theory. In the final examination, he was threatened with torture. He said that before the decree of 1616 he had held the truth of the Copernican system to be arguable, but since then he had held the Ptolemaic to be true. Next day, he publicly abjured the scientific truth which he had demonstrated. He was allowed to retire to the country, on condition that he saw no one. In the last months of his life he wrote to a friend to this effect: "The falsity of the Copernican system cannot be doubted, especially by us Catholics. It is refuted by the irrefragable authority of Scripture. The conjectures of Copernicus and his disciples were all disposed of by the one solid argument: God's omnipotence can operate in infinitely various ways. If something appears to our observation to happen in one particular way, we must not curtail God's arm, and sustain a thing in which we may be deceived." The irony is evident.
Rome did not permit the truth about the solar system to be taught till after the middle of the eighteenth century, and Galileo's books remained on the Index till 1835. The prohibition was fatal to the study of natural science in Italy.
The Roman Index reminds us of the significance of the invention of printing in the struggle for freedom of thought, by mak-
