Sight is arguably one of the most important senses and the eye the most delicate of organs. Vision occurs when light enters the eye through the pupil and is then redirected through the lens. The human eye comprises millions of specialist cells known as rods and cones, and it is thought that there are three types of cones, each sensitive to the wavelength of a different primary colour - red, green or blue. Other colours are seen as combinations of these primary colours that when mixed together reflect vibrant, glowing and luminous colour that, well, colours our lives.

The purest artists’ colours come from pigments. A list of these from a London colourman reads like an alchemist’s notebook:

madder root pieces (pinks),
malachite (green),
azurite (blue),
lapis lazuli (blue) ,
gamboge pieces and powder (orange),
verdigris (green),
smalt (blue),
litharge (pale yellow),
vermillion (red,
realgar (orange-brown).

Metals listed in the Periodic Table: cadmium, cobalt, titanium, lead, alongside chemical compounds arsenic trisulphide (bright yellow), arsenic disulphide (yellow-orange), mercuric sulphide (bright opaque red), copper silicates (blue), hydrated copper acetate (green) create a chemistry of colour. Then there is the geography of colour: Naples yellow, Antwerp blue, Sienna burnt and raw, Indian red and Mars, the red planet, names yellow, black and violet. The apparent contradiction of colour: ivory black, made originally from charred elephant tusks as they gave the densest blackest black.

In the history of colour the earth colours were easily won powdered as they were from earth and stone, distilled from flower petals and plants, or crushed from roots and barks. Benign and beautiful; other colours were deadly. Lead dissolved in vinegar produced a white residue that when mixed with a medium was used as a ground for paintings. Lead White is poisonous; the chief cause of painters’ colic. Arsenic green (known also as Paris, Parrot and Vienna green) was the colour of Napoleon’s wallpaper in his prison which rotted in the damp of St Helena and poisoned the French emperor as arsenic gas was released from the leafy pattern.

The first ‘artificial’ pigment Prussian Blue was made around 1704 by Diesbach, a German colourman, from ground bones and blood. In 1856 the British chemist William Perkins discovered the first aniline dye, mauveine, now known as mauve. In 1963 Pantone® developed their colour matching system for printing inks: based around cyan, magenta, yellow and black with 15 base pigments (including black and white) over a thousand different hues were classified and numbered. The Scottish Parliament voted Pantone® 300 as the blue of the Saltire, the national flag. It is an official colour, as red is for stop and green is for go.

We not only speak of colour but with colour: ‘Those blue remember hills’(1) ; ‘a rose-red city half as old as time’(2) ; we have red letter days (3); we grow pinks (dianthus) in our flower beds, and write in purple prose (4). We eat up our greens (cabbage, spinach chard and the like) and the citrus fruits give name to colour - orange, tangerine and lime. Colour truly is the stuff of life.

(1) A E Housman, A Shropshire Lad (1896)
(2) John William Burgon, Petra (1845)
(3)The term refers to the use of red inked capital letters in medieval ecclesiastical manuscripts to mark feasts and holy days; known also as Rubrics
(4)A literary criticism term referring to extravagant, ornate and flowery language; text that is overly stylized so that interferes with the narrative flow.