In the first act of Macbeth, Macbeth makes an aside immediately following King Duncan's proclamation that Malcolm is the next in line for the throne. In the previous scene, Macbeth learned from the witches that he would become the Thane of Cawdor and then the King of Scotland. At the end of the scene, Rosse delivers the news to Macbeth that he has in fact been named the Thane of Cawdor. This news causes Macbeth to trust the verity of the witches' prediction, so he has set his desire and ambition on becoming the next King of Scotland. When Malcolm is named the next King, Macbeth thinks that this is a terrible obstacle that is preventing him from achieving his goal. Macbeth thinks that he is full of "black desires" because he is starting to think that he will need to engage in ill acts to become King. Malcolm is in the way, and Macbeth must devise a plan to clear the way for himself.