They are the only ordinary family we see in the play, and their murder makes Macbeth's tyranny concrete. The child is stabbed on stage (Act 4, Scene 2), the only killing of a child the audience witnesses.
- "the poor wren, / The most diminutive of birds, will fight, / Her young ones in her nest, against the owl." (Act 4, Scene 2). She accuses her absent husband of lacking "the natural touch". The tiny wren fighting a predator is her picture of what a parent should be.
- "I am in this earthly world, where to do harm / Is often laudable; to do good sometime / Accounted dangerous folly" (Act 4, Scene 2). The antithesis makes "harm" praiseworthy and "good" a "dangerous folly": under Macbeth, moral values have been turned upside down, the world of "Fair is foul" (Act 1, Scene 1) seen by a victim.
Her son's cheeky logic, that "there are liars and swearers enow to beat the honest men and hang up them", exposes a corrupt Scotland. Use Lady Macduff as a foil to Lady Macbeth: a mother, protective and powerless, against a woman who imagined killing her own baby, and who later asks in her sleep "The Thane of Fife had a wife. Where is she now?" (Act 5, Scene 1). Their deaths also raise the hardest question about Macduff's flight.