SOURCE: "Science and Patronage: Galileo and the Telescope," in Isis, Vol. 76, March, 1985, pp. 11-30.

In the following essay, Westfall argues that the heavy reliance upon and competition for patronage in the seventeenth century might have affected the truthfulness of some of the scientific conclusions and discoveries made by scientists of that period, including Galileo.

Sometime late in 1610, probably near 11 December, Galileo received a letter from his disciple Benedetto Castelli:

If the position of Copernicus, that Venus revolves around the sun, is true (as I believe), [Castelli wrote], it is clear that it would necessarily sometimes be seen by us horned and sometimes not, even though the planet maintains the same position relative to the sun…. Now I want to know from you if you, with the help of your marvellous glasses, have observed such a phenomenon, which will be, beyond doubt, a sure means to convince even the...