What are the appearance vs. reality motifs in Act IV of Macbeth?
The appearance vs. reality motif appears in the extended conversation between Malcolm and Macduff which begins at the beginning of Scene iii. Malcolm, deep in the political chaos that has resulted from Macbeth's murder of his father, King Duncan, is wary, well aware of the danger around him. He questions Macduff's intentions, fearing that Macduff supports Macbeth. To test Macduff's love for Scotland, Malcolm engages Macduff as Malcolm creates a false reality in regard to his own character [ll. 50-102]. Malcolm paints himself as the worst of all possible rulers; Macbeth, he says, will appear "as pure as snow" in comparison to himself [ll. 50-54]. Macduff accepts Malcolm as what he appears to be, saying that he is not only unfit to govern, he is not fit to live.
Once he is sure of Macduff's loyalty to Scotland, Malcolm then destroys the appearance of his own vile nature that he has so carefully constructed and tells Macduff the truth about his real nature [ll. 114-137]. Thus appearance vs. reality is found in Malcolm's two descriptions of himself.
Also, the apparitions summoned by the witches in Scene i create appearance vs. reality. Their predictions make it seem that Macbeth is invincible [ll. 80-81 and ll. 92-94]. Their words are deliberately deceptive; in reality, he is not invincible, even though each prediction comes true in a manner Macbeth could not anticipate. Birnam Wood does move to Macbeth's castle, and Macbeth is slain by a man who was not "born" by a woman.