Having developed a more powerful telescope than others of his day, Galileo made important new observations about the moons of Jupiter, the phases of Venus, and spots on the sun that undermined Ptolemy and were consistent with Copernican theory. Galileo took these observations to the Jesuits, who were among the leading astronomers of the day, and they agreed with him that his sightings had strengthened the case for heliocentrism. The Jesuits told Galileo that the church was divided, with many clergy supporting Ptolemy but others holding that Copernicus was right. Even so, the Jesuits concluded that the question was still open and they did not think that Galileo had clinched the case. Tyco Brahe, the greatest astronomer of the period, agreed that Galileo’s proofs were insufficient and continued to support the geocentric theory. So great was Brahe’s reputation that it prevented the conversion of many astronomers to Copernicanism until after his death.
It may surprise some readers to find out that the pope was an admirer of Galileo and a supporter of scientific research that at the time was conducted mostly in church- sponsored observatories and universities. So was the head of the Inquisition, the learned theologian Cardinal Robert Bellarmine. When Galileo’s lectures supporting the heliocentric theory were reported to the Inquisition, most likely by one of Galileo’s academic rivals in Florence, Cardinal Bellarmine met with Galileo. This was not normal Inquisition procedure, but Galileo was a celebrity. In 1616 he came to Rome with great fanfare, where he stayed at the grand Medici villa, met with the pope more than once, and attended receptions given by various bishops and cardinals.
What Bellarmine observed in connection with Galileo is both memorable and telling. “While experience tells us plainly that the earth is standing still,” Bellarmine wrote, nevertheless “if there were a real proof that the sun is in the center of the universe… and that the sun does not go round the earth but the earth round the sun, then we should have to proceed with great circumspection in explaining passages of scripture which appear to teach the contrary, and rather admit that we did not understand them than declare an opinion to be false which is proved to be true. But this is not a thing to be done in haste, and as for myself, I shall not believe that there are such proofs until they are shown to me.”
This is a model of sensible procedure. Bellarmine assumed that there could be no real conflict between nature and scripture, which is what Christianity has always taught. Consequently, he argued, if we have been reading scripture one way and the natural evidence shows that we were wrong, then we need to revise our interpretation of scripture and acknowledge our mistake. But first let us make sure that there is in fact conclusive scientific proof before we start changing scriptural interpretations that have been taught for a very long time. Bellarmine proposed a solution. Given the inconclusive evidence for the theory and the sensitivity of the religious issues involved, Galileo should not teach or promote heliocentrism. Galileo, a practicing Catholic who wanted to maintain his good standing with the church, agreed. Bellarmine issued an injunction and made a record of the proceeding that went into the church files.
