Unlike the fast-paced dialogue of recitative, an aria leaves a character exposed.
Characters like Handel's Cleopatra represent "Amor" as a tool for power, yet they eventually succumb to its "unexpected vulnerability".
An aria is literally "air." It is the moment in an opera where the plot freezes, and time expands to accommodate a single character's internal reality. When that reality is "Amor," the music becomes a physical manifestation of longing.