SOURCE: "Bellarmino, Galileo, and the Clash of Two World Views," in Essays on the Trial of Galileo, Vatican Observatory Publications, 1989, pp. 1-30.

In the following essay, Westfall summarizes the backgrounds of Galileo and his adversary, Cardinal Bellarmino (also known as Bellarmine), and argues that their conflict regarding Galileo's officially heretical belief in a Copernican or heliocentric universe began as early as 1610 with the publication of Sidereus nuncius (The Starry Messenger).

And because it has also come to the attention of the aforementioned Sacred Congregation [the final paragraph of a decree of 5 March 1616 by the Congregation of the Index stated] that the Pythagorean doctrine concerning the mobility of the earth and the immobility of the sun, which Nicholas Copernicus, De revolutionibus orbium coelestium, and Diego de Zùñiga [in his commentary] on Job also taught, and which is false and altogether incompatible with divine Scripture, is now spread abroad...