This cube is called a “Necker Cube”, and, according to my recollection of my first year Psychology lectures, is a classic demonstration of the way the brain perceives things.
When you first look at this cube, you are likely to see it only one way. Either you will see the bottom left face to the front. Or you will see the top right face to the front. But keep staring at it, and suddenly it will switch on you: as if moving in space. As you keep looking – it will switch back to its original configuration.
The thing I like about the Necker Cube is, once you have seen the switch happen, it will never look stable again. The cube will constantly switch back and forth before your eyes. It’s as if your brain has become more supple.