Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
When a white horse is not a horse acknowledge the age of an old man? And what is it which is called righteousness? The fact of a man's being old? Or the fact of our giving honour to his age?' Other early "A white horse is not a horse" references are found in the "Hanfeizi" (32), "Mozi" (11B), and "Zhanguoce" (4). When a white horse is not a horse When A White Horse Is Not A Horse (), also known as the White Horse Dialogue (), is a famous paradox in Chinese philosophy. Gongsun Long wrote this circa 300 BC dialectic analysis of the question 'Is "white horse