Determinism vs. Free Will, the quintessential philosophical debate that is present in everything from the Bible to the Matrix, makes a surprise appearance in Macbeth. This inclusion is a facet of the play whose prevalence I did not notice until I memorized my assigned Macbeth lines.
Macbeth's character arc, his rise to power and inevitable demise, revolves around the prophecies told to him by the three witches, but before learning my lines I had not grasped the degree to which deterministic views figured into the play.
After learning of his newfound title, Macbeth mumbles to himself "I am Thane of Cawdor, if chance will have me king, why chance may crown me, without my stir." Macbeth seems comfortable with the idea of Fate deciding his ascendence, and seems resigned to whatever his destiny may be. While I made a note of this line upon my first read-through of Macbeth, it was not until I memorized Macbeth's dialogue with Ross and Banquo that I noticed the how often the theme of Fate is utilized concerning Macbeth.
As Macbeth continues his dialogue, he remarks to Ross and Banquo "Think upon what hath chanced." He seems obsessed with the idea that events are externally determined, and this deterministic viewpoint is eventually his downfall.
Upon learning that Macduff was prematurely taken from his mother's womb, Macbeth loses all of the confidence and swagger that had allowed him to absolutely dismantle any previous challenger. Because of the witches' prophecy about a "man of woman born", Macbeth believes that he has met his maker as soon as Macduff is shown to fulfill the qualifications.
In conclusion, as a consequence of memorizing my thirty lines, a task I initially thought unfeasible, I gained an awareness about how Macbeth's deterministic ideology leads to his eventual death.