| Quote #1
"Why, yes; and not exactly that either. The fact is, we have all been a good deal puzzled because the affair is so simple, and yet baffles us altogether." (9)
Well, how's that for cunning? G— has already worked with Dupin on two cases, so he know perfectly well that Dupin won't be able to resist showing off and solving the case.
| Quote #2
"Perhaps the mystery is a little too plain," said Dupin. (12)
Seriously? It seems to us that the mystery isn't actually plain at all. A card-holder dangling from a fireplace isn't actually an obvious hiding place—not to mention that the letter has been disguised. Dupin only finds it because he knows it's in a place that G— and his force didn't look.
| Quote #3
"Its rightful owner saw, but of course dared not call attention to the act in the presence of the third personage, who stood at her elbow." (28)
Tricky D— cunningly anticipates that the royal lady won't call him out in front of the royal man and risk having her secret betrayed. So far, it's a win for D—.