In act 2 scene 1, Macbeth’s great soliloquy ends the scene with him resolving to kill Duncan, the king. Think about how momentous this decision is. In the Middle Ages and for centuries after, kings ruled by Divine Right, the people believing that kings were appointed by God. Killing a king amounted to defying God, so the stakes are greater here than most today can imagine.
Take a look at the ending lines of the soliloquy, beginning with “Thou sure and firm-set earth,” about line 56 in most versions, and read to line 64. Think about what Macbeth is saying and how he is saying it. This is a crucial part of the play because how it is presented will indicate how convinced Macbeth is that he is indeed doing the right thing.