Writing to Christina, the grand duchess of Tuscany, Galileo recalls the controversy his writings in astronomy stirred up some years ago because they contradicted commonly held notions about the physical universe. Some scholars responded by attacking Galileo in print with “vain arguments” backed up with passages from the Bible, “which they had failed to understand properly, and which were ill suited to their purposes” (175). These critics were not merely hostile to Galileo’s discoveries but seemed to harbor a “reckless passion” against Galileo himself, and they enacted “calumnies and persecutions” (176) against him.

Normally, Galileo would simply laugh these incidents off, confident that truth would win out in the end. However, he feels compelled to respond for several reasons. First, his attackers are charging him with religious heresy—something that he finds “abhorrent.” Second, some critics do not understand the science. Third, such attacks could influence public opinion in disfavor of science and mathematics in general and of professionals in these disciplines. Some of Galileo’s opponents even imply that science as such is inimical to religion—something with which Galileo strongly disagrees. In addition, the personal attacks against Galileo are misplaced because he is simply carrying on the thought of Nicholas Copernicus—a scientist who in his day was respected by the Catholic Church and was himself a member of the clergy.