In Act 5, Scene 3, Macbeth is growing increasingly desperate as reports are brought to him about the approaching English and Scottish forces. But he still relies on the witches' assurance that he is invulnerable until Birnam Wood comes to Dunsinane and that no man of woman born can vanquish him. This scene enables the playwright to establish that Macbeth is being deserted by all the other thanes.
Macbeth calls for his armor and begins to put it on, although he is told it is not needed yet. This was probably Shakespeare's way of saving time. If Macbeth can put the armor on now, a fairly complicated process, then there will be no need to delay the play while he gets into it offstage. Macbeth is not a thinker but a man of action. He is always relying on outside advice and is only comfortable when he is fighting and killing. It is significant that he mocks the Doctor, who is a thinker and a man of learning.
He mocks the Doctor who tells him about his wife's condition. He knows better than the Doctor what is wrong with her, because he has the same symptoms himself. He is eaten up with guilt and remorse, haunted by visions of the bloody murder of Duncan which they committed together.
This scene contains one of Shakespeare's most beautiful speeches:
Canst thou not minister to a mind diseased,
Pluck from the memory a rooted sorrow,
Raze out the written troubles of the brain,
And with some sweet oblivious antidote
Cleanse the stuffed bosom of that perilous stuff
Which weighs upon the heart?