presumably because he was known to have influential friends at the Vatican. The Inquisition tried to obtain the original letter but failed to do so, and the copy was submitted to expert opinion, which pronounced that on the whole the document could not be said to belie Catholic doctrine. Accordingly fresh evidence against Galileo was sought, and it was alleged that his religious opinions were suspect, because he was in correspondence with Germans and others, possibly heretics, and was a member of the Academy "dei Lincei". Galileo heard that his letter to Castelli was being used to secure a condemnation of the Copernican doctrine, so he sent a copy to Rome to be submitted to Cardinal Bellarmine and other prominent men, promising to follow it with a fuller treatise, since the first letter was only written on the spur of the moment. His friends, including Prince Cesi, founder of the Academy "dei Lincei," recommended him to avoid theology altogether in his argument about mathematical and physical matters, but the advice was already too late. The promised fuller treatise, the letter to the Grand Duchess Cristina, would not affect the position, as the Inquisition was already preparing its attack in secret, based on the evidence already received. Galileo, not knowing how far things had gone, thought his best plan would be a personal visit to Rome, remembering, how well he had been received on his first journey thither. He went accordingly in December, 1615, but, though cordially received to all appearance, he soon found the task of defence a bigger one than he had expected, as he himself as well as the doctrines was being attacked. It might have been well for him to confine himself to the personal attacks as he might have succeeded in disposing of them. But he felt bound to persevere with his efforts on behalf of the Copernican theory, after obtaining apparently satisfactory assurance
