47+ Macbeth Self Doubt Quotes. Macbeth is recounting what he believes is the invincibility that the witches revealed to him . This quote supports the theme of . Shall never sag with doubt nor shake with fear. Before macbeth kills duncan, he begins to have doubts about his action. Macbeth guilt quotes & analysis · act 2, scene 2: What are some examples of ambition quotes in macbeth? This quote demonstrates that macbeth is beginning to doubt his ambitious plans to . William shakespeare · doubt, doubt and fear. To saucy doubts and fears. This proves that macbeth was not fully convinced into killing duncan, and that he only did it to hide his doubts to avoid appearing a coward in front of his .