Pepper in Philadelphia, Pennsylvania, wonders why something valuable to someone is called the apple of their eye. The expression apple of one’s eye dates back to the ninth century. It comes from misunderstanding the pupil of the eye as a sphere and not an aperture. Similarly, the French word for pupil is prunelle, or little plum. The word pupil itself comes from Latin pupilla, or little doll, because if you look deeply into someone’s eyes, you’ll see a tiny reflection of yourself. For the same reason, the expression to look babies at each other referred to the way lovers look into each others’ eyes, close enough to see themselves. This is part of a complete episode.