Dr. VS Ramachandran once called the human's visual system a "bag of tricks." Although it might sound like a terribly reductive way to describe millions of years of evolution that formed such a complex way for human beings to perceive the world around them, it's hard to argue that he's wrong.
To prove that point, Ramachandran devised a super clever way of alleviating phantom limb pain for amputees using nothing but a box and mirrors. By tricking the mind into thinking their hand or foot is still there using one of these mirror boxes, patients could "itch" or "stretch" their missing limb and calm the nerve endings that don't know the limb is missing.
It was a super slick solution.