The String of Pearls (1850), p. 75

"It might indeed"
"Then it will be unfair to place it upon any one but those who feel most deeply for its success."
"Johanna, the enthusiasm with which you speak awakens in me a thought which I shrink from expressing to you, and which, I fear, perhaps more originates from a certain feeling of romance, which, I believe, is a besetting sin, than from any other cause."
"Name it, Arabella; name it."
"It would be possible for you or I to accomplish the object, by going disguised to the barber's, and accepting such a situation, if it were vacant, for a period of about twenty-four hours, in order that during that time an opportunity might be taken of searching in his house for some evidence upon the subject nearest to your heart."
"It is a happy thought," said Johanna, "and why should I hesitate at encountering any risk, or toil, or difficulty, for him who has risked so much for me? What is there to hinder me from carrying out such a resolution? At any moment, if great danger should beset me, I can rush into the street, and claim protection from the passers-by."
"And moreover, Johanna, if you went on such a mission, remember you go with my knowledge, and that consequently I would bring you assistance, if you appeared not in the specified time for your return."
"Each moment, Arabella, the plan assumes to my mind a better shape. If Sweeney Todd be innocent of contriving anything against the life and liberty of those who seek his shop, I have nothing to fear; but if, on the contrary, he be guilty, danger to me would be the proof of such guilt, and that is a proof which I am willing to chance encountering for the sake of the great object I have in view; but how am I to provide myself with the necessary means?"
"Be at rest upon that score. My cousin Albert and you are as nearly of a size as possible. He will be staying here shortly, and I will secure from his wardrobe a suit of clothes, which I am certain will answer your purpose. But let me implore you to wait until you have had your second interview with Colonel Jeffery."
"That is well thought of; I will meet him, and question him closely as to the personal appearance of this Mr. Thornhill; beside, I shall hear if he has any confirmed suspicion on the subject."
"That is well, you will soon meet him, for the week is running on; and let me implore you, Johanna, to come to me the morning after you have so met him,and then we will again consult upon this plan of operations, which appears to us feasible and desirable."
Some more conversation of a similar character ensued between these young girls; and upon the whole, Johanna Oakley felt much comforted by her visit, and more able to think calmly as well as seriously upon the subject which engrossed her whole thoughts and feelings; and when she returned to her own home, she found that much of the excitement of despair which had formerly had possession of her, had given way to hope; and with that natural feeling of joyousness, and that elasticity of mind which belongs to the young, she began to build in her imagination some airy fabrics of future happiness. Certainly, these suppositions went upon the fact that Mark Ingestrie was a prisoner, and not that his life had been taken by the mysterious barber; for although the possibility of his having been murdered had found a home in her imagination, still to her pure spirit it seemed by far too hideous to be true, and she scarcely could be said really and truly to entertain it as a matter which was likely to be true.