Final answer:
The subject of the quote from Macbeth is guilt, as it examines the psychological impact of the characters' actions and their varying responses to the murder of King Duncan.
Step-by-step explanation:
The lines from William Shakespeare's Macbeth, "Will all great Neptune's ocean wash this blood Clean from my hand? No, this my hand will rather the multitudinous seas incarnadine, Making the green one red" and Lady Macbeth's contrasting notion that "A little water will clear us of this deed," highlight the overarching theme of guilt experienced by both characters after murdering King Duncan. While Macbeth is overwhelmed by the enormity of their crime, fearing that not even the vast oceans can cleanse him of his guilt, Lady Macbeth appears more pragmatic and untroubled, suggesting that a simple act of washing will remove the physical evidence and, by implication, any residual guilt. These differing responses to the same deed underscore the psychological burden that guilt can impose on individuals, with Macbeth's vivid imagery reflecting the indelible stain that their actions have left on their consciences.