If I took him alive, Mademoiselle Stangerson and Robert Darzac would, perhaps, never forgive me! And I wish to retain their good-will and respect.
"Seeing, as I have just now seen, Mademoiselle Stangerson pour a narcotic into her father's glass, so that he might not be awake to interrupt the conversation she is going to have with her murderer, you can imagine she would not be grateful to me if I brought the man of The Yellow Room and the inexplicable gallery, bound and gagged, to her father.

I realise now that if I am to save the unhappy lady, I must silence the man and not capture him.

To kill a human being is no small thing.

Besides, that's not my business, unless the man himself makes it my business.

On the other hand, to render him forever silent without the lady's assent and confidence is to act on one's own initiative and assumes a knowledge of everything with nothing for a basis.