This is one of those great emails that show when you are using your Right or Left side of your brain. If you see the picture exactly as it is, you are using the left side. When you stare you will see the figure shift; and you will be using your right brain. You can switch back and forth. Stare to go to Right brain (it sort of trances you out or puts you in an altered NON THINKING state).
Begin thinking and reasoning about it and you will move back out of the altered state into Left brain thinking. very cool. You will enjoy this if you are using the right side of your brain.
Stare at this picture and you will see this man turn his face.