What is Cynthia's Brow?

From Shakespeare: Romeo & Juliet, act III, sc V, line 20. "'Tis but the pale reflex of Cynthia's Brow;" This is in contrast to "the morning's eye", or the sun, from line 19. Brow stands for eye-brow, which is in turn a pars-pro-toto for the whole face. Cynthia is Luna, or the moon. Cynthia's Brow therefor refers to the light which the moon casts of, the moon's glow. Cynthia = moon ; brow = eyebrow = face = what you can see of it = light. Hope that helped. ~El Pinguin Loco