Again, where the two interior colour-cones merge, there an additional colour appears. Like green, it is of a neutral character, but at the same time its quality is opposite to that of green. In Newtonian optics, which assumes colour to be derived from light only, this colour has naturally no existence. Yet in an optics which has learnt to reckon with both darkness and light as generators of colour, the complete spectrum phenomenon includes this colour equally with green. For lack of an existing proper name for it, Goethe termed it ‘pure red’ (since it was free from both the blue tinge of the mauve, and the yellow tinge of the red end of the ordinary spectrum), or ‘peach-blossom’ (pfirsichblüt), or ‘purple’ (as being nearest to the dye-stuff so called by the ancients after the mollusc from which it was obtained).¹⁰