In "Hamlet," how does Shakespeare develop and enrich the image of madness by always changing it?
In reading your question, I thought of the real madness that eventually happens to Ophelia and the feined madness of Hamlet.
Initially what we are seeing is a pretending of madness by Hamlet. He has determined that he will act so insane that no one (especially his uncle/step-father) will suspect that he knows about his father's murder. As the story progresses, there are times when we may question whether Hamlet is still truly sane and pretending to be mad, or if he's actually gone around the bend and lost it, particularly when he's screaming at his mother in her chamber (3.4). So this image of madness is enriched by Hamlet's use of it as part of his plan to eventually kill Claudius.
Ophelia, however, is another matter. She truly does go insane after her father's death, although I suspect her madness began while she was being used as a pawn by Polonius, Claudius, and even Hamlet himself. We see her becoming weaker and weaker as the play progresses, as she's forced to give up seeing Hamlet, then as Hamlet takes out all of his frustrations on her, then as she's dangled like bait in front of Hamlet by Polonius. Her madness is real and tragic and is a foil to the feigned madness of Hamlet.
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