The duke being now alone with Isabel, commended her virtuous resolution, saying, “The hand that made you fair, has made you good.”  “O,” said Isabel, “how much is the good duke deceived in Angelo! if ever he return, and I can speak to him, I will discover his government.”  Isabel knew not that she was even now making the discovery she threatened.  The duke replied, “That shall not be much amiss; yet as the matter now stands, Angelo will repel your accusation; therefore lend an attentive ear to my advisings.  I believe that you may most righteously do a poor wronged lady a merited benefit, redeem your brother from the angry law, do no stain to your own most gracious person, and much please the absent duke, if peradventure he shall ever return to have notice of this business.”  Isabel said, She had a spirit to do anything he desired, provided it was nothing wrong.  “Virtue is bold, and never fearful,” said the duke:  and then he asked her, if she had ever heard of Mariana, the sister of Frederick, the great soldier who was drowned at sea.  “I have heard of the lady,” said Isabel, “and good words went with her name.”  “This lady,” said the duke, “is the wife of Angelo; but her marriage dowry was on board the vessel in which her brother perished, and mark how heavily this befell to the poor gentlewoman! for, beside the loss of a most noble and renowned brother, who in his love towards her was ever most kind and natural, in the wreck of her fortune she lost the affections of her husband, the well-seeming Angelo; who pretending to discover some dishonour in this honourable lady (though the true cause was the loss of her dowry) left her in her tears, and dried not one of them with his comfort.  His unjust unkindness, that in all reason should have quenched her love, has, like an impediment in the current, made it more unruly, and Mariana loves her cruel husband with the full continuance of her first affection.”  The duke then more plainly unfolded his plan.  It was, that Isabel should go to lord Angelo, and seemingly consent to come to him as he desired, at midnight; that by this means she would obtain the promised pardon; and that Mariana should go in her stead to the appointment, and pass herself upon Angelo in the dark for Isabel.  “Nor, gentle daughter,” said the feigned friar, “fear you to do this thing; Angelo is her husband, and to bring them thus together is no sin.”  Isabel being pleased with this project, departed to do as he directed her; and he went to apprize Mariana of their intention.  He had before this time visited this unhappy lady in his assumed character, giving her religious instruction and friendly consolation, at which times he had learned her sad story from her own lips; and now she, looking upon him as a holy man, readily consented to be directed by him in this undertaking.