SARAH: Again, Gertrude's words here suggest that she doesn't understand what Hamlet's accusing her of - of course, it's also possible that she simply wants Hamlet to believe this to be true.

RALPH: Hamlet replies by accusing her of an act that blurs, or tarnishes, the grace and blush of modesty. This is of course the fact that she's remarried her brother-in-law. He seems to have left out his earlier additional accusation, that she was also complicit in killing King Hamlet.

SARAH: Hamlet stacks up metaphors to support his attack: he describes the innocent and virtuous love of Gertrude and King Hamlet's as having a rose on its forehead - and remarrying Claudius has replaced this rose with a blister.

RALPH: In Shakespeare's day prostitutes were sometimes punished by getting branded on their foreheads, while a white rose was worn on clothing as a symbol of virtue and chastity. So, the image of the rose has been replaced by a blister from a branding iron, just as virtue has been replaced by vice.

SARAH: And finally, marriage vows have been made as false as dicer's oaths - as untrustworthy as the promises made by gamblers. In other words, Gertrude's original marriage vows - presumably that she would stay true to King Hamlet forever - have been proven false by her new marriage vows, and this has made them meaningless.