Colour Separation

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Yellow. This is the colour nearest the light. It appears on the slightest migration of light, whether by semi-transparent mediums or faint reflection from white surfaces. In prismatic experiments, it extends itself alone and widely in the light space, and while the two poles remain separated from each other, before it mixes with blue to become green it is to be seen in its utmost purity and beauty. In its highest purity, it always carries with it the nature of brightness, and has a serene, gay, softly exciting character.

Between all the colours in the world

Blue. As yellow is always accompanied with light, so it may be said that blue brings a principle of darkness with it. This colour has a peculiar and almost indescribable effect upon the eye. As a hue it is powerful, but it is on the negative side, and in the highest purity is, as it were, a stimulating negation. Its appearance, then, is a kind of contradiction between excitement and repose.

and all the colours of the world

Red. We are here to forget everything that borders on yellow or blue. We are here to imagine an absolutely pure red, like fine carmine suffered to dry on white porcelain. Whoever is acquainted with the prismatic origin of red will not think it paradoxical if we assert that this colour partly actu, partly potentia, includes all the other colours.

there is all the difference in the world.

Green. If yellow and blue, which we consider as the most fundamental and simple colours, are united as they first appear, in the first state of their action, the colour which we call green is the result. The eye experiences a distinctly grateful impression from this colour. If the two elementary colours are mixed in perfect equality so that neither predominates, the eye and the mind repose on the result of this junction as upon a simple colour. The beholder has neither the wish nor the power to imagine a state beyond it. Hence for rooms to live in constantly, the green colour is most generally selected.

Agate text: from Johann Wolfgang von Goethe, Geschichte der Farbenlehre (Theory of Colours), 1810, trans. Charles Lock Eastlake, 1840

The human body cannot create colour -- Walter Benjamin, 1926

Green Violet-ear (Colibri thalassinus), Finca Lerida, Boquete, Panama: photo by Mdf, edited by Laitche, 2008
Pigments for sale, market stall, Goa, India: photo by Dan Brady, 2005
Pillars of Sagami Temple, Hyogo, Japan: photo by 663highland, 2007
Red-eyed Tree Frog (Litoria chloris), found in eastern Australia: photo by Liquid Ghoul, edited by Muhammad, 2008