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SUTRA 23.
colours of a canvas painter are red, green, and bluishviolet from which any desired colour can be produced by mixing these three powders in different proportions, whereas in tri-colour printing on paper red, yellow and blue are the colours required. Even in the case of colours of solar spectrum it can be demonstrated that if red light is cut off from the spectrum by an opaque screen and the remaining six colours then re-combined by a prism, the resulting light would be green, showing thereby that what appears to be green, is only white light minus red. Then there is also a distinction between a mixture of spectral colours and that of pigment colours. Blue and yellow light, when mixed, produce white light, whereas blue and yellow pigments, mixed together would produce a green paint. This discussion clearly shows that the above sutra, describing the fundamental properties of matter, refers neither to spectral colours nor to pigmentary.
It may be mentioned in addition that the definition of 'colour' adopted by the Optical Society of America (see Report of the Colorimetry Committee, 1922) is as follows:
"Colour is the general term for all sensations arising from activity of the retina and its attached nervous mechanisms. It may be exemplified by the enumeration of characteristic instances, such as red, yellow, blue, black and white......"
It shows perfect agreement with the Jaina view.
125
Heart leaps with joy at the sight of this exact coincidence in the classification of these natural colours. The study of Nature by our forefathers appears to be no less critical than the modern one.
282
With regard to the infinite gradations of these five colours (vide page 119 ante), one word may be said about the fundamental nature of colour. Just as a difference of wave-length in sound produces difference of note, similarly difference of wavelength in visible light produces difference of colour. "It is usual to regard light as a wave-motion, each wavelength corresponding to a definite colour" (Max Born). The shortest light-waves that the human eye can see are the waves of violet light. As
282. Sound and light energies travel in space in the form of waves. The most common form of wave is one which is produced over the surface of a pond by dropping a piece of stone. The distance from one wave-crest to another is called the wave-length.
