Critics disagree with the purpose of the porter of Act II, Scene 3 in Macbeth: Some feel that he provides comic relief as well as suggesting insights into the them and the character of Macbeth, while others perceive this scene as that of hell and the porter is the devil:
Knock, knock, knock! Who's there, i' th' name of Beelzebub?
The porter admits the farmer, the English tailor, and the equivocator. The farmer represents Macbeth because like him, Macbeth causes his own death in his "expectation of plenty," or his "vaulting ambition" as he calls it desire to be king of Scotland. He is like the tailor in his acts of "stealing out of a French hose," his causing of Lady Macbeth's insanity and death while they both attempt to build his power as King of Scotland.
And, he is like the equivocator because he, too, can "swear in both the scales against either scale" and has acted treasonly by killing King Duncan,
committed treason enough for God's sake, yet could not equivocate to heaven. 2.3.
The allusion here is to Father Henry Garnet, a Jesuit priest, thought to be a conspirator himself who revealed a couple of plotters involved in the Gunpowder Plot to mitigate his guilt, and was known as the "great equivocator." He was himself hanged. Some authorities also believe that Father Garnet tried to avert a plan to kill King Jame I. Macbeth is similar to Garnet in that he attempts to implicate Duncan's guards as the murderers in order to cast the guilt upon them rather than upon himself.