Scale of colour values
THE CHESTNUT. This colour is possibly bright Bay from African blood crossed with a slight proportion of golden Dun. Both in the humans and the horses, chestnut hair goes with a certain temper described as sanguine, generous or fiery if we happen to be in a good temper, or untrustworthy and vicious if we dislike the person. Setting aside the cold sorrel, or light chestnut, which in my own mind is associated with commonplace horses and with one or two very bad women, the real chestnut, with its red-gold glory, makes most of us catch our breath with its beauty. In human hair it so appeals to artists as to be generally reserved for the most sacred portraiture. In horses, it so appeals to horsemen as to rank next bright Bay in the scale of values.
THE BROWN HORSE. This is a colder, washed-out tone of Bay.
THE BLACK HORSE. Among feral and range horses, those of the very darkest bay and brown become brown-black under the summer sunlight. True black is unknown among outdoor horses, and can only be due to special selective breeding.
THE GREY HORSE. All greys are obviously crossed between white and the various whole colours.
The primary horse colours are Dun and Bay.
The secondary colours are white, black, grey, chestnut, and brown, whole colours shared by human and horse folk.
The tertiary colours are crosses of white with Bay, Dun, black, chestnut, brown, which produce the various roans. Beyond that the human hair withdraws from competition.
The quarternary colours are crosses of white with whole roans, producing strawberry and cream roans, and roan-balds; while a peculiar mixture of white with black, bay or chestnut, gives us the piebalds and skewbalds.