How we cite our quotes: (Part.Letter.Paragraph)
Quote #1
Let her believe in virtue, but let her sacrifice it for my sake. (1.6.3)
An as object for his seduction, Madame de Tourvel appeals to Valmont precisely because she has uncompromising principles. She poses more of a challenge for him. He doesn't want her to give up her principles, but to violate them.
Quote #2
But Valmont is not a man of that sort: his conduct is the outcome of his principles. He knows exactly how far a man may carry villainy without danger to himself, and, so that he can be cruel and vicious with impunity, he chooses women for his victims. (1.9.2)
According to Madame de Volanges, Valmont is a man of principle, but his principles are evil. He's an evil man, but very calculating and deliberate. Do you agree with her assessment?
Quote #3
You renounce your bold schemes that have succeeded before, so that you now lead a life devoid of principles, leaving everything to chance, or rather the whim of the moment. (1.10.1)
Madame de Merteuil, contrary to Madame de Volanges, believes that Valmont's endeavors where Tourvel is concerned will be a move away from Valmont's characteristic principles of controlled and premeditated evil. Merteuil sees this as a very dangerous way to live; it leaves you open to having your emotions overwhelm your better judgment. And by better judgment, we mean purposefully evil intent.