The Sleepwalkers: A History of Man's Changing Vision of the Universe

by Arthur Koestler

This was in November 1615. For the next eighteen years Galileo lived honoured and unmolested, befriended by Pope Urban VIII and an impressive array of cardinals. But the Letters to Castelli and to the Grand Duchess remained on the files of the Inquisition, and in the minds of the theologians. The text was so carefully worded that it could not be indicted as heresy, but the intent was unmistakable; it constituted a challenge which sooner or later had to be answered. The challenge lay in the implied claim that the Copernican system belonged to the category of ‘rigorously demonstrated’ physical truths to which the meaning of the Bible must be adapted; and that unless it was explicitly refuted and condemned, theological objections would become irrelevant and the case would go by default.