Final answer:
The apostrophe in Shakespeare's Macbeth occurs when Macbeth speaks to the earth, asking it not to reveal his steps. This is a classic use of apostrophe where an inanimate object is addressed as if it could respond.
Step-by-step explanation:
The part of the excerpt from William Shakespeare's Macbeth that uses apostrophe is:
Thou sure and firm-set earth,
Hear not my steps, which way they walk, for fear
Thy very stones prate of my whereabout,
In this passage, Macbeth speaks to the earth as if it were a listening being capable of betraying his footsteps. This figure of speech, where a speaker directly addresses someone absent, an abstract concept, or a non-human entity, is known as an apostrophe. Shakespeare uses it here to convey Macbeth's heightened state of anxiety and desire for his murderous actions to remain undiscovered.