"What if the water that came out of the shower was treated with a chemical that responded to a combination of things, like your heartbeat, and your body temperature, and your brain waves, so that your skin changed color according to your mood? [...] Everyone could know what everyone else felt, and we could be more careful with each other [...]. Another reason it would be a good invention is that there are so many times when you know you're feeling a lot of something but you don't know what the something is. Am I frustrated? Am I actually just panicky? And that confusion changes your mood, it becomes your mood, and you become a confused, gray person. But with the special water, you could look at your orange hands and think, I'm happy! That whole time I was actually happy!"

[J. S. Foer, Extremely Loud and Incredibly Close]