Objects in the natural world are seldom fully seen. Often only partially visible, their contours provide clues for constructing the unseen portions of the object. Most of what we take for normal is a visual illusion because it ignores “negative space,” the area where the unseen portion of the image exists.
For example, the Chinese have a written phrase that translates: lower water, expose rocks.
The student is taught its deeper meaning orally, while the uninitiated are left to discover through trial and error.