Moses Harris (1730-c.1788) was an English entomologist and engraver who studied color theory. In his 1766 book "Natural System of Colours", Harris built upon earlier work to develop a color system based on subtractive mixing of three primary colors - red, yellow, and blue. Harris introduced the first printed color circle specifying the three primaries and showed how intermediate and compound colors could be produced by mixing the primaries. His system organized colors in a circular arrangement according to intensity based on the subtraction of wavelengths when colors are combined. Harris' work provided an alternative to Newton's additive color theory based on light.