Tertiary color if they exist at all, though indigo and scarlet are standard for blue–violet and red–vermilion. In another sense, a tertiary color is obtained by mixing secondary-colored pigments. These three colors are russet (orange–purple), slate (purple–green), and citron (green–orange), with the corresponding three quaternary colors plum (russet–slate), sage (slate–citron), buff (citron–russet) (with olive sometimes used for either slate or citron). Beyond that are shades of grey (blue grey and brown greys), which approach but never quite reach black. The RYB color terminology outlined above and in the color samples shown below is ultimately derived from the 1835 book "Chromatography", an analysis
On Vision and Colors darken into black. If the remainder is only partially inactive, then the color loses its energy by mixing with gray. If the activity of the retina is divided without a remainder, or if the remainder is active, then a color and its spectrum (afterimage) are bright or pale. When such a color and its spectrum are united, then the eye sees pure light or white. For example, the mixture of bright or pale red and green on the same retinal spot results in the impression there of light or white. White cannot be produced by mixing colored pigments. With colors