Had Macbeth already thought of killing Duncan?

Answer 1

Yes, Macbeth [c. 1014-August 15, 1057] early on considered killing King Duncan I [d. August 14, 1040]. In Act 1 Scene 3 of the Shakespearean play, Macbeth heard the witches' predictions of noble and royal promotions for him. Then he heard the news from the noble Scotsmen Angus and Ross of his receipt of the powerful title and profitable possessions of the Thane of Cawdor. Macbeth had to have known that King Duncan I [d. August 14, 1040] would have planned to be succeeded by his own children, the future Kings Malcolm III [d. November 13, 1093] and Donald III [d. 1099]. So he had to have known that something untoward would have to happen for him to become King. In fact, in lines 134-142, he pondered means 'against the use of nature'. Such means to an end could have included king-killing. Then in Scene 4, he witnessed the King giving the title of Prince of Cumberland to Malcolm, the elder of the two children. That title identifed Malcolm as the heir apparent to the throne. Macbeth again considered foul means to realizing his royal destiny. In lines 48-53, he recognized the title as an obstacle that had to halt his progress or be dealt with. Most definitely did he consider foul means, which he called 'black and deep desires'.