Final answer:
In Shakespeare's 'Macbeth,' Lady Macbeth expresses the desire to turn nurturing milk into bitter gall, symbolizing her ambition and loss of humanity.
Step-by-step explanation:
The desire to replace nurturing with bitterness, specifically referring to milk turning into gall, is expressed by Lady Macbeth in Shakespeare's "Macbeth." This metaphorical speech by Lady Macbeth demonstrates her ruthless ambition and willingness to forsake her femininity and maternal instincts for power. The contrast between the nurturing milk and the bitter gall underscores the transform in her character from compassion to savagery as she encourages Macbeth to commit regicide.