Having been stricken with immediate passion for Juliet, Romeo cannot bear to part from her when the festivities end:
Can I go forward when my heart is here?
Turn back, dull earth, and find thy centre out. (2.1.1-2)
His friends, however, do not realize that Romeo has dismissed Rosaline from his mind and filled his heart with Juliet's image as he scales the walls of the orchard to wait beneath her balcony. Instead, they search for him, thinking that he still mourns the loss of Rosaline. Therefore, it is with irony that Mercutio summons Romeo,
Romeo! Humors! Madman! Passion! Lover! (2.1.7)
With further irony, Mercutio pronounes that love is blind, so it cannot hit the mark, and he calls out his farewell to Romeo, saying that it is too cold outside for him. Benvolio concurs, declaring that it is in vain that they seek him.