Lady Macbeth uses metaphors to state how Macbeth is too mentally weak to be king. When Lady Macbeth finishes reading the letter on how the witches foretold that Macbeth shall be king she said “Yet I fear thy nature; It is too full o’ th’ milk of human kindness to catch the nearest way” Lady Macbeth here is saying that she thinks Macbeth is too kind to hold such power.