His _Delle Macchie Solari_ (1611) brought on a sharp contest over the question of priority of discovery between him and the Jesuit father, Christopher Scheiner of Ingolstadt, from which Galileo emerged victorious and more disliked than before by that order. Opposition was becoming active; Father Castelli, for instance, the professor of mathematics at Pisa and Galileo's intimate friend, was forbidden to discuss in his lectures the double motion of the earth or even to hint at its probability. This same father wrote to his friend early in December, 1613, to tell him of a dinner-table conversation on this matter at the Tuscan Court, then wintering at Pisa. Castelli told how the Dowager Grand Duchess Cristina had had her religious scruples aroused by a remark that the earth's motion must be wrong because it contradicted the Scriptures, a statement that he had tried to refute.[237] Galileo wrote in reply (December 21, 1613), the letter[238] that was to cause him endless trouble, in which he marked out the boundaries between science and religion and declared it a mistake to take the literal interpretation of passages in Scripture that were obviously written according to the understanding of the common people. He pointed out in addition how futile the miracle of the sun's standing still was as an argument against the Copernican doctrine for, even according to the Ptolemaic system, not the sun but the _primum mobile_ must be stayed for the day to be lengthened. [Footnote 237: Fahie: 149.] [Footnote 238: Galileo: _Opere_, V, 281-288.] Father Castelli allowed others to read and to copy this supposedly private letter; copies went from hand to hand in Florence and discussion ran high. On the fourth Sunday in December, 1614, Father Caccini of the Dominicans preached a sermon in the church of S.M. Novella on Joshua's miracle, in which he sharply denounced the Copernican doctrine taught by Galileo as heretical, so he believed.[239] The Copernicans found a Neapolitan Jesuit who replied to Caccini the following Sunday from the pulpit of the Duomo.[240] [Footnote 239: Doc. in Favaro: 48-49.] [Footnote 240: Doc. in Favaro: 49.]