Macbeth’s guilt about murdering his king, Duncan, and ordering the murder of his friend, Banquo, causes him to have guilty hallucinations. Lady Macbeth also hallucinates and eventually goes insane from guilt over her role in Duncan’s death. The fact that both characters suffer torment as a result of their actions suggests neither Macbeth nor his wife is entirely cold-blooded. Although they commit terrible crimes, they know, on some level, that what they’ve done is wrong. Their guilt prevents them from fully enjoying the power they craved. Lady Macbeth says “What’s done/ cannot be undone” in Act Five scene one, but her guilt continues to torment her. While Macbeth’s guilt causes him to commit further murders in an attempt to cover up his initial crimes, Lady Macbeth’s guilt drives her to insanity, and, finally, suicide.
The loss of children is a complex and intriguing theme in the play. For both Macbeth and Banquo, children represent the idea of the continuation of a family line. Macbeth has Banquo murdered in hopes of thwarting the Witches’ prophecy that Banquo will sire a long line of kings. However, Fleance is able to escape being killed, leaving open the possibility he will one day take over the throne. Macbeth and his wife have no heirs, although Lady Macbeth references having been a mother once, saying, “I have given suck, and know / How tender ‘tis to love the babe that milks me. “ This line suggests the Macbeths may have lost a child. Similarly, Macduff mourns the children Macbeth ordered killed and uses their memory to spur him on to victory against their killer; and Siward laments the loss of his son in the play’s closing battle, but is proud to have fathered such a brave soldier who fought in a noble cause.