The painter Matthias Klotz began to investigate the subject of color beginning circa 1780 and thereby during the same general time period as Johann Wolfgang von Goethe, Philipp Otto Runge, and Gaspard Gregoire. Like the others, he was an adherent of the theory of three fundamental colors, yellow, red, and blue. With Gregoire he had in common three perceptual color attributes and an implicit cylindrical ordering system that presaged the system of Munsell. developed nearly a century later. With Runge and Gregoire he had in common a balanced color chart in which opposites were presumed to neutralize each other in a common medium gray. Klotz's so-called color canon is the most carefully executed in the early 19th century. He was unique in proposing a nine-grade, geometrically stepped gray scale that would require a logarithmic mathematical model. (C) 2008 Wiley Periodicals, Inc.