Holmes: You don't think it the least bit coincidental that both you and young Mr. Castoro decided to visit the cemetery the day after his father's birthday?
Watson: Yes. Of course I do.
Holmes: But you still want to give him the money.
Watson: It's complicated. You don't know him.
Holmes: I also know, as does he, that you blame yourself for the man's death.
Watson: Because it was my fault.
Holmes: It was an accident. And as loathe as I am to admit it, accidents happen. Joey's goodwill obviously means a great deal to you. But the fact that he has on more than one occasion attached a dollar figure reveals his character. Or at least it does to me. I'm an expert on poisons, Watson. I know virtually everything there is to know about them. But I've come to learn over the last few years that there is nothing on this planet quite so toxic as guilt.