Diderot's Encyclopedia was the ultimate representation of the Enlightenment idelas, since it had the purpouse of facilitating technical and philosophical knowledge to the common public. Due to the sheer scope of the project, which had the goal of encompasing all the knowledge of the world, it required and had many authors considered experts on their respective fields, although Diderot remained as the editor of the publication, which came out at first in France in 1751.
Colour is a essential factor for the arts as the colours add the unique and relaxation effect in a dull and boring art. Colours are used to explain the real meaning of the art or the real purpose of creating the artwork. So,I think for the uniqueness of the art colours are necessary in the arts.