What literary device is used in this quote from Romeo and Juliet? "But soft, what light through yonder window breaks? "It is the east and juliet...

Romeo speaks these words soon after he has jumped over the
wall of the Capulet's garden. He wishes to see Juliet again for he is completely
infatuated with her. Romeo is standing in the garden when Juliet appears at a window
above.

He compares Juliet to a light, using a
metaphor to describe her. The fact that he sees Juliet as a
light implies that she has enlightened him (brought a new perspective), and brought
light back into his life. We must remember that he had been quite depressed about
Rosaline having rejected his advances and Juliet has brought back his joy: she has
lifted the heavy and sombre mood that he had felt. She has driven away the darkness
caused by the despair that he has been feeling because of Rosaline's cold and
indifferent attitude.

The metaphor is
extended when Romeo mentions that the position from which the light
emanates is the east, therefore indicating sunrise. His meeting with Juliet has
introduced a new dawn into his life, a new chapter. His life has been refreshed and the
dawn signifies a new birth, a new start, which is exactly what Romeo experiences at this
point.

Furthermore, the metaphor signifies
that Juliet is "the sun": she is the bringer of life, the energy that has
revitalized him. Juliet symbolizes a renewal in Romeo's life. She has brought him a new
energy. His love for her has re-energized him. There is a new purpose to his
existence and Juliet is the source of all this vitality.