Explain the contrast between Duncan's statements to Lady Macbeth and her plans for him.

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teachersage eNotes educator| Certified Educator

Duncan arrives at Macbeth's castle in Act I, scene vi thanking Lady Macbeth for taking the trouble to host him. He speaks of Macbeth and Lady Macbeth as hospitable, which would include providing protection to him as their guest. He mentions Macbeth's great love for him:

And his great love, sharp as his spur, hath holp him
To his home before us. Fair and noble hostess,
We are your guest tonight.
Duncan refers to Lady Macbeth as "noble" and says that because of his great love for Duncan, Macbeth has ridden home ahead to help prepare to greet him as a guest. 
In fact, Lady Macbeth plans to have her husband murder Duncan. Rather than offer hospitality and protection, she plans to kill this guest so that her husband can become king. This is an example of dramatic irony, which is when the audience knows something a character doesn't. In this case, the audience already knows from the previous scene that Lady Macbeth's plans for her king are anything but loving and hospitable. We know that Duncan is walking into a trap.