What is the best way to find rhetorical devices in Macbeth?

Rhetorical devices are literary techniques that a writer uses to persuade his or her audience. If I were looking for rhetorical devices in Macbeth, I would focus on the scenes that show Lady Macbeth’s machinations and Macbeth’s inner turmoil over whether or not to kill Duncan. These sections are rich in rhetorical devices because they are full of dissenting opinions, as well as characters trying to persuade either themselves or others to take a particular course of action.

More specifically, I would focus on Macbeth’s monologue at the beginning of Act I, Scene 7 and Lady Macbeth’s subsequent  entreaties to him. Lady Macbeth’s lines can be found immediately after Macbeth’s Scene 7 monologue.

I urge you to focus on this small section of text because Lady Macbeth and Macbeth grapple with the ethics of killing Duncan, their king and guest.  Macbeth argues with himself and names all of the reasons why murdering Duncan would be abominable and unjust. Afterwards, Lady Macbeth strongly admonishes Macbeth for his weakness and cowardice, while Macbeth makes a futile attempt to renege on his previous plans.  

As an example, I'll describe two major rhetorical devices used by Macbeth in his monologue.  Macbeth uses simile, to describe how Duncan’s “virtues will plead like angels, trumpet-tongued against the deep damnation of his taking off"(1.7.18-20.) By comparing Duncan’s virtues to innocent angels pleading against death, Macbeth further adds to an argument built on pathos, an argumentative strategy that provokes an emotional reaction in its readers in order to persuade them.

This section also uses juxtaposition.

“Then, as his host,

Who should against his murderer shut the door,

Not bear the knife myself"(1.7. 14-16.)

As Macbeth describes his emotions in this monologue, he  juxtaposes two incredibly divergent images, shutting the door against danger and bearing the knife himself, to show that murdering Duncan would be an inhumane and unnatural act.