In Act 1 Scene 5, Lady Macbeth receives a letter from her husband. Macbeth tells her of King Duncan’s plan to spend that night in the Macbeths' home at Inverness Castle. He also tells her of the noble and royal predictions that the three witches make of his future. This follows the famous soliloquy of Lady Macbeth. This itself explains the entire theme of the play. The evil influence already casted on Macbeth by the witches continues to be working in the form of Lady Macbeth. In this scene some critiques have considered her as the fourth witch. When we take this this is in co relation with the theme of the play that is deception and evil influence.
The character of Lady Macbeth and Macbeth and Duncan also is described nicely in this soliloquy. The chant “foul is fair and the fair is foul” is very well described in this scene. Duncan the good king is about to be killed and the wicked Macbeth and Lady Macbeth is about to be the King and the Queen.
The dramatic purpose of this scene is to make the the entire play correlative. The prophesy of the witches have already created a seed of ambition in the mind of Macbeth and this soliloquy helps the reader to understand that this seed will be sprouted very soon. That means the murder of Duncan will be very soon.