Captain Beatty references The Tempest by William Shakespeare at a time when he is manipulating Montag, eventually leading him to implicate himself in the crime of reading a book. A major theme in The Tempest is the difficulty of distinguishing men from monsters. This theme is explored in Shakespeare's play in the relationship between Prospero and Caliban. Each character claims to have treated the other justly, but ultimately it is left to the audience to decide which character they believe.
Similarly, Montag is listening to two very different opinions on the reason books have been banned in his society. Two important quotes from the book illustrate both sides of this argument:
"A book is a loaded gun in the house next door. Burn it. Take the shot from the weapon. Breach man’s mind." Captain Beatty, "The Hearth and the Salamander"
"Do you know why books such as this are so important? Because they have quality. And what does the word quality mean? To me it means texture. This book has pores." Faber, "The Sieve and the Sand"
The former quotation comes from Beatty's first confrontation with Montag about his possession of the books, when Beatty simultaneously encourages Montag to read the books and explains why books have no place in society. The latter quotation comes at a time when Montag is unsure of his captain's position. However, Montag attempts to do the right thing and return the books as demanded by his superior, only to have that same man (Beatty) demand he burn his own house down after Mildred turns him in.
Montag chooses to trust Captain Beatty over Faber, believing that he can trust him, only to have his trust betrayed. Montag is unsure of Faber's position on literature because it goes against what he has been taught to believe, which leads him to place his trust in the institution he is most familiar with. However, it turns out that Captain Beatty and the other firemen are not trustworthy—rather, they are the monsters he should have feared.