He glanced back at the wall. How like a mirror, too, her face. Impossible; for how many people did you know that refracted your own light to you? People were more often-he searched for a simile, found one in his work-torches, blazing away until they whiffed out. How rarely did other people's faces take of you and throw back to you your own expression, your own innermost trembling thought? (Bradbury 8). What two things are being compared in this example? How do you know?