An accidental circumstance, however, was the immediate cause of turning the controversy into the channel which proved so fatal to Galileo. One day in December, 1613, Castelli and several other learned men were guests at the Grand Duke’s table at Pisa, where the court was then staying. The conversation turned chiefly on the remarkable phenomena of the Medicean stars, whose veritable existence in the heavens Boscaglia, professor of physics at the university, was constrained with a heavy heart to confirm, in answer to a question of the Grand Duke’s mother, Christine. Castelli eagerly seized the opportunity of applauding Galileo’s splendid discovery. Boscaglia, a Peripatetic of the purest water, could not master his displeasure, and whispered meanwhile to the Grand Ducal mother that all Galileo’s telescopic discoveries were in accord with the truth, only the double motion of the earth seemed incredible, nay impossible, as the Holy Scriptures were clearly opposed to it. The repast was then over, and Castelli took leave; but he had scarcely left the palace when he saw Christine’s porter hastening after him and calling him back. He obeyed, and found the whole company still assembled in the Grand Duke’s apartments. Christine now began, after a few introductory remarks, to attack the Copernican doctrines, appealing to Holy Scripture. Castelli at first made some humble attempts to avoid bringing the Bible into the controversy; but as this was of no avail he resolutely took the theological standpoint, and defended the modern views of the universe so impressively and convincingly that nearly all present, even the Grand Duke and his consort, took his side, and the Duchess dowager alone made any opposition. Boscaglia, however, who had been the cause of the unedifying scene, took no part whatever in the discussion. Castelli hastened to apprise Galileo of this incident, but remarked expressly in his striking letter that it appeared to him that the Grand Duchess Christine had merely persisted in opposition, in order to hear his replies.[90]