The relationship between Ariel's invisibility and his music serves to advance the plot by
O making Caliban and Stephano feel unsure of what is real, then causing
them to look for the source
O convincing Caliban the island is haunted, and making him change his
plans to destroy Prospero
causing others to punish Trinculo for lying, and giving Stephano
confidence
O
scaring Stephano at first, then motivating Trinculo to want to rule the
island