The subtitle of The Barber of Seville is "The Useless Precaution." This theme in drama focuses on an older man trying to restrict his young wife or fiancée, a concept that dates back to Roman theater. By the 1770s, this idea had become common in French literature, appearing in many plays and stories. While Beaumarchais adopted this theme, his interpretation was entirely original. As Frédéric Grendel observed in Beaumarchais: The Man Who Was Figaro, "The thing that matters is that Beaumarchais made the theme his own. No one before him, not even Molière, had used the devices of ellipsis and punning so freely and so naturally." John Dunkley concurred, noting in the Reference Guide to World Literature, "Beaumarchais infuses it [the theme] with new life through memorable characters and a brilliantly honed dialogue."

Beaumarchais emphasizes this theme when the audience first encounters Rosine in Act I. She pretends to drop a lyric sheet from a new comedy titled The Useless Precaution. Her interest in the play signifies her aversion to marrying the old-fashioned Bartholo, who dismisses the play as "modern rubbish" from a "barbarous century." He criticizes the accomplishments of the current era, condemning it as filled with "Every kind of stupidity: freedom of thought, the law of gravity, electricity, religious tolerance, inoculation, quinine, the encyclopedia." Beaumarchais thus shows that Bartholo is too outdated to be a suitable partner for Rosine.

Verses from The Useless Precaution recur throughout the play. In Act III, Rosine sings about the arrival of spring and the freshness of young love. Her interpretation of the song is even more revealing. She compares the end of winter—which, like Bartholo, has kept people confined indoors—to a "slave who has been locked up for a long time and then appreciates his liberty more than ever." The play concludes by reinforcing the theme. Figaro reminds Bartholo—and the audience—that "when love and youth unite to deceive an old man, anything he does to try and stop them can only be called a useless precaution."

Figaro's plan to stop Bartholo from marrying Rosine and instead bring her together with the Count relies heavily on a series of disguises. To get close to Rosine, the Count takes on different personas and wears various costumes. Figaro first spots the Count loitering outside Rosine’s window, cloaked in a priest's long brown robe and wearing a wide-brimmed hat. Even though he is dressed as a priest, the Count cannot completely conceal the characteristics that betray his true identity. Figaro notes, "No, he isn’t a reverend. That haughtiness, that nobility... I wasn’t wrong: it’s Count Almaviva."

The Count makes his initial entrance into Bartholo's household by pretending to be a drunken soldier who demands lodging for the night. This disguise allows him to express his love and deliver crucial messages to Rosine. Later, he infiltrates Bartholo's home again, this time posing as a music teacher. Bartholo, sensing the poor disguise, comments, "You look more like a disguised lover than an official friend." Despite his suspicions, Bartholo fails to uncover the truth.

The Count has additional reasons for using disguises. He opts to keep his true identity hidden from Rosine, presenting himself as a poor young man named Lindor. He tells Figaro, "Since she's already interested in me without knowing who I am, I'll keep this name Lindor; it'll be better to hide my title until I've won her." The Count wants to be certain that Rosine loves him for his true self, not for his wealth or social standing.

Music plays a crucial role...