If he were to rule Scotland, then he better rule it under total control.
Aside from Macbeth's logical principles, he had three fundamental reasons why he should not murder Duncan. If he were to kill Duncan he would be committing a triple murder and the heavens would turn against him: .
"First, as I am his kinsman, and his subject,.
Strong both against, the deed; then, as his host,.
Who should against his murderer shut the door, .
Not bear the knife myself. Besides, the Duncan.
Hath borne his faculties so meek, hath been.
So clear in his great office-(Shakespeare, I, vii, 13-18).
Macbeth was clearly a man of great honour. He had loyalty to his King, love for his family, and a good sense of morality. All these reasons in Macbeth's mind proved him to be fully conscience and righteous. He was not a mad man and therefore, using common sense, he would not have killed Duncan. Unfortunately, Lady Macbeth was there to convince him otherwise. .
The evening Duncan was staying at Inverness, Macbeth left supper early for a reason unknown to others. Him and Lady Macbeth both agreed on the plan to murder the King that evening. Lady Macbeth was evidently worried about Macbeth when he left the dinning chamber. After she found him, her short breathed questions showed signs of fright and tension as if something might have went wrong with their agreement. Her outlook was in fact true. The reason behind the early departure was because Macbeth's conscience mind had been trying to persuade him not to kill his King. He had spent some time deciding if he should continue with the plan or abandon it. In Macbeth's debate over the pros and cons of killing Duncan, the conclusion he came to was not to kill him. Immediately, Macbeth informed his wife that they will "proceed no further in this business." (Shakespeare, I, vii, 31) Macbeth's determined tone to cancel their plan was established so effectively that without Lady Macbeth's following accusations, Macbeth would have remained with the decision to not kill Duncan.
