It was not long, however, before the admiral relented, owing chiefly to her efforts in his behalf, and allowed him to return home, though still refusing to see or hold any communication with him. It must indeed have been a crushing blow to the proud and ambitious man of the world to have his son and heir travelling about the country as a poor preacher, for it was about this time, 1668, that William first began to preach. He also utilized his learning and talents by writing in defence of the new doctrines he had embraced. One of these publications, entitled “The Sandy Foundation Shaken,” attracted much attention. In it he cleverly attempted to prove that certain fundamental doctrines of the established church were contrary to Scripture—a heresy for which the Bishop of London had him imprisoned. Indeed his malicious enemies went so far as to claim that Penn had dropped a letter at the time of his arrest, written by himself and containing treasonable matter, but although his innocence on this point was soon established, he was forced, nevertheless, to remain for nine months in the Tower. Even the King, to whom Sir William appealed on his son’s behalf, did not dare to intervene for fear of increasing the suspicion, in which he already stood, of being an enemy to the church. All he could do was to send the court chaplain to visit Penn and urge him to make amends to the irate Bishop, who was determined he should publicly retract his published statements or end his days in prison. But this the young enthusiast refused to do, replying with the spirit of a martyr that his prison should be his grave before he would renounce his just opinions; that for his conscience he was responsible to no man.