Harold, the Last of the Saxon Kings Book X: The Sacrifice on the Altar by Edward Bulwer-lytton

All other thought had given way to Harold's impetuous yearning to throw himself upon the Church, to hear his doom from the purest and wisest of its Saxon preachers. Had the prelate deemed his vow irrefragable, he would have died the Roman's death, rather than live the traitor's life; and strange indeed was the revolution created in this man's character, that he, "so self-dependent," he who had hitherto deemed himself his sole judge below of cause and action, now felt the whole life of his life committed to the word of a cloistered shaveling. All other thought had given way to that fiery impulse -- home, mother, Edith, king, power, policy, ambition! Till the weight was from his soul, he was as an outlaw in his native land.

But when the next sun rose, and that awful burthen was lifted from his heart and his being -- when his own calm sense, returning, sanctioned the fiat of the priest, -- when, though with deep shame and rankling remorse at the memory of the vow, he yet felt exonerated, not from the guilt of having made, but the deadlier guilt of fulfilling it -- all the objects of existence resumed their natural interest, softened and chastened, but still vivid in the heart restored to humanity. But from that time, Harold's stern philosophy and stoic ethics were shaken to the dust; re-created, as it were, by the breath of religion, he adopted its tenets even after the fashion of his age. The secret of his shame, the error of his conscience, humbled him. Those unlettered monks whom he had so despised, how had he lost the right to stand aloof from their control! how had his wisdom, and his strength, and his courage, met unguarded the hour of temptation!