“Optical Illusions?” read Frodo.
“Yes! I first saw this book in Rivendell, and Master Elrond agreed to loan it to me. I hoped that with your talent you could copy it.”
Intrigued, Frodo opened it.
“Now, these two lines with the arrows at the end—which appears longer? Actually, they’re the same length. And these stairs--do they go up to the left—or the right? Now, this figure—what is it you see?”
“A duck,” Frodo responded, then with surprise, “No, a rabbit!” His eyes were beginning to sparkle with fascination. “How odd!”
As one who has taught people with visual problems, both having to do with problems of the eye and the various visual discrimination and interpretation centers within the brain and nervous system, I find visual perception to be a fascinating study. And optical illusions are always fun to explore. Such a book as this resides in my own library, alongside a volume that describes how studies of how people interpret such figures has revealed the heierarchical rules hardwired into our brains that allow us to properly interpret visual scenes. I can easily imagine the Elves becoming aware of optical illusions and beginning to gather examples onto volumes. Those described in this drabble are fairly common examples used to introduce people to the phenomenon.