On the eve of Duncan's murder, Macbeth finds himself a nervous wreck, going over all the legitimate reasons not to kill Duncan before he actually goes through with the assassination. The following quote is taken from lines 7-28 during Act 1 scene 7.
             "But in these cases we still have judgment here, that we teach bloody instructions, which, being taught, return to plague the inventor. This even-handed justice commends th' ingredience of our poisoned chalice to our own lips. He's here in double trust: first as I am his kinsman and his subject strong against the deed; then, as his host, who should against his murderers shut the door, not bear the knife myself. Besides, this Duncan hath borne his faculties so meek, hath been so clear in his great office, that his virtues will plead like angels, trumpet tongued, against the deep damnation of his taking-off; and pity, like a newborn babe striding the blast, or heaven's cherubin horsed upon the sightless couriers of the air, shall blow the horrid deed in every eye, that tears shall drown the wind."
             Before Macbeth can pull out of the plan to kill Duncan, Lady Macbeth enters the scene and greed fills his heart once again. The fancies of the throne blind Macbeth's eyes to reason and rationale. If he were not, he may have thought better of the bloody plot and waited for the prophecy to come true its own. Earlier, in Act 1 scene 4, Macbeth does actually contemplate this idea.
             "If chance will have me king, why chance may crown me without my stir."
             Instead of taking this les e faire course of action, he is convinced by Lady Macbeth to take the initiative and murder Duncan.
             Another strong example of reason versus reality is displayed much later in the novel, when Macbeth has revisited the three witches in search of fate's protection. When an apparition tells him that his reign will last until the trees of Brinam wood come a...