The debate was one-sided and bitter, and the Friends only retired at last on condition of having another opportunity to vindicate themselves. But as Vincent plainly showed that he had no intention of redeeming his promise, the only satisfaction left was the press. In "The Sandy Foundation Shaken," Penn gave the public his view of the matter. But he did not stop with the doctrine of the Trinity, he went on to the Atonement. He advanced such arguments against "Imputed Righteousness" as Barclay has elaborated in his Apology. He also produced arguments against the method in which in those days the necessity of a satisfaction to the Divine justice was taught. His expressions unfortunately resemble those of modern Unitarians, but his position is vitally different. Penn believed the death of Our Saviour on the cross a real Sacrifice, that "Jesus Christ was our holy sacrifice, atonement and propitiation, that he bore our iniquities," but that Christ is not the cause but the effect of God's love. (See his "Primitive Christianity revived.") This book brought down on Penn the anger of Dr. Sanderson, Bishop of London, and led to his being sent to the Tower. But that only "added one more glorious book to the literature of the Tower," "No Cross, No Crown," of which Hepworth Dixon, more trustworthy in literature than in religion, says, "Had the style been more condensed, it would have been well entitled to claim a high place in literature." Whilst there he also replied in a treatise entitled "Innocency with her open face," to many strictures on the "Sandy Foundation Shaken." This imprisonment revealed in two ways the stuff of which William Penn was made. First severity was tried, and one day his servant brought him the report that the bishop was determined he should recant or die in prison. He only smiled and said, "They are mistaken in me; I value not their threats. I will weary out their malice. Neither great nor good things were ever attained without loss and hardship." Then they sent Stillingfleet, the future bishop, to try his powers of persuasion, but they, too, utterly failed. "Tell my father, who I know will ask thee, that my prison shall be my grave before I will budge a jot, for I owe my conscience to no mortal man." Such spirit, combined with the ability his books were revealing, revived the admiral's pride in his son. The court, too, began to take interest in him, and shortly after Stillingfleet's visit he was released, having been in the Tower more than eight months. He at once resumed his preaching, and having been partially reconciled to his father, was employed by him to attend to his Irish estates. On his return home, his father received him fully into his favour, to the great delight of his mother's heart.