Final answer:
Lady Macbeth's soliloquy supports the idea that she is a 'fourth witch' due to her embrace of darkness and desire for power.
Step-by-step explanation:
In Shakespeare's play Macbeth, Lady Macbeth is often compared to a 'fourth witch' due to her manipulative and cunning nature, as well as her involvement in the supernatural. The soliloquy that supports this idea is when Lady Macbeth calls upon the spirits to 'unsex' her and fill her with 'direst cruelty.' This soliloquy showcases her willingness to embrace darkness and her desire for power, which aligns with the themes of witchcraft and supernatural in the play.
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