Anaphora is a rhetorical device that involves the repetition of words or phrases at the beginning of sentences or clauses. Anaphora is used to stress or emphasize an idea.
Shakespeare uses anaphora in Macbethduring the conversation between Malcolm and Macduff in Act IV, scene iii. Macduff is pleading with Malcolm to return to Scotland to overthrow Macbeth and claim the throne. Macduff tries to explain the extent of the suffering the people of Scotland are enduring. He is hoping to elicit some sympathy from Malcolm. Notice the repition used when Macduff states, "...each new morn new widows howl, new orphans cry, new sorrows strike heaven on the face." By repeating the word "new," Macduff is emphasizing that each new days brings about new suffering to make Malcolm see that the abuse from Macbeth is ongoing and must be stopped.
Malcolm, trying to discern if Macduff is sincere, likewise uses anaphora when explaining why he is no better a candidate for king than is Macbeth. When he tells Macduff later in the scene that "your wives, your daughters, your matrons and your maids" will not be safe from his lust, he is trying to get an emotional response from Macduff to see if he can trust him.