of physical reality.
27 Minutes of the meeting of 24 February 1616 (Opere, 19, p. 321).
29 See p. 115 in this volume.
30 An Agnus Dei is the name given to discs of wax impressed with the figure of a lamb and blessed at stated seasons by the Pope. The lamb usually bears a cross or flag, and a figure or the name and arms of the Pope are commonly impressed on the reverse. They are made of the remnants of the preceding year’s paschal candle, and in the Middle Ages the Popes sent them as presents to sovereigns and distinguished personages. They were considered a protection against blights and tempests. In the penal laws of Queen Elizabeth Agni Dei are mentioned among ‘popish trumperies’, the importation of which into England was strictly forbidden.
pp. 134–5). On the Morandi affair, see Brendan Dooley, Morandi’s Last Prophecy and the End of Renaissance Politics (Princeton: Princeton University Press, 2002).
32 As reported by Benedetto Castelli in his letter to Galileo, 21 September 1630 (Opere, 14, p. 150).
33 This was said to the Tuscan Ambassador, Francesco Niccolini, who mentions it in his letter to the Secretary of State in Florence, 5 September 1632 (Opere, 14, p. 384).
34 Account given by Giovanfrancesco Buonamici in 1633 (Opere, 19, p. 410).
35 Opere, 7, p. 489; p. 358 in this volume.