can never have profound meaning […]
may be paralleled in human nature with madness,
not with melancholy or hypochondriacal mania,
but rather with violent raving lunacy.
Two great divisions of colour occur to the mind at the outset:
Into warm and cold, and into light and dark.
To each colour there are therefore four shades of appeal -
Warm and light or warm and dark,
or cold and light or cold and dark.