The act of regicide, a violation of natural order and divine right, irrevocably shatters Macbeth's psyche. The moment after King Duncan draws his last breath, Macbeth is plunged into a state of profound horror and immediate, crushing guilt. Far from the triumphant assertion of power he might have anticipated, the deed unleashes a torrent of psychological anguish, marking the beginning of his irreversible descent into paranoia and tyranny. The blood on his hands becomes a potent symbol not just of the physical act, but of the indelible stain on his soul, a stain that will forever preclude peace.
Immediately following the murder, Shakespeare portrays Macbeth as paralyzed by his actions. He hears phantom voices, cries of "Sleep no more! Macbeth does murder sleep," which echo the loss of innocence and tranquility. This auditory hallucination is not mere fancy; it signifies the profound disruption of his inner world. Sleep, a natural restorative, is now denied to him, replaced by a restless, guilt-ridden wakefulness. The very stillness of the castle after Duncan's death, a supposed symbol of order restored, becomes oppressive to Macbeth. He is consumed by the immediate, tangible evidence of his crime: the blood. Lady Macbeth's pragmatic instruction to wash their hands appears futile to him, highlighting his overwhelming sensory and emotional response. "Will all great Neptune’s ocean wash this blood / Clean from my hand?" he laments, his words conveying the sheer impossibility of cleansing his stained conscience. This visceral reaction underscores that the psychological cost of the murder far outweighs any perceived benefit.
Macbeth's fear intensifies as he contemplates the future. The murder of Duncan is not an isolated event but the first step in a chain of violence, a fact he grasps with chilling clarity. He worries about the "clearest proofs" of his deed and the possibility of discovery, a paranoia that fuels his increasingly desperate measures. The unnatural events that follow Duncan's death – the "darkness" that "cloys the sun" and Duncan's horses eating each other – are interpreted by Macbeth as omens, reflections of the cosmic disorder his actions have wrought. He feels exposed, not just to human judgment, but to a divine retribution. This fear is not only for himself but also for the stability of his reign, which is built on a foundation of murder. The weight of his secret isolates him, even from his wife, as the initial shared burden of guilt begins to fracture their unity.
The chilling realization that his ambition has led him to a point of no return dominates his thoughts. Macbeth begins to understand that the "golden round," the crown he so craved, is now a symbol of his damnation. He has sacrificed his moral compass and his peace of mind for a prize that offers no solace. The blood that stains his hands is a constant, sickening reminder of what he has lost: his honor, his sleep, and his humanity. The anticipation of further violence, necessary to secure his ill-gotten gains, casts a long shadow over his immediate present. He knows he has "supped full with horrors" and that each new day will bring fresh anxieties and the necessity of further bloodshed. The initial exhilaration of ambition has curdled into the bitter taste of regret and dread, a dread that will only deepen as the play progresses.
In essence, Macbeth’s feelings after killing Duncan are not those of a triumphant conqueror, but of a man profoundly tormented by his conscience. The horror of the act, the loss of sleep and peace, and the gnawing fear of discovery and retribution combine to create a potent psychological crisis. He is trapped by his own deed, haunted by the blood on his hands and the knowledge that he has irrevocably altered his destiny for the worse. The murder marks not an accession to power, but a descent into a personal hell from which there appears to be no escape.