Thomas Young, while advancing his theory of light as undulations in a luminiferous elastic ether, brought Newton's observations on the perception of color back into public awareness with the observation that ``The sensation of different Colours depends on the different frequency of Vibrations, excited by Light in the Retina'' [Young 1802]. Young further suggested that the retina might be sensitive to only three principal colors and that all appearance of color might be attributable to varying degrees of excitation of these three receptors.
Now, as it is almost impossible to conceive each sensitive point of the retina to contain an infinite number of particles, each capable of vibrating in perfect unison with every possible undulation, it becomes necessary to suppose the number limited, for instance, to the three principal colours, red, yellow, and blue, of which the undulations are related in magnitude nearly as the numbers 8, 7, and 6; and that each of the particles is capable of being put in motion less or more forcibley by undulations differing less or more from a perfect unison; for instance the undulations of green light being nearly in the ratio of , will affect equally the particles in unison with yellow and blue, and produce the same effect as a light composed of these two species: and each sensitive filament of the nerve may consist of three portions, one for each principal colour. [Young 1802, page 21,]
While Young made an interesting and prescient guess about the nature of color perception, his choice of the three subtractive primary colors would continue to confuse color researchers for another fifty years.