What Is a Harmony Theory?

A first harmony theory can already be found with Goethe: in Goethe's theory of colors. Since then, many other relevant artists and researchers have been dealing with the esthetics of colors.
Harald Küppers describes a harmonic color composition as "the visual phenomenon which affects us esthetically". He differentiates between different characteristics, which he calls quality marks or esthetic distinguishing marks. Harald Küppers names four such esthetic distinguishing marks:

• the colorful kind
• the uncolorful kind
• the degree of colorfulness or of uncolorfulness
• the brightness

According to Küppers, these esthetic distinguishing marks are caused by quantitative relations which prevail between the subsets of which a color nuance consists.