Thus attacked, Galileo prepared to defend himself. The greatest caution was necessary, for Grassi was backed by the powerful party of the Jesuits, who made a great boast of this work.[166] The letters of this period from Prince Cesi and Galileo’s ecclesiastical friends at Rome show that they were very anxious that he should not make the influential order of Jesuits his enemies by a direct collision with them. But as they saw the absolute necessity of a reply, they gave him all sorts of good advice, how to parry the attack without incurring their hatred. They were of opinion that he should not honour an adversary concealed behind a pseudonym with a reply written by himself, but should depute the task to a pupil, or, if he intended to conduct his defence in person, clothe his reply in the form of a letter instead of a treatise, not addressed to Sarsi himself, but to one of his own party.[167] He decided for the latter; and adopting a hint from Mgr. Ciampoli,[168] he addressed the reply to Mgr. Cesarini, one of his most devoted friends and dauntless defenders. But the completion of this afterwards famous rejoinder was delayed for two years, and its publication, which, according to custom with all works by members of the Accadémia dei Lincei, was undertaken by the Society, was delayed fully another year owing to the scruples of Prince Cesi and other “lynxes.” Galileo’s procrastination is to be explained partly by his continued ill health, but more so by the position of affairs at Rome as well as in Tuscany, which was by no means encouraging for a contest with a Jesuit.