"four things were necessary in a fine horse"

The ancients believed that four things were necessary in a fine horse:
first, that he should be well formed and of goodly size, with a large chest and
muscular limbs; secondly, that he should be beautiful, with a fine head, curved
neck, and thick mane and tail; then, that he should show great spirit, which can
be judged from the trembling of his limbs. Lastly, the horse should have a
fine color. The ancients considered a chestnut horse the finest but others
prefer the colors in this order: bay, golden, ruddy, chestnut, fawn, gray,
roan, hoary, silver, white, flea-bitten, and black. Of all the colors, the
worst is the piebald.

Another selection from A Cloisters Bestiary.