To turn back what arrives — light returned, thought revisited; the mirror's verb, and the mind's.
Latin reflectere (to bend back): re- (back) + flectere (to bend); to reflect is, at the root, to bend something back toward where it came from, whether that something is light or a line of thought.
To turn back what arrives — light returned, thought revisited. The root's bending is the same act in both cases: nothing new is made, something already moving is simply sent back the way it came.