Page:The Gradual Acceptance of the Copernican Theory of the Universe.djvu/71

 with the accession to the papacy in 1623 of Cardinal Barberini, as Urban VIII, a warm admirer and supporter of his, he thought relief was in sight. He was further cheered by a conversation Cardinal di Zollern reported having had with Pope Urban, in which his Holiness had reminded the Cardinal how he (the Pope) had defended Copernicus in the time of Paul V, and asserted that out of just respect owed to the memory of Copernicus, if he had been pope then, he would not have permitted his opinion to be declared heretical. Feeling that he now had friends in power, Galileo began his great work, Dialogo sopra i Due Sistemi Massimi del Mondo, a dialogue in four "days" in which three interlocutors discuss the arguments for and against the Copernican theory, though coming to no definite conclusion. Sagredo was an avowed Copernican and Galileo's spokesman, Salviati was openminded, and the peripatetic was Simplicio, appropriately named for the famous Sicilian sixth century commentator on Aristotle.

In 1630 he brought the completed manuscript to Riccardi, Master of the Sacred Palace, for permission to print it in Rome. After much reading and re-reading of it both by Ricardi and his associate, Father Visconti, permission was at length granted on condition that he insert a preface and a conclusion practically dictated by Riccardi, emphasizing its hypothetical character. The Pope's own argument was to be used: "God is all-powerful; all things are therefore possible to Him; ergo, the tides cannot be adduced as a necessary proof of the double motion of the earth without limiting God's omnipotence—which is absurd." Galileo returned to Florence in June with the permission to print his book in Rome. Meanwhile the plague broke out. He decided to print it in Florence instead, and on writing to Riccardi for that permission, the latter asked for the book to review it again. The times were too troublesome to risk sending it, so a compromise was finally effected: Galileo was to send the preface and conclusion to Rome and Riccardi agreed to instruct the Inquisitor at Florence as to his requirements and to authorize him to license the book. The parts were not returned from

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