In this scene, Romeo begins a separation from his friends that continues throughout the play. His inability to reveal his love of a Capulet heightens his isolation. By leaping the wall surrounding the Capulet orchard, Romeo physically separates himself from Mercutio and Benvolio — a separation that reflects the distance he feels from society, his friends, and his family.
Romeo previously wallowed in a "prison, kept without food" (I.2.55) as his unrequited love for Rosaline withered from lack of reciprocation. Having joked at Romeo's Petrarchan miseries earlier in the play, Mercutio now adds a more cutting edge to his barbs. He calls to Romeo using physical and sexual innuendo to describe the female allure. To Mercutio, love is a conquest, a physical endeavor. Mercutio jests that Romeo will think of Rosaline as a medlar fruit, which was supposed to look like the female genitalia, and himself as a poperin pear shaped like the male genitalia.
Romeo's leap over the Capulet wall is symbolic of his flight to a spiritual conceptualization of love. He has moved beyond Mercutio's crude understanding of love — "quivering thigh, / And the demesnes that there adjacent lie" — to a less physical, more mystical perception of love.
Romeo describes Juliet in light images — conspicuously nonphysical descriptions. When he first sees Juliet, he says, "she doth teach the torches to burn bright." Romeo has often sought sanctuary in the dark, but the deepest shade has never satisfied him. Recall that he locked himself away in his room and shut the windows to create an "artificial night" while pining for Rosaline in Act I, Scene 1. Juliet transports him from the dark into the light, moving Romeo to a higher spiritual plane. Ironically, however, Romeo and Juliet's clandestine love can only flourish under the shelter of night.
