‘Stars, hide your fires!’
This is a quote from Macbeth to the audience, expressing his thoughts. ‘Stars, hide your fires!’ The ‘Stars’ are the people and God in the heavens, and to hide their fires means to not watch Macbeth. He wants to hide his desire to be king, and his treasonous thoughts. He wants to keep his desires hidden, as his desire is now to do anything to be king.
In scene 4 we learn that the traitorous Thane Of Cawdor has been executed, and the Thane faced his execution with honour and dignity. The king praises Macbeth and Banquo and then names his son Malcolm as his heir and future king of Scotland. Macbeth is unsettled by this sudden announcement and has a change of mindset, he now has a strong desire to be king.