They say the eyes are the window to the soul. That may be true... to a certain extant. The eyes can tell us when we're angry, happy and sad. But can the eyes tell us when we're hurt?
How often have you seen someone and known immediately something was wrong, but you couldn't put your finger on it? Probably a lot. As humans, we can be as revealing or as secretive as we wish. Simply smile and the world thinks you're happy. Put on a sad face and the world knows you're sad.
The image below is hosted on Cloudup.com. Both images are 540×922 so they can be used as Android backgrounds.