But, soft! what light through yonder window breaks...cast it off. (2.2.3-10)
But, soft! what light through yonder window breaks?
It is the east, and Juliet is the sun.
Arise, fair sun, and kill the envious moon,
Who is already sick and pale with grief,
That thou her maid art far more fair than she:
Be not her maid, since she is envious;
Her vestal livery is but sick and green
And none but fools do wear it; cast it off. (2.2.3-10)
In this passage Romeo uses an intricate conceit to express a simple desire: to take Juliet's virginity. Romeo begins by saying that the envious moon, i.e., Diana, goddess of the moon and patron of virgins, is jealous of her servant's (Juliet's) radiance. He then begs Juliet to be Diana’s maid no longer; for the virginal uniform (vestal livery) she wears as a follower of Diana is sickly green in color, and not to remove it (i.e., to remain a virgin) would be foolish.
The phrase sick and green was hotly debated among early scholars, because of a discrepancy among the printed versions of the play. In the first quarto of Romeo and Juliet (1597), the line reads pale and green, which invites a new explanation of the lines, Her vestal livery is but sick and green/And none but fools do wear it. Some editors charge the compositors of the subsequent quartos and the First Folio (where it appears as sick and green) with carelessness, convinced that Shakespeare intended pale and green not to mean the green sickness of anaemia (as is described three lines above), but to mean the colors of the uniform worn by Henry VIII's court jester – white and green. Thus, her vestal livery is the garb of a fool.