In his soliloquy, Macbeth gets cold feet about killing Duncan
Act 1, Scene 1 of Shakespeare’s Macbeth is set at night in the Macbeths’ castle where King Duncan is currently staying. In the first part of the scene, Macbeth delivers a soliloquy in which he weighs the pros and cons of going through with the murder of Duncan.
In reality, Macbeth is mainly listing the arguments against the murder. First, he is aware that if he becomes king through the murder of the current king, he risks teaching others that they could kill him in turn. Thus, his evil plan might “return / To plague the inventor” (1.7.9-10).
Second, Macbeth has moral scruples because Duncan is both his king, his relative, and his guest (1.7.12-16). By killing Duncan in his sleep, Macbeth would be breaking the trust between them and neglecting his duty as a loyal subject, relative, and host. Particularly Duncan’s position as king makes the crime virtually impossible: Killing a king - regicide - was considered the worst possible sin.
Third, Duncan has been a good king who is loved by everyone, which makes it even harder to kill him: “Duncan / Hath borne his faculties so meek […] that his virtues / Will plead like angels, trumpet-tongued, against / The deep damnation of his taking-off.” (1.7.16-20). Macbeth also concedes that “He hath honour’d me of late” (1.7.34), referring to the title of thane of Cawdor which Duncan has recently rewarded him with.
In the end, Macbeth gets cold feet. Murdering his king just does not feel right. As Lady Macbeth enters, he tells her that “We will proceed no further in this business”...