Oh, she doth teach the torches to burn bright! It seems she hangs upon the cheek of night, Like a rich jewel in an Ethiope’s ear, (1.5.42-44)
Romeo and Juliet see each other for the first time.
Shakespeare uses light and dark imagery (opposing forces) in order to convey the theme of love that the two characters have to one another. Romeo describes Juliet as a white dove among the black crows showing how intense the love is between the two characters. The idea of light for Juliet demonstrates the light that she brings into Romeo's world.
Act 3 Scene 2
It best agrees with night. Come, civil night,Thou sober-suited matron, all in black,And learn me how to lose a winning matchPlayed for a pair of stainless maidenhoods.Hood my unmanned blood bating in my cheeks, (3.2.10-15)
Juliet is tormented with the conflict of the two passions as her love for her new husband finds hatred for his act of killing her beloved cousin Tybalt
The imagery of light and dark when Juliet's describes how she wants night to come adds to the theme of love as a source of light for the two main characters. It is because of how intense the love is that they both the darkness to enter in order for the light of their love to be found.