In Macbeth, Shakespeare compares different characters and their approaches to their reigns, some successful and others not, possibly demonstrating which qualities he felt were most important in a good monarch
Macbeth: '“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”'
Macbeth's transformation is so complete by the time he kills Duncan that it is too late for him to go back to being the noble Macbeth introduced at the start of the play
Macbeth: '“They hailed him father to a line of kings. Upon my head they placed a fruitless crown and put a barren sceptre in my gripe, thence to be wrenched with an unlineal hand, No son of mine succeeding”'