Altogether the position of affairs seemed remarkably favourable for the publication of the “Dialogues.” Galileo’s devoted adherent, Castelli, had been summoned to Rome in 1624 by Urban VIII., and enjoyed great consideration with the powerful family of Barberini, to whose youngest scion, Taddeo, he gave instruction in mathematics. This long-tried friend informed Galileo in a letter of 6th February,[220] that Father Riccardi, who meanwhile had been raised to the office of chief censor of the press (Magister Sacri Palatii) had promised his ready assistance in Galileo’s affairs. Castelli also expressed his conviction that, as far as Riccardi was concerned, he would find no difficulty. Another piece of information in the same letter, however, was not quite so satisfactory; the personage second in importance at the papal court, Urban’s brother, Cardinal Antonio Barberini, had, when Castelli told him of the completion of the “Dialogues,” said nothing particular against the theory itself, so far as it was treated as a hypothesis, but had made the just remark that the earth, if it revolved round the sun, must be a star, an idea “which was too far opposed to theological truth.” Castelli appeased the cardinal by assuring him that Galileo had weighty arguments against this, and it is characteristic of the prevailing confusion of ideas on astronomical subjects, that Barberini thought this possible, and that Castelli wrote to Galileo that he would not find it hard to steer clear of this rock. Another instance of the trammels placed by religion on the advancement of science.