In visual perception a color is almost never seen as it really is — as it physically is. This fact makes color the most relative medium in art.
In order to use color effectively it is necessary to recognize that color deceives continually. To this end, the beginning is not a study of color systems.
First, it should be learned that one and the same color evokes innumerable readings. Instead of mechanically applying or merely implying laws and rules of color harmony, distinct color effects are produced-through recognition of the interaction of color-by making, for instance, two very different colors look alike, or nearly alike.

A color has many faces, and one color can be made to appear as two different colors. Here it is almost unbelievable that the left small and the right small squares are part of the same paper strip and therefore are the same color. And no normal human eye is able to see both squares — alike.