How we cite our quotes: Volume.Part.Chapter.Paragraph
Quote #4
"I do understand it, Laura. He is mad—mad with the terrors of a guilty conscience." (2.1.7.114)
Sir Percival is basically a portrait of the psychology of guilt and the effect it can have on someone's behavior. Don't tell the truth because it's morally correct—tell the truth so you don't have to suffer guilty-conscience-based madness!
Quote #5
My distrust of his unfathomable falseness, my sense of my own degradation in stooping to conciliate his wife, and himself, so disturbed and confused me, that the next words failed on my lips and I stood there in silence. (2.1.8.16)
This powerful passage gives us great insight into Marian's turbulent emotions. The diction here really makes Marian's disgust and hatred of Fosco palpable. Another reason to not lie: Marian (the world's coolest woman) hates liars.
Quote #6
You have taken your own mean, underhand view of the innocent deception practiced on Lady Glyde, for her own good. (2.3.2.147)
Sir Percival's lame defense of the "deception" he uses to get Laura out of the house emphasizes what a creep he is. But what's interesting is that Walter and Marian later practice an "innocent deception" of their own against the ever-helpless Laura. We could kick-start a really interesting debate about intentions and the morality of lying here.