The Letter to Grand Duchess Christina by Galileo Galilei was an essay on the relation between the revelations of the Bible and the new discoveries then being made in science.
Christina, daughter of Charles II of Lorraine and granddaughter of Catherine de Medici, was the widow of Ferdinando I de Medici, Grand Duke of Tuscany 1587-1609, who had appointed Galileo to the professorship of mathematics at the University of Pisa in 1588.
Late in 1613, Galileo's former student Benedetto Castelli, a Benedictine monk, wrote to Galileo about the events at a recent dinner with the Grand Duke. In the course of conversation at the dinner Cosimo Boscaglia, a professor of philosophy, argued that the motion of the Earth could not be true, being contrary to the Bible. After dinner ended, Castelli was called back to answer scriptural arguments against the motion of the Earth from Christina. The monk took on the role of theologian in response, and convinced everyone there except the Duchess (who he thought was arguing mainly to hear his answers) and Boscaglia (who said nothing during this dialogue).
Galileo replied with a long letter giving his position on the relation between science and Scripture. By 1615, with the controversy over the Earth's motion widespread and increasingly dangerous, Galileo revised this letter and greatly expanded it; this became the Letter to the Grand Duchess Christina. The letter circulated in manuscript but was not printed until much later, when the Inquisition had condemned Galileo. It appeared in Strasbourg in 1636 with both Italian and Latin text. It was suppressed in Catholic jurisdictions, as were all works of Galileo at that time.
[Actual summary of book needed still.]
