In his first appearance, King Duncan performed two of the basic duties of a king: punishing evil and rewarding good. Upon learning of the treachery of Cawdor and the heroism of Macbeth, he announced, "No more that thane of Cawdor shall deceive / Our bosom interest: go pronounce his present death, / And with his former title greet Macbeth" (1.2.63-65). The phrase "bosom interest" means "vital interests," but "bosom" suggests that a relationship of love should exist between a king and his subject.
After the witches proclaimed Macbeth as "Thane of Glamis," "Thane of Cawdor," "and king hereafter!" (1.3.50), he received the news that he had been named Thane of Cawdor. This news threw him into a daze, in which he said to himself, "Two truths are told, / As happy prologues to the swelling act / Of the imperial theme" (1.3.127-129). Macbeth's metaphor was dramatic; he seemed to be imagining himself as making an ostentatious entrance as king.
When Lady Macbeth received her husband's letter about the witches' prophecies, she was only worried that her husband is "too full o' the milk of human kindness / To catch the nearest way" (1.5.17-18). However, she obviously had no such problem, so she was eager for the chance to make him see things her way. "Hie thee hither, / That I may pour my spirits in thine ear; / And chastise with the valour of my tongue / All that impedes thee from the golden round," (1.5.25-28). She planned to appeal to his ambition and excise everything in him that prevented him from being merciless enough to seize the crown.
While King Duncan was at dinner Macbeth almost talked himself out of the murder. He figured that King Duncan was a good king, not arrogant or selfish. Macbeth said to himself that the king "Hath borne his faculties so meek, hath been / So clear in his great office, that his virtues / Will plead like angels, trumpet-tongued, against / The deep damnation of his taking-off" (1.7.17-20). Duncan's reign was marked by the king's kindness, generosity, and stabilizing presence. Therefore, two of the most vital duties of a king were to keep order and to reward his subjects according to their merits.
King Duncan should have been honored and respected for his deeds, rather than brutally murdered. Therefore, his murder was unnatural. A few days after Duncan's assassination, Ross (another of Duncan's thanes) and an Old Man told each other of all the unnatural things that had been happening in the kingdom. They did not know that Macbeth was the murderer, but the unnatural events clearly parallel the contrast between King Duncan and Macbeth. For example, Duncan's horses, "Beauteous and swift, the minions of their race, / Turn'd wild in nature, broke their stalls, flung out, / Contending 'gainst obedience, as they would make / War with mankind." (2.4.15-18). Macbeth and Lady Macbeth were King Duncan's minions. The King showered them with honors and gifts, but they turned wild and made war on their master.
The difference between the two types of rulers may be best expressed in a conversation that occurs in Act IV, scene iii, when Macduff met Malcolm in England. Planning to overthrow Macbeth's tyrannical rule, Malcolm pretended that he would make an even worse king than Macbeth. He did so in order to test Macduff's loyalty to Scotland. He told Macduff of his own less-than- desirable qualities-among them a hunger for power and a pugnacious disposition, both of which seem to perfectly describe Macbeth himself. On the other hand, Malcolm said "The king-becoming graces [are] justice, verity, temp'rance, stableness, / Bounty, perseverance, mercy, [and] lowliness-" ( .92-93).
According to Malcolm, the model king offered the kingdom an embodiment of order and justice. Macbeth only wished to be king to gratify his own desires, but Duncan and Malcolm wore the crown out of love for their nation. In the play, Duncan was always spoken of as "the king," while Macbeth is simply known "the tyrant". Macbeth brought only chaos to Scotland-symbolized in the awful weather (he seemed to be a veritable lightning rod for thunderstorms) and bizarre supernatural events, such as the Old Man spoke of in Act II, "A falcon, towering in her pride of place/Was by a mousing owl hawk'd at and killed". Macbeth offered no real justice-only a habit of murdering those he saw as a threat, such as Banquo(who used to be his friend and ally), Banquo's son Fleance, and Macduff's wife and children. As the incarnation of tyranny, Malcolm had to overcome Macbeth so that Scotland could have a true king once more.