The human brain is an incredibly amazing organ. It is capable of everything from complex calculations, philosophy, social interactions, and many other tasks, all while also maintaining vital functions. Without the interactions between the hemispheres in the brain, creativity would not manifest itself in humans.
However, the brain makes use of patterns and natural observances to make inferences about an object. Optical illusions take advantage of this, by tricking the brain into making an inference about the scene that is not true.
Prepare to be amazed, puzzled, and possibly even confused by these awesome examples of optical illusion photography.