When the Duchess is happy about something – and we really mean anything, her marriage, her dinner, the weather, anything at all – she smiles and blushes, and the Duke describes her blush s a "spot of joy" (21) that appears in her cheek. The spot of joy is an involuntary signal of the Duchess's pleasure, something that she can’t control, that betrays her inner feelings to the world. The Duke thinks of it as a "spot" – a stain, a symbol of her tainted nature.
- Lines 13-15: The Duke uses a tongue-in-cheek understatement to emphasize how many things cause the "spot of joy" to appear in the Duchess's cheek.
- The phrase "spot of joy" itself is a startling juxtaposition of images that makes the reader think differently about the kind of blush that crosses the face of the Duchess. The fact that her blushing is referred to as a "spot" makes it sound blameworthy.
- Lines 21-22: In order to convey that he perceives the Duchess as flirtatious, the Duke comes up with a euphemism – "too soon made glad," which is a roundabout way of saying "easily pleased" – or maybe just "easy."
- Of course, that may not be an accurate characterization of the Duchess – but that’s how the Duke perceives her. Since the Duchess isn’t here to defend herself, all we have to go on is the Duke’s claim.