Immediately after hearing the witches' prophecy that he will be Thane of Cawdor and later King of Scotland, Macbeth is taken aback. We know this because Banquo asks why he seems to fear "things that...sound so fair." When Ross and Angus inform Macbeth that he has become Thane of Cawdor (the current Thane of Cawdor will be executed for treason) we learn that his ambitions have been kindled. He says, as an aside, that the "greatest [obstacle] is behind." In fact, Macbeth goes on to describe his state of mind upon learning this news in a short soliloquy. He says that he is struggling to figure out if the witches' prophecy is "ill" or "good." He is struck by the perception that part of the prophecy has come true, but is somewhat fearful of the feelings it has aroused in him. His heart, he says, is beginning to "knock against [his] ribs" and he acknowledges that his "present fears" are "less than horrible imaginings." He concludes by saying that "if chance will have me king...why chance may crown me without my stir." So he is fearful and exhilarated, but he has also had his ambitions piqued in a way that will turn out to be disastrous. All of these emotions are swirling around in his mind after meeting the witches and especially after finding out that he has become Thane of Cawdor.